The human body and its health biology. Human

5.1. Fabrics. The structure and vital functions of organs and organ systems: digestion, respiration, blood circulation, lymphatic system

5.1.1. Human anatomy and physiology. Fabrics

Basic categories and terminology tested in the examination process (USE): Anatomy, types of tissues (epithelial, muscle, connective, nervous), location of tissues, organ, organism, characteristics of tissues, functions of tissues.

Anatomy is a private biological science that studies the structure of the human body, its parts, organs and organ systems. Anatomy is studied in parallel with physiology, the science of body functions. The science that studies the conditions of normal life of the human body is called hygiene.
Tissue is an evolutionarily developed system of cells and intercellular substance that has a common structure, development and performs certain functions.
Tissues that form the human body.

Organs are formed from tissues, with one of the organ tissues being dominant. Organs that are similar in their structure, functions and development are combined into organ systems: musculoskeletal, digestive, circulatory, lymphatic, respiratory, excretory, nervous, sensory system, endocrine, reproductive. Organ systems are anatomically and functionally connected to the body. The body is capable of self-regulation. This ensures its resistance to environmental influences. All body functions are controlled by the neurohumoral pathway, i.e. combining nervous and humoral regulation.

Unified State Exam Part A

A1. Epithelial tissue forms
1) intestinal mucosa
2) articular capsule
3) subcutaneous fat tissue
4) blood and lymph
A2. Connective tissue can be distinguished from epithelial tissue by
1) the number of nuclei in cells
2) the amount of intercellular substance
3) shape and size of cells
4) transverse striations
A3. Connective tissue includes
1) upper, exfoliating skin cells
2) cells of the gray matter of the brain
3) cells that form the cornea of ​​the eye
4) blood cells, cartilage
A4. Mononuclear, spindle-shaped cells with contractile fibers belong to
1) striated muscles
2) smooth muscles
3) bone connective tissue
4) fibrous connective tissue
A5. The main properties of nervous tissue are
1) contractility and conductivity
2) excitability and contractility
3) excitability and conductivity
4) contractility and irritability
A6. Smooth muscle tissue is formed
1) ventricles of the heart
2) stomach walls
3) facial muscles
4) muscles of the eyeball
A7. The biceps brachii muscle consists primarily of
smooth muscle
cartilaginous connective tissue
striated muscles
fibrous connective tissue
A8. Slowly and involuntarily contract, little fatigue
1) stomach muscles 3) leg muscles
2) arm muscles 4) heart muscle
A9. Receptors are
1) nerve endings 3) dendrites
2) axons 4) neurons
A10. The largest amount of ATP is found in cells
1) skin 3) intervertebral discs
2) heart muscle 4) femur

Unified State Exam Part B

IN 1. Select signs of connective tissue
1) tissue is excitable
2) well developed intercellular substance
3) some tissue cells are capable of phagocytosis
4) contract in response to irritation
5) the tissue can be formed by cartilage, fibers
6) conducts nerve impulses
AT 2. Match the type of fabric with its characteristics

5.1.2. Structure and functions of the digestive system

Basic categories and terminology tested in the examination process (USE): Absorption, organs, digestive system, regulation of digestion, structure of the digestive system, organ system, enzymes.

The digestive system is a system of organs in which the mechanical and chemical processing of food, the absorption of processed substances and the excretion of undigested and undigested components of food are carried out. It is divided into the digestive tract and digestive glands. The digestive tract consists of the following sections: oral cavity, pharynx, esophagus, stomach, small intestine, large intestine. The digestive glands include the liver and the part of the pancreas that secretes digestive enzymes. The oral cavity contains teeth, a tongue, and the outlet openings of the ducts of three pairs of large and several small salivary glands.
Saliva is the secretion of the salivary glands. The secretion of saliva occurs reflexively and is coordinated by the centers of the medulla oblongata. Saliva contains enzymes that break down carbohydrates.
The pharynx is divided into the nasopharynx, oropharynx and laryngeal part. The pharynx communicates with the oral cavity and the larynx. When swallowing, which is a reflex act, the epiglottis closes the entrance to the larynx and the food bolus enters the pharynx and is then pushed into the esophagus.
The esophagus, the upper third of which is formed by striated muscle tissue, passes through the opening of the diaphragm into the abdominal cavity and passes into the stomach. Food moves through the esophagus thanks to its peristalsis - contractions of the muscles of the esophagus wall.
The stomach is the extended part of the digestive tube in which food is stored and digested. Proteins and fats begin to be digested in the stomach. The gastric mucosa contains several types of cells.
The glandular cells of the stomach secrete 2.0 - 2.5 liters of gastric juice per day. Its composition depends on the nature of the food. Gastric juice is acidic. The hydrochloric acid included in its composition activates the enzyme of gastric juice - pepsin, causes swelling and denaturation of proteins and promotes their subsequent breakdown into amino acids. Mucus protects the lining of the stomach from mechanical and chemical irritations. In addition to pepsin, gastric juice also contains other enzymes that ensure the breakdown of fats and curdling of milk.
I.P. studied the mechanisms of digestion. Pavlov. He developed a method of placing a fistula (hole) in the dog's stomach in combination with cutting the esophagus. The food did not enter the stomach, but nevertheless caused a reflex secretion of gastric juice, which occurs under the influence of taste, smell, and type of food. Receptors in the mouth and stomach are stimulated by food chemicals. The impulses enter the digestive center in the medulla oblongata, and then from it to the glands of the stomach, causing the secretion of gastric juice.
Regulation of juice secretion also occurs through humoral means. The bolus of food from the stomach passes into the duodenum. The main digestive glands are the liver and pancreas.
Liver - located on the right side of the abdominal cavity, under the diaphragm. Consists of lobules that are formed by liver cells. The liver is abundantly supplied with blood and bile capillaries. Bile flows from the liver through the bile duct into the duodenum. The pancreatic duct opens there. Bile is constantly secreted and has an alkaline reaction. Bile consists of water, bile acids and bile pigments. There are no digestive enzymes in bile, but it activates the action of digestive enzymes, emulsifies fats, creates an alkaline environment in the small intestine, and enhances the secretion of pancreatic juices. The liver also performs a barrier function, neutralizing toxins, ammonia and other products formed during the metabolic process. The pancreas is located on the posterior abdominal wall, slightly behind the stomach, in the loop of the duodenum. This is a mixed secretion gland that secretes pancreatic juice in its exocrine part, and the hormones glucagon and insulin in its endocrine part.
Pancreatic juice (2.0 - 2.5 liters per day) has an alkaline reaction.
The small intestine consists of the duodenum, jejunum and ileum. Its total length is approximately 5-6 m. The mucous membrane of the small intestine secretes intestinal juice, the enzymes of which ensure the final breakdown of nutrients. Digestion occurs both in the intestinal cavity (cavitary) and on cell membranes (parietal), which form a huge number of villi lining the small intestine. Digestive enzymes act on the membranes of the villi. In the center of each villi there are lymphatic capillaries and blood capillaries. The products of fat processing enter the lymph, and amino acids and simple carbohydrates enter the blood. Peristalsis of the small intestine ensures the movement of food to the large intestine.
The large intestine is formed by the cecum, colon and rectum. Its length is 1.5-2 m. The cecum has an appendix - the appendix. The glands of the colon produce juice that does not contain enzymes, but contains mucus necessary for the formation of feces. Bacteria of the large intestine perform a number of functions - fermentation of fiber, synthesis of vitamins K and B, rotting of proteins. Water and fiber breakdown products are absorbed in the large intestine. Protein breakdown products are neutralized in the liver. Food debris accumulates in the rectum and is removed through the anus.
Regulation of digestion. The center of digestion is located in the medulla oblongata. The center of defecation is located in the lumbosacral spinal cord. The sympathetic part of the nervous system weakens, and the parasympathetic part increases peristalsis and juice secretion. Humoral regulation is carried out both by the hormones of the gastrointestinal tract and by hormones of the endocrine system (adrenaline). You need to eat fresh, good quality food. Adequate nutrition ensures that energy costs correspond to their replenishment. The average daily requirement for proteins is approximately 100-150 g, for carbohydrates - 400-500 g and for fats - about 80 g.

Examples of practical tasks of the Unified State Exam on the topic: ““
Unified State Exam Part A

A1. Begins to be partially digested in the mouth
1) chicken egg white 3) white bread
2) butter 4) beef
A2. Proteins begin to be digested with the help of enzymes
1) saliva 3) intestinal juice
2) gastric juice 4) bile
A3. Process of final digestion and absorption
nutrients occurs in
1) stomach 3) colon
2) oral cavity 4) small intestine
A4. Metabolic products are neutralized in
1) large intestine 3) pancreas
2) small intestine 4) liver
A5. The process of moving food through the digestive tract is ensured
1) mucous membranes of the digestive tract
2) secretions of the digestive glands
3) peristalsis of the esophagus, stomach, intestines
4) activity of digestive juices
A6. Destroying colon bacteria can cause digestion problems
1) proteins 3) glucose
2) fats 4) fiber
A7. With low acidity of gastric juice, digestion may be impaired
1) proteins 3) carbohydrates
2) fats 4) nucleic acids
A8. Absorbed into the blood in the small intestine
1) lipids 3) amino acids
2) proteins 4) glycogen
A9. The digestive center is located in
1) spinal cord 3) diencephalon
2) midbrain 4) medulla oblongata

Unified State Exam Part B

IN 1. Select the processes occurring in the small intestine
1) the beginning of the breakdown of carbohydrates
2) the beginning of the digestion of proteins and lipids
3) final breakdown of proteins
4) absorption of amino acids and monosaccharides
5) breakdown of fiber
6) parietal digestion
AT 2. Select the digestive processes that occur in the stomach
1) breakdown of proteins by pepsin and other enzymes
2) neutralization of protein breakdown products
3) absorption of lipids into lymph
4) release of hydrochloric acid
5) treatment of the food bolus with bile
6) secretion of mucus that protects the stomach
VZ. Establish the correct sequence of passage of a bolus of food through the digestive tract
A) esophagus
B) oral cavity
B) stomach
D) pharynx
D) small intestine
E) duodenum
G) large intestine
3) rectum

Unified State Examination Part C

C1. How does hunger differ from appetite?
C2. What happens to food in the digestive tract?

Lecture, abstract. Man and his health - concept and types. Classification, essence and features.

Book table of contents open close

Biology - the science of life
Cell as a biological system
The structure of pro- and eukaryotic cells. The relationship between the structure and functions of the parts and organelles of a cell is the basis of its integrity
Metabolism, enzymes, energy metabolism
Biosynthesis of protein and nucleic acids.
A cell is the genetic unit of a living thing.
Organism as a biological system
Ontogenesis and its inherent patterns.
Genetics, its tasks. Heredity and variability are properties of organisms. Basic genetic concepts
Patterns of heredity, their cytological basis.
Variability of characteristics in organisms - modification, mutation, combination
Selection, its objectives and practical significance
Diversity of organisms, their structure and life activity
Kingdom of Bacteria.
Kingdom of Mushrooms.
Plant Kingdom
Plant diversity
Animal Kingdom.
Chordata animals, their classification, structural features and vital functions, role in nature and human life
Superclass Pisces
Class Amphibians.
Class Reptiles.
Bird class
Class Mammals
Man and his health
Structure and functions of the respiratory system
Structure and functions of the excretory system
The structure and vital functions of organs and organ systems - musculoskeletal, integumentary, blood circulation, lymph circulation.
Skin, its structure and functions
Internal environment of the human body. Blood groups.
Metabolism in the human body

Biological sciences such as anatomy, physiology, hygiene, valeology, etc. study the human body and its health. Anatomy- the science of the structure and form of the body, its organs and their systems. Physiology- the science of the functions of the whole organism, its organs and their systems. Hygiene- the science of the influence of living and working conditions on human health. Valeology- the science of preserving and promoting health. N.I. Pirogov, I.M. Sechenov, I.P. Pavlov, S.P. Botkin, V.M. Bekhterev and others contributed to the development of these sciences. These and other biological sciences are the theoretical basis of medicine. Health is the wealth of a person and society.

Fabrics

A person is a complex self-regulating and self-renewing system of cells and non-cellular structures, which in the process of development form tissues, organs and organ systems, united by cellular, humoral, and nervous regulatory mechanisms into an integral organism.
Textile- a set of cells similar in structure, function and origin, as well as the intercellular substance associated with them. In humans, there are 4 main types (groups) of tissue: epithelial, connective, muscle and nervous.
Epithelial tissue cover the surface of the body, line the inside of hollow organs and the walls of body cavities, and form glands. Epithelial tissues contain little intercellular substance and do not have blood vessels. There are single-layered, stratified and glandular epithelia.
Single layer epithelium depending on the shape of the cells and other structural features, it can be flat (serous membranes), cubic (renal tubules), cylindrical (intestinal epithelium), multirow ciliated, having cilia (airways).
Stratified epithelium It can be keratinizing (epidermis of the skin), non-keratinizing (cornea of ​​the eye) and transitional (bladder).
Glandular epithelium forms glands (pancreas, liver, salivary and sweat glands, etc.).
Epithelial tissues perform the following functions: protective, secretory, excretory, metabolism between the body and the external environment.
Connective tissues have a well-developed intercellular substance. There are several types of connective tissues.
Loose fibrous connective tissue It is represented by fibers arranged loosely and lying in different directions. Accompanies blood vessels, nerves, forms the stroma of organs, forming their soft skeleton.
Dense fibrous connective tissue forms a mesh layer of skin, forms muscle tendons, ligaments, membranes, fascia, vocal cords, part of the membranes of organs, elastic membranes of blood vessels.
Adipose tissue located in the subcutaneous fat layer, omentum, intestinal mesentery, and in the fatty capsule of the kidneys.
Cartilage tissue consists of cells and a dense intercellular substance consisting of amorphous substance and fibers.
Bone includes cells and intercellular substance in the form of plates impregnated with mineral salts. Together with cartilage tissue, it gives strength to the spine and other parts of the skeleton.
Reticular tissue forms hematopoietic organs (red bone marrow, lymph nodes, spleen).
Blood And lymph have an intercellular substance of liquid consistency, where cellular elements are suspended.
Connective tissues perform the following functions: trophic (associated with the participation of cells in metabolism), protective (phagocytosis, production of immune bodies), mechanical (form the stroma of organs, fascia, ligaments, skeleton), plastic (participate in regeneration processes, wound healing), homeostatic (ensure the maintenance of a constant internal environment of the body).
Muscle tissue have the properties of contractility and excitability and provide motor processes in the body. Muscle tissue cells in the cytoplasm have microfilaments capable of contraction. A person has 3 types of muscle tissue: striated (skeletal), smooth and cardiac. Each type of tissue has its own type of muscle fiber.
Skeletal (striated) muscle tissue forms skeletal muscles, muscles of the tongue, soft palate, pharynx, upper part of the esophagus, larynx, etc. It is represented by large multinucleated cells up to 10–12 cm long, called muscle fibers. The cytoplasm of these cells contains a contractile apparatus in the form myofibrils. Myofibrils contain many fibers - myofilaments. Thinner myofilaments are made of actin protein, thicker ones are made of protein myosin. When a muscle fiber contracts, actin filaments slide between myosin filaments, resulting in shortening of the fiber. This process requires Ca2+ ions and ATP energy.
Smooth muscle tissue is part of the walls of internal organs and blood vessels. Its cells are small, mononuclear, and spindle-shaped. The cytoplasm contains myofibrils capable of contraction.
Cardiac muscle tissue is part of the heart. The heart muscle is formed by striated muscle tissue of a special structure. In it, neighboring muscle fibers are interconnected by cytoplasmic bridges. Intercellular connections do not interfere with the conduction of excitation, due to which the heart muscle is able to contract quickly. In nerve cells and skeletal muscles, each cell fires separately.
There are functional differences between smooth and striated muscle tissue. Smooth muscles contract slowly, involuntarily, and are little fatigued. Striated muscles contract quickly, voluntarily, and quickly tire.
Nervous tissue formed by nerve cells (neurons) and neuroglia. Neurons consist of body And processes: one long unbranched axon(conducts nerve impulses from the cell body) and short branching dendrites(conduct a nerve impulse to the cell body). The axons are covered with a light myelin sheath and form white matter. Neuron cell bodies and dendrites form Gray matter.

Neurons are divided into sensory, motor and intercalary. Sensitive neurons transmit excitation from the sensory organs to the spinal cord and brain. Motor (executive) transmit excitation from the brain and spinal cord to the muscles and internal organs. The connection between them is carried out interneurons located in the spinal cord and brain.
Nerve processes form nerve fibers. Bundles of nerve fibers form nerves. Nerves are divided into sensory, motor and mixed. Dendrites of sensory neurons form sensory nerves, and the axons of motor neurons - motor nerves. However, most nerves are mixed.

Organs and organ systems

Organ- a part of an organism that has a certain shape, structure and location and performs one or more functions. Each organ is formed by several tissues, but one of them always predominates and determines its main function. Each organ always contains nervous and connective tissue (nerves, blood and lymphatic vessels). Internal organs are organs located in body cavities.
Organ system- a set of organs that jointly perform certain functions. In the human body, the following organ systems are distinguished: musculoskeletal, digestive, respiratory, excretory, circulatory, lymphatic, nervous, sensory organs, endocrine glands, and reproductive systems. Functional system - organs and organ systems temporarily combined to achieve some result. For example, when running, the musculoskeletal, respiratory, circulatory and other systems are involved.

Skeleton

The musculoskeletal system is made up of bones, muscles, tendons and ligaments. Its main functions are support and protection. Bones perform the function of support and protection, and also serve as a place for muscle attachment. Muscles change the position of the body in space, and also perform a protective function. Ligaments connect bones together tendons connect bones and muscles. The skeleton and its connections are the passive part of the movement apparatus, and the skeletal muscles attached to the bones are the active part.

Bone structure

The bones of the skeleton are formed mainly bone tissue(a type of connective tissue). It consists of 2/3 of hard and dense intercellular substance. Bone cells (osteocytes) communicate with each other through “tubules” filled with intercellular fluid. Bone tissue is supplied with nerves and blood vessels. Bone tissue contains: organic substances (collagen, ossein, etc.) that give elasticity and firmness, and inorganic(calcium, phosphorus, magnesium, sodium, etc.), which impart hardness. Their combination provides strength. With age, the amount of inorganic substances in the bones increases and they become more fragile.

Let's look at the structure of a long tubular bone. It consists of a middle part - the body of the bone (diaphysis) and two extended ends - heads (epiphyses). The diaphysis is formed compact bone substance and has a bone marrow canal filled yellow bone marrow; covered on top periosteum. The epiphyses are formed by spongy substance and filled red bone marrow(are a hematopoietic organ); covered on top with articular cartilage.
Growth in thickness is carried out by the division of cells of the periosteum, in length - by division of the cells of the cartilage tissue covering the ends of the bones. Bone growth is regulated by growth hormone secreted by the pituitary gland. In an adult body, only bone substance is replaced.
The skeleton of the human embryo consists only of cartilage, which is gradually replaced by bone tissue. The process of skeletal ossification and bone growth ends by the age of 22–25.
There are four groups of bones: tubular(long, short), spongy(long, short, sesamoid), flat And mixed.
Tubular bones built of compact and spongy substance and have a medullary canal. Long tubular bones: bones of the shoulder, forearm, thigh and lower leg. Short tubular bones: bones of the metacarpus, metatarsus, phalanges of the fingers.
Spongy bones built primarily of spongy substance covered with a thin layer of compact. Long spongy bones: ribs and sternum. Short cancellous bones: vertebrae, carpal and tarsal bones. Sesamoid spongy bones located in muscle tendons, near some joints (patella).
Flat Bones consist of two plates of compact substance, between which there is spongy substance (part of the bones of the skull, scapula, pelvic bones).
Mixed dice are formed from several parts with different shapes and development (bones of the base of the skull).

Bone connections

Bone joints provide either mobility or stability to parts of the skeleton. Depending on this connection of bones with each other there may be motionless(coccyx vertebrae, skull bones), semi-movable (half-joints)(vertebrae in the spine) and movable (joints).

A joint consists of one bone with a glenoid cavity and another bone with a head (the articular surfaces of the bones are covered with cartilage), strong ligaments (provide strength to the connection of the bones), an articular capsule (in which there is negative pressure, which increases the convergence of the articular surfaces) and joint fluid (to reduce friction). Half-joints have cartilage pads between the bones.

Skeletal departments

The human skeleton consists of the skeleton of the head (cerebral and facial sections), the skeleton of the torso (vertebral column and rib cage), the skeleton of the upper and lower extremities (the skeleton of the belts and the skeleton of the free upper and lower extremities). There are about 220 bones in total.

Head skeleton (skull) includes 23 bones and consists of the brain and facial sections.

The main bones of the skull are as follows. Part brain section includes paired bones - parietal and temporal, unpaired - frontal, occipital. Part facial section includes the fixed maxillary, movable mandibular, nasal and zygomatic bones. The jawbones contain teeth. All bones of the skull, except the mandibular, are characterized by a continuous connection with each other (interosseous sutures).
Skeleton of the torso consists of the spine and rib cage. Spine consists of 33–34 vertebrae, each of which has body, arc and several processes. Between the vertebrae there are layers of cartilage tissue that provide flexibility. Spine sections: cervical (7 vertebrae), thoracic (12 vertebrae), lumbar (5 vertebrae), sacral (5 vertebrae), coccygeal (4–5 vertebrae). The curves of the spine (cervical, thoracic, lumbar and sacral) give it elasticity. Two of them (cervical and lumbar), directed with their convexity forward, - lordosis, and two (thoracic and sacral), directed with convexity backwards, - kyphosis. Children are born with an almost straight spine. The development of the cervical curve is associated with the child’s ability to hold his head up, the thoracic curve with sitting, and the lumbar and sacral curve with standing and walking. Thanks to the bends, the shaking of the head and torso when walking, running, jumping is weakened, and balance is maintained. Rib cage formed by 12 pairs of ribs and the sternum. Of the ribs, 7 pairs are true ribs (connected to the sternum), 3 pairs are false (attached to the cartilage of other ribs), 2 pairs are floating (end freely in soft tissues).
Skeleton of the upper limbs comprises shoulder girdle skeleton(shoulder blades and collarbones) and skeleton free upper limb: shoulder(brachial bone), forearm(ulna and radius bones) and brush(bones of the wrist, metacarpus, phalanges).
Skeleton of the lower limbs comprises lower limb belts (two pelvic bones and the sacrum) and skeleton of the free lower limb: hip(femur), shin(tibia and fibula) and foot(tarsal bones, metatarsals, phalanges).
Skeletal features associated with upright walking and work activity. The spine has curves that spring back. The chest is expanded to the sides. The girdle of the lower extremities is wide and bowl-shaped; it serves as a support for the internal organs of the abdominal cavity. The bones of the lower extremities are thicker and stronger than the bones of the arms, as they bear the entire weight of the body. The foot is arched and springy. The hand is an organ of labor: the bones of the fingers are movable, the thumb is opposite the rest. The cerebral part of the skull predominates over the facial part.

Muscles

Muscle structure

Skeletal muscles perform the following functions: moving the body in space, moving parts of the body relative to each other, maintaining posture, formation of the chest and abdominal cavities, respiratory movements, chewing and swallowing, facial expressions, articulation of sounds, etc.
Skeletal muscles are formed striated muscle fibers, which carry out its reduction. Muscle fibers are collected in bundles, between which there are layers of connective tissue that perform a supporting function. They contain blood vessels and nerves. Individual muscles and muscle groups are surrounded by dense and durable sheaths of connective tissue - fascia. Muscles are attached to bones by tendons. Depending on the number of initial parts (heads) and middle parts (abdomens), muscles can be bi-, tri- and quadriceps, digastric, etc. Some muscles are not associated with bones (muscles of the face, eyes, mouth). According to their shape, muscles are divided into long, short and wide.
Skeletal muscle makes up about 40% of the human body weight and contains about 400 skeletal muscles. The muscles of the head, neck, torso, upper and lower extremities are distinguished by location.

Muscle work

According to their functions, muscles are divided into flexors and extensors, adductors and abductors, synergists and antagonists, etc.
Skeletal muscles are attached to both sides of the joint and, when contracted, produce movement in it. Flexors(flexors) are usually located in front, and extensors(extensors) - behind the joint (except for the knee and ankle joints).
Abductors muscles (abductors) are located outside the joint, leading(adductors) - medially from the joint. Rotation is produced by muscles located obliquely or transversely with respect to the vertical axis (pronators - rotating inward, instep supinators - outward).
Synergists- muscles that move the joint in one direction (brachialis and biceps brachii), antagonists- muscles that perform opposite functions (biceps and triceps brachii).
The work of different muscle groups occurs in concert. When the flexor is contracted, the extensor is relaxed, and vice versa. This occurs when alternating processes of excitation and inhibition in the spinal cord. On the other hand, the flexors and extensors can be simultaneously relaxed or contracted. The nervous system plays the main role in coordinating movements.
With intense muscle activity, fatigue may occur. Fatigue- a temporary decrease in the performance of a cell, organ or whole organism that occurs as a result of work and disappears after rest. Fatigue depends on the rhythm of contractions and the load. Static work muscle contraction requires simultaneous contraction of all muscle groups and therefore cannot be prolonged. At dynamic work Different muscle groups contract alternately, which makes it possible to perform work for a long time.
Under experimental conditions, muscle fatigue is associated with the accumulation of metabolic products in it (phosphoric, lactic acids), which affect the excitability of the cell membrane, as well as with the depletion of energy reserves. With prolonged muscle work, glycogen reserves in it decrease and, accordingly, the processes of ATP synthesis necessary for contraction are disrupted. It has been established that under natural conditions the process of fatigue affects, first of all, the central nervous system, then the neuromuscular synapse and, lastly, the muscle.
Training muscles increases their volume, strength and endurance. When training muscles, muscle fibers thicken, the amount of glycogen in them increases, the oxygen utilization rate increases, and recovery processes accelerate.

Selection

During the metabolic process, breakdown products are formed. Some of them are used by the body to form new cells, others are removed from it. Selection is the process of removing metabolic end products that can no longer be used by the body.
The function of the excretory system is the release of metabolic end products that are unnecessary for the body. Excretion is necessary to maintain a constant internal environment of the body.
Organs of the excretory system: kidneys, lungs, intestines, sweat glands. Kidneys are the main excretory organs. They remove water, urea, mineral salts, some organic substances, and many harmful and toxic substances from the body. Lungs release carbon dioxide, water and some volatile substances. Intestines removes salts of heavy metals, products of the transformation of bile pigments. Sweat glands excrete water, uric acid, urea, ammonia, salts, etc. in the sweat.
Thus, carbon dioxide is removed from the body through the lungs; water - through the kidneys, lungs and skin; urea - through the kidneys; mineral salts and some organic substances - through the kidneys and skin.
Urinary system. Organs of the urinary system: kidneys, ureters, bladder, urethra. Function is the release of the final products of metabolism: water, mineral salts, urea, as well as various foreign and toxic substances (for example, drugs), maintaining the constancy of the ionic composition, osmotic pressure, pH of the blood and tissue fluid.
Kidneys- paired bean-shaped organs located in the abdominal cavity on the sides of the spine at the lumbar level. The concave edge of the kidney faces the spine, the renal artery and renal vein, lymphatic vessels, nerves come here, and the ureter originates from here. The endocrine glands are adjacent to the upper part of the kidneys - adrenal glands. The bud has a dark outer layer ( cortex) and light inner part ( medulla). At the concave edge of the kidney there is a small cavity - pelvis. The ureter emerges from it, which connects the kidney to the bladder.

The structural unit of the kidney is nephron. Each kidney contains about 1 million nephrons. Nephron consists of capillary glomerulus, renal capsule and renal tubule. The cortical layer contains capillary glomeruli and renal capsules, and the medulla contains renal tubules. The capsule is a cup with a cavity inside, which contains the capillary (Malpighian) glomerulus. A convoluted tubule extends from the capsule, forming a loop and flowing into the collecting duct of the nephron. The collecting ducts merge to form larger excretory ducts.
The renal artery branches into afferent arterioles, which in turn divide into capillaries of the capillary glomerulus, which then gather into the efferent arteriole. The efferent arteriole again breaks up into a network of capillaries intertwining the convoluted tubules. After this, the capillaries connect into veins that flow into the renal vein. Thus, in the kidney there are two systems of capillaries: one is located inside the renal capsule, the other weaves around the renal tubule.
In the kidneys, urine is formed from substances carried by the blood. About 1,700 liters of blood flows through the kidneys during the day. The process of urine formation occurs in two phases: filtration(primary urine is formed) and reabsorption(secondary urine is formed).
In the first phase, primary urine is formed by filtering blood plasma from the capillaries of the glomerulus into the capsule cavity. This is possible due to the high hydrostatic pressure in the capillaries: 70–90 mmHg. Art. Primary urine- filtered blood plasma formed in the capsule cavity. The walls of the capillaries and the kidney capsule act as a filter, preventing the passage of blood cells and large protein molecules. Primary urine contains both unnecessary substances (urea, uric acid, etc.) and nutrients necessary for the body (amino acids, glucose, vitamins, salts, etc.). In 1 day, about 150 liters of primary urine are formed in the human body.
In the second phase, secondary urine is formed as a result of reabsorption(reabsorption) of water and other substances needed by the body back into the blood from primary urine, when it enters the renal tubule, densely braided with capillaries. Water, glucose, amino acids, vitamins, and some salts return to the blood. Reabsorption can occur passively as a result of diffusion and osmosis and actively due to the activity of the renal tubular epithelium. In secondary urine Only substances that the body does not need remain. As a result of the activity of the kidneys, about 1.5 liters of secondary urine are formed in 1 day. It contains 95% water and 5% solids: urea, uric acid, potassium salts, sodium salts, etc. During inflammatory processes in the kidneys and during intense muscular work, protein may appear in the urine.
The final urine passes from the tubules to the renal pelvis, from there to ureter and, thanks to the peristalsis of their walls, into the bladder. Bladder lies in the pelvic area. It is a bag with a thick wall, which greatly stretches when the bladder is filled. The outlet from the bladder is urethra closed by two muscular thickenings, which open only at the time of urination. Stretching the walls of the bladder (with an increase in its volume to 200–300 ml) leads to reflex urination. A person is able to consciously delay or perform the act of urination.
The activity of the kidneys is regulated by the nervous and humoral pathways. The sympathetic nervous system causes vasoconstriction in the kidneys, which reduces filtration. The parasympathetic system dilates the lumen of the kidney vessels and activates the reabsorption of glucose. Humoral regulation is carried out with the help of hormones. Hormone of the posterior lobe of the pituitary gland - vasopressin- enhances the reabsorption of water in the renal tubules. Adrenal cortex hormone aldosterone increases the reabsorption of Na + ions and the secretion of K + and H + in the tubules.
Impairment or cessation of kidney activity leads to poisoning of the body with substances that are usually excreted in the urine. The kidneys are sensitive to poisons produced by pathogens of infectious diseases, too spicy foods, and alcohol. When treating kidney diseases, it is possible to use an artificial kidney or transplant a healthy kidney from another person.

Blood

Functions of the circulatory system: respiratory(transfer of oxygen from lungs to tissues and carbon dioxide from tissues to lungs), nutritious(delivers nutrients to cells), excretory(removes unnecessary metabolic products), thermoregulatory(regulates body temperature by dilating and constricting blood vessels), protective(blood leukocytes destroy toxic substances and destroy pathogenic microbes that have entered the body), humoral(ensures the implementation of humoral regulation of body functions).

Motor analyzer

Receptors are excited when muscle fibers contract and relax. The organ of perception is the sensory cells in muscles, ligaments, and on the articular surfaces of bones.

Leather

The skin forms the outer covering of the body. The skin area is 1.5–1.6 m2, thickness - from 0.5 to 3–4 mm.
Skin functions: protective (from harmful influences and penetration of microorganisms); thermoregulation (through the blood vessels of the skin, sweat glands, subcutaneous fatty tissue: through the skin a person loses 85–90% of the heat generated in him); excretory (thanks to the sweat glands: sweat removes water, mineral salts and some organic compounds through the skin); receptor (the skin contains pain, temperature, and tactile receptors); blood depot (up to 1 liter of blood is deposited in the vessels of the skin); vitamin metabolism (the skin contains a precursor to vitamin D, which is converted into vitamin D under the influence of ultraviolet rays).
The skin consists of the epidermis and the skin itself - dermis. Adjacent to the dermis is the subcutaneous fatty tissue. Leather derivatives are hair, nails, sebaceous, sweat and mammary glands.
Epidermis It is represented by multilayered squamous keratinizing epithelium, in which five layers are distinguished. The deepest of them is basal layer. It is formed by basal skin cells capable of division, due to which all layers of the epidermis are renewed, and pigment cells containing the pigment melanin, which protects the human body from ultraviolet rays. The most superficial layer - the stratum corneum - consists of keratinized cells and is completely renewed in 7–11 days. The color of human skin depends on the amount of pigment contained in the cells of the epidermis.

Dermis (actual skin) has two layers: papillary and reticular. Papillary layer consists of loose connective tissue. The skin pattern depends on it. The papillary layer contains smooth muscle cells, blood and lymph vessels, and nerve endings. Mesh layer formed by dense connective tissue. Bundles of collagen and elastic fibers form a network and give the skin strength. This layer contains sweat and sebaceous glands and hair roots.
Behind the dermis is the subcutaneous layer fatty tissue. It consists of loose connective tissue containing fatty deposits.
Sweat glands concentrated at the border of the reticular layer and subcutaneous fatty tissue (about 2.5 million). The excretory ducts open into pores on the surface of the skin. The skin of the palms, soles of the feet, and armpits is rich in sweat glands. When sweating occurs, heat is transferred and metabolic products are removed. Water (98%), salts, uric acid, ammonia, urea, etc. are released with sweat.
Sebaceous glands located in the reticular layer, on the border with the papillary. Their excretory ducts open into the hair follicle. The secret of the sebaceous glands is sebum, which lubricates the hair and softens the skin, maintaining its elasticity.
Hair consists of a root and a rod. The hair root has an extension - the hair follicle, into which the hair papilla with vessels and nerves protrudes from below. Hair growth occurs due to cell division of the hair follicle. The hair root is surrounded by a hair follicle, to which the smooth muscle that lifts the hair is attached. At the point where the hair transitions into the shaft, a depression is formed - a hair funnel, into which the ducts of the sebaceous glands open. Kernel consists of keratinized cells containing air bubbles and melanin granules. With old age, the amount of pigment in keratinized cells decreases and the number of gas bubbles increases - the hair turns grey.
Nails- horny plates on the dorsal surface of the terminal phalanges. The nail lies in a bed of germinal epithelium and connective tissue. The skin of the nail bed is rich in blood vessels and nerve endings.
Hardening the body. Hardening increases immunity. Sun, air and water are the best natural hardening factors. They increase the body's resistance to adverse environmental conditions and various colds and infectious diseases.
Basic requirements for hardening: 1) gradualism (the temperature of water and air should be reduced when performing hardening procedures and their duration should be increased gradually); 2) systematic hardening (the body must be hardened from an early age until old age, since a break in hardening leads to the extinction of developed reactions); 3) a variety of hardening means (it is necessary to use various environmental factors, combine hardening with physical education and sports).

Reproduction and development

Reproduction- reproduction of one's own kind. Humans reproduce sexually. During sexual reproduction, the fusion of male and female reproductive cells occurs, as a result of which the future organism receives genetic information from both parents. Somatic cells of the human body have a diploid (double) set of chromosomes (23x2=46). Sex cells (sperm and eggs) contain a haploid (single), that is, a halved set of chromosomes (23). When a sperm merges with an egg during fertilization, a double set of chromosomes is restored, a zygote is formed, from which the child’s body develops.

Male reproductive system

The human male reproductive system is represented by the testes (testes), vas deferens, accessory sex glands (prostate gland, seminal vesicles) and penis. Testicles - paired organs located in the scrotum, skin-muscular sac, outside the body cavity. This is necessary for the normal course of spermatogenesis, which requires a temperature below body temperature. The testes form in the abdominal cavity and descend into the scrotum shortly before birth. Sperm and sex hormones are produced in the testes. Mature sperm are expelled from the testis into vas deferens as a result of muscle contractions. There they mingle with the secret prostate gland And seminal vesicles and form seminal fluid(sperm). Seminal fluid comes out through the urethra, which passes inside penis.

Female reproductive system

The human female reproductive system is represented by the testicles, fallopian tubes, uterus, vagina, labia majora and minora, and clitoris. Ovaries - paired organs located in the abdominal cavity. During the embryonic period, primary germ cells multiply in the ovaries. By the time they are born, their reproduction stops and they turn into first order oocytes. Each oocyte is surrounded by epithelial cells and forms a vesicle - follicle. Only a small proportion of a woman's ovarian oocytes mature during her fertile period (lasting from 12–13 to 50–55 years). As the oocyte grows, the follicular epithelium expands and a cavity with fluid appears in it. Occurs on average once every 28 days ovulation- a mature follicle ruptures and egg enters the abdominal cavity. As a rule, one follicle matures alternately in one or the other ovary. The immature egg enters fallopian tube(oviduct).

The movement of the egg through the fallopian tube is ensured by the vibration of the cilia of the epithelial cells of the fallopian tube and the peristaltic movements of its muscular wall. During the movement of the egg through the fallopian tube, its final maturation occurs (second meiotic division). Here the egg can be fertilized by a sperm. Fertilized egg ( zygote) begins to divide and an embryo is formed. It enters the uterus and penetrates its mucous membrane. If fertilization does not occur, the egg is destroyed as it passes through the uterus.
Uterus - a hollow, pear-shaped muscular organ lined with mucous membrane. An embryo develops in it. During childbirth, contraction of the muscles of the uterus pushes the fetus out. The uterus ends neck , somewhat protruding into the vagina and opening into it. The cervix contains the most powerful sphincters (circular muscles) of the human body. They hold the fetus and amniotic fluid in the uterus until the baby is born.
Vagina - a muscular tube extending from the uterus to the outside. It serves for the passage of semen during sexual intercourse and as the birth canal during childbirth. The entrance to the vagina is located between the skin folds - labia (big and small). At the anterior junction of the labia there is clitoris - a sensitive organ the size of a pea. The entrance to the vagina in girls is closed with a connective tissue film - hymen . Near the entrance to the vagina is the opening of the urethra.
As a rule, uterine bleeding occurs every 28 days in women who have reached puberty - menses. Each cycle, a follicle begins to mature in one of the ovaries. Its final maturation ends with ovulation - the release of an egg (usually on the 12th–17th day of the menstrual cycle). The cells of the destroyed follicle grow and form corpus luteum- temporary endocrine gland in the ovary. The corpus luteum secretes the hormone progesterone, which delays the maturation of the next follicle and prepares the uterine mucosa to receive the embryo. If fertilization of the egg does not occur, then the corpus luteum stops secreting progesterone on the 13th–14th day after ovulation. With a decrease in the amount of progesterone and estrogen, the corpus luteum undergoes reverse development. The uterine mucosa is rejected, the dilated blood vessels of the uterus are opened, and pieces of the mucosa along with blood enter the vagina. Menstruation lasts from 3 to 5 days. Then the uterine lining is restored. In the absence of corpus luteum hormones, the cycle repeats.
The beginning of the cycle is considered to be the 1st day of menstruation. There are three periods in the menstrual cycle: menstruation- rejection of the uterine mucosa and uterine bleeding (3–5 days); postmenstrual- the uterine mucosa is restored, another follicle grows in the ovary (from the 5th to the 14th–15th day); premenstrual- ovulation, the formation of the corpus luteum, which produces progesterone.
Fertilization is possible within 12–24 hours after ovulation, as long as the egg remains viable. Spermatozoa are capable of fertilization within 2–4 days.

Development of the organism

Human development is divided into two periods: embryonic and postembryonic.
Embryonic (intrauterine) period Human development lasts on average 280 days. It is divided into three periods: initial (1st week of development), embryonic (2–8th weeks), fetal (from the 9th week of development until the birth of the child).
Initial period. During sexual intercourse, 2–5 ml of sperm enters the vagina, which contains from 30 to 100 million sperm in 1 ml. Only a few million sperm penetrate into the uterine cavity, and only about 100 reach the upper part of the fallopian tube. Their transport lasts 5–30 hours. Fertilization usually occurs at the beginning of the fallopian tube. Then the zygote moves through the tube into the uterus (at this time, crushing occurs and a blastula is formed). After 5–5.5 days, the blastula enters the uterus; on the 6–7th day, its implantation occurs - immersion in the mucous membrane of the uterus and subsequent attachment to it.
Germinal period. Nutrition of the embryo and gas exchange are carried out through the placenta, which begins to form on the 14th day and is formed by the end of the 2nd month of intrauterine development. The blood of the mother and fetus does not mix, and nutrition and the release of dissimilation products and gas exchange occur diffusely. The placenta looks like a disc embedded in the lining of the uterus. At the end of the 3rd week, the embryo begins to develop organs: the nervous, digestive, circulatory and other systems are formed. In the 5th week, the rudiments of arms and legs are formed. Between the 6th and 8th weeks, facial features are outlined, the eyes shift from the lateral surface to the front. By the 8th week, the laying of organs ends. The embryo has a length of 4 cm and a mass of 5 g.
Fetal period begins from the 9th week of intrauterine development and is characterized by the formation of the structure and functions of the organs and systems of the fetus. At the end of the second month, the head and torso are differentiated, and the third - the limbs. In the fifth month, the mother begins to feel the movements of the fetus, and the heartbeat can be heard. At the end of the sixth month, internal organs mature. At the 8th month, the fetus is viable, but needs conditions for intrauterine development. At the time of birth (intrauterine age 40 weeks), the fetus weighs at least 2500 g and is at least 47 cm long.
Childbirth. Pregnancy lasts about 9 months and ends with childbirth, which is divided into three periods. First period - cervical dilatation- lasts from 2 to 20 hours. Second period - fetal expulsion- lasts from 2 to 100 minutes. The birth of a child occurs as a result of contraction of the muscles of the uterus. From the first cry of a newborn, oxygen begins to flow into his blood through the lungs. After this, the doctor ties the umbilical cord. Third period - delivery of the placenta- begins 15–20 minutes after the birth of the child. The uterus continues to contract, the placenta separates from the uterus and, together with the remains of the umbilical cord and membranes of the fetus, comes out.
Postembryonic period Child development is divided into the following periods: newborns(first 4 weeks after birth); chest(from the 4th week to the end of the 1st year of life); nursery or preschool(from 1 to 3 years); preschool(from 3 to 6 years); school(from 6 to 17–18 years old).
During the neonatal period, in infancy and toddlerhood, the child experiences an acceleration in the formation of brain structures. This leads to an increase in the child’s cognitive capabilities both in the preschool and preschool periods (from 3 to 7 years).
The school period is characterized by the completion of differentiation of the cells of the cerebral hemispheres, which creates conditions for higher forms of brain activity (analytical-synthetic). The period of puberty (puberty) in girls lasts from 12 to 16 years, in boys from 13 to 17–18 years and is accompanied by the most complex changes in the body, preparation for reproductive function. During this period, the highest rates of growth and weight gain are observed.
Puberty is the result of increased hormonal function in the “hypothalamus - pituitary gland - adrenal glands - gonads” system. The consequence of this is an increase in the level of sex hormones in the blood.
From the age of 12–13, boys experience the development of secondary sexual characteristics: pubic hair appears, after 2 years - hair in the armpits and on the face, growth of the cartilage of the larynx occurs, followed by a break in the voice. The shoulders become wider, but the pelvis remains narrow. In girls aged 10–12 years, pubic hair growth, swelling in the nipple area, and hair growth in the armpits are observed; The pelvic bones expand, the shoulders remain narrow. The first menstruation coincides with the end of the maximum rate of growth in length. During the year after the first menstruation, there is a period of relative infertility, since the first menstruation does not always precede the release of the egg from the ovary.
During adolescence (17–21 years for boys and 16–20 years for girls), the body continues to grow in length (1–2 cm per year), and the formation of organ systems is completed.

The human body is a single biological system

Fabrics. The structure and vital functions of organs and organ systems: digestion, respiration, excretion.

The structure and vital functions of organs and organ systems: musculoskeletal, integumentary, blood circulation, lymph circulation. Human reproduction and development.

Internal environment of the human body. Blood groups. Blood transfusion. Immunity. Metabolism and energy conversion in the human body. Vitamins, their role in the body.

Neurohumoral regulation of functions in the human body.

Nervous system, structure, functions, classification.

Endocrine system, structure, functions. Neurohumoral regulation of the body's vital processes as the basis of its integrity and connection with the environment.

Analyzers. Sense organs, their role in the body. Structure and functions. Higher nervous activity. Sleep and wakefulness, meaning. Consciousness, memory, emotions, speech, thinking. Features of the human psyche.

Modern concept of a healthy lifestyle

Personal and public hygiene, healthy lifestyle. Prevention of infectious diseases (viral, bacterial, fungal, caused by animals). Injury prevention, first aid techniques.

Mental and physical health of a person. Health factors (auto-training, hardening, physical activity). Health risk factors (stress, physical inactivity, overwork, environmental pollution). Compliance with sanitary and hygienic standards and rules of a healthy lifestyle. The influence of alcohol, nicotine, and drugs on the human body.

Evolution of living nature

Superorganismal systems of living nature.

Type, its criteria. A population is a structural unit of a species and an elementary unit of evolution. Microevolution. Formation of new species.

Development of evolutionary ideas. The meaning of Charles Darwin's evolutionary theory. Interrelation of the driving forces of evolution. Forms of natural selection, types of struggle for existence. Synthetic theory of evolution.

Evidence of the evolution of living nature. Results of evolution: adaptability of organisms to their environment, diversity of species.

Macroevolution. Directions and paths of evolution (A. N. Severtsov, I. I. Shmalgauzen). Biological progress and regression, aromorphosis, idioadaptation, degeneration. Causes of biological progress and regression. Hypotheses of the origin of life on Earth.

Human Origins.

Man as a species, his place in the system of the organic world. Hypotheses of human origin. Driving forces and stages of human evolution. Human races, their genetic relatedness. Biosocial nature of man. Social and natural environment, human adaptation to it.

Ecosystems and their inherent patterns

Interaction of organisms with their environment.

Habitats of organisms. Ecological factors: abiotic, biotic, anthropogenic, their significance.

Ecosystem (biogeocenosis), its components: producers, consumers, decomposers, their role. Species and spatial structure of the ecosystem. Trophic levels. Chains and power networks, their links. Rules of the ecological pyramid. Drawing up diagrams of the transfer of substances and energy (circuits and power networks).

Diversity of ecosystems (biogeocenoses). Self-development and change of ecosystems. Stability and dynamics of ecosystems. Reasons for stability and change of ecosystems. Changes in ecosystems under the influence of human activities. Agroecosystems.

The biosphere is a global ecosystem. The doctrine of V.I. Vernadsky about the biosphere. Evolution of the biosphere.

PROCEDURE FOR CONDUCTING ENTRANCE TESTS.

The biology exam is conducted in written form as a test.

Questions to prepare for entrance tests in biology

1. Amoeba, its structure and vital functions.

2. Protein biosynthesis.

3. Biosphere and its boundaries. V.I. Vernadsky about the emergence of the biosphere.

4. Biosphere, its boundaries, composition. The circulation of substances and the transformation of energy in the biosphere.

5. Biotechnology, its achievements and ethical aspects of some research in biotechnology (cloning).

6. Types of muscle tissue in the body, their characteristics.

7. Viruses, features of their structure and life activity. AIDS virus. Prevention of AIDS.

8. Contribution of K. Linnaeus to the development of evolutionary theory.

9. Gene, its connection with the DNA molecule. Human chromosome set

10. Genetics as a science. The importance of genetics for medicine and breeding.

11. Genetics of sex. Examples of hereditary diseases associated with gender.

12. Genetic code and the process of matrix protein synthesis.

13. Fragmentation of the zygote. Formation of germ layers.

14. Wildlife as an object of study of biology. The main signs of living things. Levels of organization of living nature.

15. Patterns of modification variability.

16. Mendel's laws.

17. Replaceable and essential amino acids, their role. Encoding of amino acids by a DNA molecule.

18. Individual development of organisms (ontogenesis).

19. Class of amphibians. Features of the external and internal structure using the example of a frog.

20. Class of arachnids. Class characteristics.

21. Fish class. Internal structure using the example of river perch.

22. Cellular organelles, their characteristics.

23. Skin, its structure and functions.

24. Type criterion. Populations, their characteristics.

25. Blood, blood composition, blood cells. Functions of blood in the body.

26. Meiosis, its characteristics. Behavior of chromosomes during meiosis.

27. Methods of knowledge of living nature.

28. Modification variability. Norm of reaction.

29. Neuron, its structure. Types of nerve cells.

30. General characteristics of the class of mammals.

32. General characteristics of human tissue types.

33. Fertilization and its significance.

34. The organ of hearing, its structure and functions.

35. Human respiratory organs, their structure and functions.

36. Main directions of the evolutionary process: aromorphosis, idioadaptation, general degeneration. Examples of basic aromorphoses.

37. The main provisions of the evolutionary teachings of Charles Darwin.

39. Liver, pancreas and their role in human digestion.

40. Plastic and energy metabolism are two sides of a single metabolic process.

41. Gonads, germ cells.

42. The concept of an analyzer. The meaning of the senses.

43. The concept of biopolymers. The structure of proteins, their role in the body.

44. The concept of genotype and phenotype. The role of the external environment in the formation of the phenotype.

45. The concept of heterosis. Polyploidy and distant hybridization in plant breeding.

46. ​​The concept of a reflex arc. Examples of a monosynaptic reflex.

47. The concept of the central nervous system and peripheral nervous system. Divisions of the peripheral nervous system

48. Ecological pyramid rule.

49. Adaptation to the environment, its relative nature. Examples of adaptations in nature

50. Development of knowledge about the cell. Basic principles of cell theory.

51. RNA, structure. Types of RNA. Differences in the structure of RNA and DNA molecules.

52. The role of humoral regulation in the body. The main endocrine glands.

53. The role of J.-B. Lamarck in the formation of evolutionary ideas.

54. Modern ideas about the origin of life on Earth. Oparin's theory

55. Comparative anatomical evidence of macroevolution. A unified structural plan of vertebrates, homologous and similar organs, rudiments, atavisms.

56. Structure of the eye. Myopia concept.

57. Structure and functions of the spinal cord. Spinal cord section.

58. Structure and chemical composition of the cell.

59. The structure of the cell membrane. The role of lipids and proteins in the membrane.

60. Structure of the heart. Systemic human circulation.

61. The structure of the retina, the role of rods and cones.

62. Structure of the human skeleton.

63. The essence of selection and its main methods.

64. Type of coelenterates, its characteristics. Structural features using the example of Hydra.

65. Three stages of energy metabolism, their characteristics.

66. Conditioned and unconditioned reflexes. The role of I.P. Pavlov in the creation of the doctrine of higher nervous activity.

We take care of our health from an early age -
It will save us from pain and troubles.

Goals. Summarize and systematize students’ knowledge about the human body; develop the ability to systematize educational information in crossword puzzles; learn to work in a group, defend your opinion, listen to the opinions of your comrades; cultivate a careful attitude towards your health.

Educational material. Crosswords “Human Organism”, “Skeleton”; Handout; tables on the topic “The human body and its health.”

Leading. Today we have gathered to summarize our knowledge on the topic we have studied. Two teams take part in the game.

Announcement of teams, introduction of captains and jury members.

– Our game consists of five rounds. Each round is evaluated by a jury. Captains, get ready for the draw.

Round 1. “Warm-up”

1. What knowledge was valued in ancient times? What was the healer an expert in? ( Expert in diseases and their treatment. This knowledge was highly valued among people; Life depended on them.)

2. If a person turned into a tree, what would his torso, arms, legs become? ( The torso and neck would turn into a trunk, the legs into roots, and the arms into branches and leaves.)

3. At what age were you most like animals? ( In infants, until they could walk and crawled on all fours.)

4. Which animal has eight legs and two body parts? ( At the spider's.)

5. What kind of person, the hero of the fairy tale, became the king of animals? Whereby? ( The hero of R. Kipling's fairy tale Mowgli became the king of animals after he learned to use fire.)

6. What three names for parts of the skeleton does a person use on the farm? ( Shoulder blade, hand, pelvis.)

7. What danger did the princess and the pea expose her spine to? ( On a very soft bed, the spine bends greatly and may become curved over time.)

8. What animals do not have a backbone? What can you call such animals? ( Invertebrates: insects, worms, snails, octopuses, jellyfish.)

9. The outer covering of the body - the skin - is the largest human organ. The skin protects the body from damage, retains fluids and prevents harmful substances from entering the body. The skin behaves very strangely in the cold - it turns pale, and during the heat it turns red. Why is this happening? ( In the cold, blood rushes deep into the body to warm the internal organs. And the skin turns pale. During heat, blood enters the capillaries on the surface of the skin. This removes excess heat from the body.)

This is interesting!

Leather had the original sound - goat's skin ("skin") and came from the word goat. Subsequently, the sound [z] changed to [zh]. With the replacement of the sound, the meaning expanded greatly: leather began to mean any processed skin, and then our skin, and the word goat was forgotten.

The jury sums up and announces the results of the first round.

Tour 2. “Human Organism”

Leading. Now it's a round of riddles. The captains take the text of the riddles, read them aloud to the team and guess. For a correct answer, the team receives 1 point.

Puzzles

I'll open the stable
I will release a flock of white sheep.
When we eat they work
When we don't eat, they rest,
If we don't clean them, they'll get sick. ( Teeth.)

Pit with red edges.
Motionless in this hole
In two rows above a row
The white stakes are standing. ( Mouth, teeth.)

If it weren't for him,
I wouldn't say anything.
Always in my mouth
But you won't swallow it.
He's always at work
When we speak,
And he’s resting
When we are silent. ( Language.)

A small bag hangs -
Sometimes full, sometimes empty.
The carriages are running towards it,
They are bringing food and liquids.
Work is in full swing all day long,
We are not too lazy to help him.
Prepares food, feeds us,
And what is not needed, he kicks out. ( Stomach.)

Two beans are hanging
Unnecessary substances are passed through
And they help remove them. ( Kidneys.)

This is interesting

How many times is blood “washed” in the kidneys?

During the day, blood passes through the kidneys for purification about 300 times.

I cover my body from above,
I protect and breathe
I sweat out,
I control the temperature. ( Leather.)

This is interesting

The skin is the largest organ of the body, its main part. Doctors say that the skin weighs about 4 kg and would occupy 2 square meters. m.

It turns out that for 1 sq. cm of dirty skin there are about 40,000 microbes.

They see the whole world
But not each other.
What is this? ( Eyes.)

This is interesting

What is called mind's vision? ( A person's ability to imagine and see scenes and images with their eyes closed.)

Why are there eyelashes around the eyes? ( They protect the eyes from debris.)

Why do we blink? ( In order to periodically wet the cornea with tears.)

What is a pupil? ( The pupil is the hole through which light enters the eye to reach the light-sensitive organ, the retina..)

Behind the bone wall,
Soloveyko, sing. ( Language.)

We connected all the body parts,
They called us cobwebs... ( Nerves.)

He remembers everything
Watch, listen, talk,
Seeing helps
It controls the functioning of our entire body. ( Brain.)

Every face has
Two beautiful lakes.
There is a mountain between them.
Name them, kids. ( Eyes and nose.)

Some believe that it is needed for decoration. Others think that it is needed only to lift it up when you put on airs. In fact, it is a filter, a stove, and a guard post. ( Nose.)

It knocks day and night,
It's like it's a routine.
It will be bad if suddenly
This knocking will stop. ( Heart.)

This is interesting

The heart is a muscular organ that ensures blood flow through the vessels. The mass of the adult heart is 250–300 g. Its size is approximately the same as a human fist.

If our heart pumped not blood, but water, then in 70 years a lake 2.5 m deep, 7 m wide, and 10 km long would form.

In a person who moves from an open area to a green area, the pulse rate can decrease by almost 20 beats per minute.

Muscles resemble little mice that run under the skin, and the word muscle itself is very similar to the word mouse. The word muscle comes from the Latin muscle, that is, “little mouse.”

Muscles make up approximately 2/5 of the total body weight.

The largest muscle is the gluteus, which forms the buttocks. It is needed to pull the leg back and the body forward while walking, running and jumping.

The smallest muscle is the stapedius, located deep in the ear.

What doesn't rest in the body when you sleep? ( The heart never rests.)

Crossword "Human Organism"

1. Digestive organ. 2. Circulatory organ. 3. Organ of vision. 4. Organ of touch. 5. Olfactory organ. 6. Respiratory organs. 7. Central part of the nervous system. 8. An organ that allows a person to move.

ANSWERS: 1. Mouth. 2. Heart. 3. Eye. 4. Leather. 5. Nose. 6. Lungs. 7. Brain. 8. Muscle.

In the selected cells horizontally: ORGANISM .

Round 3. “An extra word”

Leading. The tasks of the third round will test your knowledge, ability to compare, generalize and draw conclusions. Attention! Captains get assignments!

Teamwork.

Game "Find the odd one out"

Eyes, nose, heart;

lungs, stomach, nasopharynx;

esophagus, blood, stomach;

kidneys, skull, spine.

Eyes, artery, heart;

bronchi, kidneys, nasopharynx;

red blood cells, blood, stomach;

kidneys, skull, ribs.

Liver, blood, brain;

nerve, brain, joint;

stomach, esophagus, lungs;

nose, lungs, intestines.

Leading. Musical pause. The jury's word.

We continue our competition. Now your task is to guess which human organ we are talking about.

Game “Find out by description”

This is a muscular tube about 20 cm long that propels crushed and moistened food through itself. ( Esophagus.)

Clothes that do not get wet, do not wrinkle, and do not fade. You can wear it for at least a hundred years. ( Leather.)

They consist of bubbles, have no muscles, but are able to stretch, increasing their volume, and contract, reducing it. ( Lungs.)

The body's main command post. ( Brain.)On average, the brain weighs 1.4 kg; Each part of the brain does its own job. These areas are called centers.)

The main compartment of your “inner kitchen”. ( Stomach.)

This is interesting

The word stomach is derived from the word acorn (in the old days small acorns were called stomachs): in some animals it looks like an acorn.

This organ is called the dispatcher, as it closely monitors the composition of the blood. ( Liver.)

It helps us make the necessary sounds, helps us eat. He carefully turns over the food you are chewing and places it under one or another of your teeth. ( Language.)

This is a muscle pump. During one contraction it releases up to 100 grams of substance. Makes an average of 70 beats per minute. Located on the left side of the chest. ( Heart.)

On a warship, the thickest steel walls reliably cover the conning tower, where the ship's command post is located. Your brain is the command center of your body. And nature protects it as carefully as sailors protect their conning tower. What conning tower are we talking about? ( About the skull.)

Leading. The jury gives the floor.

Round 4. “Question and answer”

Leading. Our tour consists of questions and short answers.

1. Why were the lungs called that? ( It was not by chance that the respiratory organ was named this way: the lung tissue, permeated with air bubbles, is much lighter than muscle tissue.)

2. At what time of year is a long nose healthier than a short one? ( In winter, when it is important for the body to warm up the air inhaled through the nose.)

3. Is salt removed from the body? ( To remove salt from an “over-salted” body, it is best to take a steam bath, go for a long run, play football or basketball to get a good sweat.)

4. Why is a slap on the head dangerous? ( Concussion. In the occipital region of the brain there is a center of vision that can be damaged by a blow.)

5. By what signs can a specific person be identified? ( According to the patterns on the fingertips.)

6. Why do humans have so many muscles? ( More than 600 muscles perform all movements, including winking. Even the beating of the heart or the activity of the intestines occurs with the help of muscles. Muscles make up almost half of the body's weight.)

7. Whose muscles are stronger: a human or an ant? ( The ant is 20 times stronger.)

8. Why is blood called the body’s transport system? ( Red blood cells carry nutrients and oxygen needed by the body. White blood cells fight disease. Blood carries away decay products from cells and delivers them to the excretory organs.)

This is interesting

If all the red blood cells of one person were placed side by side, the result would be a ribbon that encircles the globe three times along the equator.

Leukocytes live 4–5 days, and more and more “glorious warriors” come to replace them.

A child’s body contains about 3 liters of blood, 2 liters of which is plasma.

9. How does the body cleanse itself? ( The elimination of waste and harmful substances from the body occurs in various ways - through breathing, sweat, urine and feces..)

10. What does the liver do? ( Participates in the digestion process, removes poisons from the body, accumulates useful substances.)

11. What are the functions of sweat glands? ( The skin removes excess water and salts from the body. Sweat evaporates from the surface of the skin and thereby cools it.)

12. Is it possible to replace diseased body parts? ( Yes, for example, a joint, some blood vessels, internal organs - heart, liver, kidneys.)

13. Name the main command center of the body. ( Brain.)

Leading. The jury gives the floor. Musical pause.

Round 5. “The most, the most...”

Leading. This competition is a kind of book of records for the body. The first team to give the correct answer will receive 1 point. Attention!

1. Name the largest internal organ. ( Liver.)

2. Name the largest external organ. ( Leather.)

3. Name the longest human bone. ( Femoral, approximately 46 cm: starts from the pelvis and ends near the knee. Approximately equal? total body length.)

4. Name the smallest bone in the body. ( Stirrup – length 3–5 mm; located in the inner ear.)

5. Name the widest bone. ( Pelvic.)

6. Which organ is the longest in our body? ( 6-meter small intestine.)

7. Which organ never rests? ( Heart.)

8. How fast does it beat? ( 60–75 beats per minute.)

Leading. The jury speaks, then the final test.

Round 6. “Practice”

Leading. Now each team will complete the “Skeleton” crossword puzzle. Be very careful, don't rush.

Crossword Questions

1. A part of the leg that contains many small bones. 2. The scientific name for the “little tail” of the spine. 3. The name of the arcuate bones extending from the spine. 4. One of the components of the shoulder. 5. The part of the arm between the humerus and the hand. 6. Components of the skeleton. 7. What protects the brain from damage. 8. Part of the leg from the knee to the foot. 9. What do the scapula and collarbone form? 10. The main purpose of the skeleton. 11. What comes from the skull along the back? 12. Bone damage. 13. Part of the hand with many small bones. 14. Body position when walking, sitting.

ANSWERS

1. Foot. 2. Coccyx. 3. Rib. 4. Spatula. 5. Forearm. 6. Bones. 7. Skull. 8. Shin. 9. Shoulder. 10. Support. 11. Spine. 12. Fracture. 13. Brush. 14. Posture.

– What words are in the highlighted cells?

Children: Human skeleton.

The crossword puzzle can be replaced with practical work: assemble a paper human skeleton from parts, gluing them onto a single sheet of paper.(See the workbook for the textbook by O.T. Poglazova “The world around us” for 3rd grade of educational institutions, part 2, p. 63.)

Leading. Well done boys! You have passed all the tests. The jury's word.

Awarding the winners and distinguished players.

Literature

Pil A. My body Per. with him. V. Volkova. – M.: Astrel; AST. 2002. 64 p.
Parker S., Williams B. Question and answer. Live nature. Human body: encycl. Per. from English – M.: Omega, 2006. 64 p.
Poglazova O.T. Methodological recommendations for the textbook “The World around us”: 3rd grade: textbook. allowance for general education. Institutions. 2nd ed. Smolensk: Association XXI century, 2007. – 336 p.
The world. Grade 3: lesson plans based on the textbook by O.T. Poglazovoy, V.D. Shilina. Part II / Author-comp. T.V. Bondareva. Volgograd: Teacher, 2007. 383 p.
Sukharevskaya E.Yu. Entertaining natural history. Life on Earth: educational method. allowance for primary teachers schools, pedagogical students textbook institutions, IPK students. – Rostov n/d: Teacher, 2003. 128 p.

5.1. Fabrics. The structure and vital functions of organs and organ systems: digestion, respiration, blood circulation, lymphatic system.

5.1.1. Human anatomy and physiology. Fabrics.

5.1.2. Structure and functions of the digestive system.

5.1.3.Structure and functions of the respiratory system.

5.1.4. Structure and functions of the excretory system.

5.2. The structure and vital functions of organs and organ systems: musculoskeletal, integumentary, blood circulation, lymph circulation. Human reproduction and development.

5.2.1. Structure and functions of the musculoskeletal system.

5.2.2. Skin, its structure and functions.

5.2.3. Structure and functions of the circulatory and lymphatic system.

5.2.4. Reproduction and development of the human body.

5.3. Internal environment of the human body. Blood groups. Blood transfusion. Immunity. Metabolism and energy conversion in the human body. Vitamins.

5.3.1. Internal environment of the body. Composition and functions of blood. Blood groups. Blood transfusion. Immunity.

5.3.2. Metabolism in the human body.

5.4. Nervous and endocrine systems. Neurohumoral regulation of the body's vital processes as the basis of its integrity and connection with the environment.

5.4.1. Nervous system. General plan of the building. Functions.

5.4.2. Structure and functions of the central nervous system.

5.4.3. Structure and functions of the autonomic nervous system.

5.4.4. Endocrine system. Neurohumoral regulation of vital processes.

5.5. Analyzers. Sense organs, their role in the body. Structure and functions. Higher nervous activity. Dream, its meaning. Consciousness, memory, emotions, speech, thinking. Features of the human psyche.

5.5.1 Sense organs (analyzers). Structure and functions of the organs of vision and hearing.

5.5.2.Higher nervous activity. Dream, its meaning. Consciousness, memory, emotions, speech, thinking. Features of the human psyche.

5.6. Personal and public hygiene, healthy lifestyle. Prevention of infectious diseases (viral, bacterial, fungal, caused by animals). Injury prevention, first aid techniques. Mental and physical health of a person. Health factors (auto-training, hardening, physical activity). Risk factors (stress, physical inactivity, overwork, hypothermia). Bad and good habits. Dependence of human health on the state of the environment. Compliance with sanitary and hygienic standards and rules of a healthy lifestyle.

5.1. Fabrics. The structure and vital functions of organs and organ systems: digestion, respiration, blood circulation, lymphatic system.

5.1.1. Human anatomy and physiology. Fabrics.

5.1.2. Structure and functions of the digestive system.

5.1.3.Structure and functions of the respiratory system.

5.1.4. Structure and functions of the excretory system.

Fabrics

Tissue is a collection of cells and intercellular substance, united by a common structure and origin, as well as the functions they perform.

There are four main types of tissue in humans and animals: epithelial, muscular, nervous and connective.

Epithelial tissue, or epithelium(Fig. 5.1), covers the body, lines all the cavities of the internal organs and forms various glands. It performs protective, respiratory, suction, excretory, secretory and other functions. The cells of epithelial tissue are tightly adjacent to each other, there is little or no intercellular substance in it, and it is necessarily underlain by connective tissue.

Based on their location and functions, epithelia are divided into glandular and superficial. Glandular epithelia are the basis of the internal and external secretion glands, for example, lacrimal, salivary, thyroid, etc. They are capable of producing a variety of products - secretions, for example tear fluid, digestive enzymes and hormones.

Surface epithelia Based on the number of cell layers, they are divided into single-layer and multilayer, and according to the shape of the cells - into flat, cubic, prismatic, ciliated, etc. Multilayer epithelia are also classified as keratinizing and non-keratinizing. Thus, stratified squamous keratinizing epithelium covers our body and is called the epidermis of the skin, and non-keratinizing epithelium lines, for example, the oral cavity.

Connective tissue fills all the spaces between organs and other tissues and makes up more than 50% of the human body weight (Fig. 5.2). A distinctive feature of its structure is the presence of a large amount of intercellular substance and a significant variety of cellular elements. The intercellular substance of connective tissue consists of collagen and elastic protein fibers, as well as amorphous substance. This type of tissue performs nutritional, transport, protective, supporting, plastic and structure-forming functions in the body.

Connective tissue was previously divided into connective tissues proper, skeletal and nutritional, or trophic (blood and lymph), however, according to modern classifications, blood and lymph are separated into a separate type of tissue.

The connective tissues themselves include dense fibrous tissues of tendons and ligaments, fibrous connective tissue, as well as reticular and adipose tissue. The intercellular substance of dense fibrous tissue is dominated by collagen and elastic fibers; ligaments and tendons are composed of it. The loose fibrous connective tissue is dominated by amorphous substance; it accompanies the vessels, forms the dermis and some organs. Reticular tissue forms a kind of network of fibers and process cells in the red bone marrow, spleen, lymph nodes, etc. It plays an important role in the process of hematopoiesis. Adipose tissue is formed by fat cells and makes up the subcutaneous fatty tissue and the layers between the internal organs.

Skeletal connective tissues are represented by bone and cartilage. Skeletal bones and dental tissue are formed from the first. The intercellular substance of bone tissue contains up to 70% mineral salts, especially calcium phosphate, which gives it strength, about 20% water and proteins. The cells of this tissue are osteocytes- immured in plates of intercellular substance and connected to each other by processes.

Cartilaginous tissue connects the bones of the skeleton, forms articular surfaces, forms the respiratory tract, auricle, wings of the nose, etc. Its intercellular substance is highly hydrated and is dominated by collagen fibers. The main cells of cartilage tissue are chondrocytes, they are located in groups in the intercellular substance.

Muscle tissue is a type of tissue whose distinctive feature is excitability and contractility.

The contraction of muscle tissue is caused by the interaction of actin and myosin microfilaments. Elements of muscle tissue usually have an elongated shape. They provide movement of the human body and contraction of the walls of internal organs and take part in the implementation of some of the most important vital functions. Muscle tissues of the body are divided into smooth and striated. Skeletal and cardiac muscle tissues are classified as striated. The striation of striated muscle tissue is caused by the superposition of alternating actin and myosin microfilaments.

Smooth muscle cells - myocytes- have a spindle shape and a single rod-shaped nucleus (Fig. 5.3). Myocyte contractions are rhythmic and do not depend on human consciousness, which is why this tissue is also called involuntary. This type of tissue lies in the walls of internal muscular organs, such as the esophagus, stomach, bladder, arteries, etc.

The structural units of striated skeletal muscle tissue are multinucleated muscle fibers with characteristic striations. This tissue forms the skeletal and facial muscles, muscles of the mouth, tongue, larynx, upper esophagus and diaphragm.

Striated cardiac muscle tissue consists of striated muscle cells - cardiomyocytes- with one or two cores (Fig. 5.4). Thanks to special cellular contacts, it is able to contract simultaneously. Striated cardiac tissue forms the middle layer of the heart wall - the myocardium.

Nervous tissue ensures the integration of parts of the body into a single whole, the regulation and coordination of their activities, the interaction of the body with the environment, and in humans, also thinking, consciousness and speech. The main properties of nervous tissue are excitability and conductivity. Nerve tissue cells adhere tightly to each other. The main type of cells in nervous tissue are neurons capable of excitation (formation of nerve impulses) and its conduction (Fig. 5.5).

Neurons consist of a body and processes. The processes along which the nerve impulse enters the neuron are called dendrites, and transmitting it to other cells - axons.

The transmission of information in the form of a nerve impulse from one neuron to another or to other cells occurs through a special type of cellular contacts - slit-like synapses(Fig. 5.6). The neuron transmitting the impulse is released by exocytosis of a special substance - mediator, which is perceived by the next cell and causes its reaction (excitation or inhibition). Accordingly, depending on the nature of the action, synapses are divided into excitatory and inhibitory. Some nerve cells are capable of releasing hormones into the bloodstream, they are called neurosecretory.

Nutrition, protection and insulation of neurons from each other are functions of cells neuroglia, which fills all the gaps between neurons.

Nervous tissue is the main structural and functional element of the nervous system; it forms the brain and spinal cord, as well as nerves and ganglia.

The structure and functioning of the organs of the digestive system

Digestion called a set of processes of mechanical grinding and chemical breakdown of food, which makes its components suitable for absorption and use in the metabolic process. This function is performed by the digestive system. In addition, it also ensures the removal of undigested food debris, the release of toxic metabolic products and the maintenance of immunity.

Digestive system human is formed by the digestive canal and accompanying glands. The total length of the digestive canal is 8-10 m, it is divided into three sections: anterior, middle and posterior. In the anterior section, mainly mechanical processing of food is carried out, in the middle - chemical breakdown, absorption and formation of feces, and in the posterior section they accumulate and are removed from time to time. The anterior section consists of the oral cavity, pharynx and esophagus, the middle section includes the stomach, small and large intestines, and the posterior section is represented by part of the rectum (Fig. 5.7).

Oral cavity is divided into the vestibule of the mouth, or pre-oral cavity, and the oral cavity itself. In front, the vestibule of the mouth is limited by the cheeks and lips, and behind by the teeth. The mouth opening leads into it. The lips and cheeks are folds of skin with a muscular underlay of the orbicularis oris and buccal muscles. The lips provide perception of the temperature and consistency of food.

A child has 20 baby teeth, and an adult has 32 permanent teeth. The process of changing teeth is completed by the age of 12-14 years.

Constant tooth has a crown, neck and roots (Fig. 5.8).

The crown is covered with enamel, and the roots are covered with cement; under them lies a layer of bone tissue - dentin. The middle of the tooth occupies pulp, in which the blood vessels that provide nutrition to the tooth tissues and nerve endings are located.

On each jaw of an adult there are 4 incisors, 2 canines, 4 small molars and 6 large molars. The last molars are called “wisdom teeth”, since they grow the latest, by the age of 20-25.

With the help of teeth, food is divided into pieces, crushed and chewed.

The most common dental disease is caries, which is caused by bacteria that live in the mouth. These bacteria produce acid that destroys tooth enamel. Eating hot and cold food contributes to caries to a large extent. Caries can cause the development of diseases of both the digestive system and other organ systems.

The oral cavity itself is limited in front and on the sides by the teeth, on top by the hard and soft palate, and below by the diaphragm of the mouth on which the tongue rests. The salivary glands open into it, as well as into the vestibule of the mouth.

Humans have three pairs of large salivary glands- parotid, sublingual and submandibular, as well as numerous small glands of the cheeks, tongue and palate. They produce saliva containing about 99% water and mineral salts and proteins dissolved in it. An important role among salivary proteins is played by the enzymes amylase and ptyalin, which begin the breakdown of carbohydrate-polysaccharides, as well as lysozyme, which disinfects food. In addition, the importance of saliva in digestion also lies in moistening food and gluing its particles, which facilitates chewing, bolus formation and swallowing. For the normal functioning of saliva components, an alkaline environment (pH > 7.0) is required.

Language- This is a muscular organ attached at the posterior end. It provides the perception of taste, temperature and texture of food, and also facilitates the mixing of food in the mouth and swallowing of the food bolus. The contact of a bolus of food on the root of the tongue stimulates the swallowing reflex and the movement of food through the pharynx and esophagus into the stomach. At the same time, the epiglottis should close so that it does not end up in the respiratory tract. The tongue, together with the teeth, is involved in the formation of articulate speech (Fig. 5.9).

The tonsils, which perform a protective function, are also located deep in the oral cavity.

Thus, grinding, wetting and primary digestion of food, as well as the perception of its taste, occur in the oral cavity.

Pharynx is part of the digestive tube connecting the oral and nasal cavities on one side, and the esophagus with the larynx on the other.

Esophagus- This is a muscular tube lined with epithelium from the inside through which food enters the stomach. The length of the esophagus is about 23-25 ​​cm. It begins in the cervical region, passes through the chest cavity, the diaphragm and flows into the stomach, which lies in the abdominal cavity. The esophagus is located behind the trachea.

All organs of the digestive system located in the abdominal cavity - the stomach, small and large intestines - are not scattered there randomly, but are suspended on mesenteries - cords of connective tissue.

Stomach- a hollow muscular organ with a volume of 1.5-2 liters. The walls of the stomach are lined with epithelium, which secretes gastric juice and mucus, which prevents digestion of the stomach walls (Fig. 5.10).

Gastric juice contains the enzyme pepsin and hydrochloric acid. Hydrochloric acid activates pepsin and partially disinfects food, and also makes the environment in the stomach acidic (pH< 7,0). Под действием пепсина происходит расщепление бел­ков до аминокислот. Сокращение стенок желудка обеспечивает перемешивание пищи и ее продвижение в направлении кишечни­ка. В желудке пища задерживается от 2 до 48 часов в зависимости от ее химической природы.

At the border of the stomach and small intestine there is a sphincter - a circular muscle that does not allow food to return back if it has entered the intestines.

The human intestine is divided into thin and thick. Length small intestine is about 5-6 m, it is formed by the duodenum, jejunum and ileum. The ducts of the liver and pancreas open into the duodenum.

The walls of the small intestine are covered with numerous epithelial outgrowths - villi, and also contain numerous intestinal glands that produce intestinal juice. In the small intestine, under the influence of enzymes from the pancreatic juice and intestinal juice secreted by the glandular cells of the walls, the final breakdown of carbohydrates, proteins and fats occurs, as well as their absorption into the blood and lymph. For normal functioning of enzymes in the small intestine, an alkaline environment (pH > 7.0) is optimal. The walls of the intestinal villi have microvilli, which contributes to a significant increase in the absorption surface of dissolved substances, which enter the blood and lymphatic capillaries that penetrate the villi from the inside, and are then distributed throughout the body (Fig. 5.11).

It should be noted that carbohydrates and amino acids are absorbed into the blood and necessarily pass through the liver, while products of the breakdown of fats entering the lymph bypass the liver.

IN large intestine, formed by the cecum, colon and rectum, the breakdown of substances is completed, water is reabsorbed and feces are formed (Fig. 5.12).

It also contains symbiotic bacteria that break down some substances undigested by the human body, such as cellulose, synthesizing vitamins (for example, group B) and other biologically active substances, which are then absorbed into the blood and used by the body. Feces are periodically removed from the body through bowel movements.

The cecum has a vermiform appendix, which is an organ of the immune system. Its inflammation is called appendicitis.

Liver is the largest gland in the body, weighing about 1.5 kg (Fig. 5.13).

It ensures the neutralization of toxic substances that enter the blood, promotes the digestion of food, and also performs a storage function. The secretion of the liver is called bile, it promotes emulsification, saponification, breakdown and absorption of fats, and also stimulates contractions of the intestinal walls. Emulsification is the breaking up of large fat droplets into smaller ones, which makes them easier for enzymes to access. The breakdown products of substances harmful to the body are also released with bile. About 1.5-2 liters of bile are produced per day, but some of it temporarily accumulates in the gallbladder in the absence of food. The blood vessels that line the walls of the small intestine collect in the portal vein of the liver. The blood brought by the portal vein undergoes a kind of purification, during which substances toxic to the body are neutralized. Excess glucose in the blood plasma is retained in the liver and stored as glycogen, released when necessary. This process is regulated by pancreatic hormones - insulin and glucagon.

Pancreas(Fig. 5.13) refers to the glands of mixed secretion, since part of its cells secrete digestive juice into the small intestine, and the other part releases the hormones insulin and glucagon into the bloodstream. Pancreatic juice contains enzymes that break down carbohydrates, proteins and fats, such as amylase, trypsin and lipase.

The great Russian physiologist studied the processes of digestion and their reflex nature

I. P. Pavlov. In experiments on dogs, he proved that the production of saliva and gastric juice is an unconditioned reflex to the smell and sight of food.

The structure and vital functions of the organs of the respiratory system

Breath is one of the most important functions of a living organism, which ensures the release of energy from chemical bonds of organic compounds and the formation of final metabolic products - carbon dioxide and water. If a person can live without food for about 30 days, without water - 10, then without air - up to 6 minutes, after which irreversible changes occur in the brain. In the human body and a number of animals, respiration is a multi-stage process, during which air enters the lungs, then its oxygen diffuses into the blood, is transported from it to tissues, penetrates into cells, where, finally, the process of releasing energy directly occurs, called tissue respiration.

External respiration, or the process of gas exchange between the body and the environment, depends entirely on the functioning of the respiratory system. In addition, it plays an important role in thermoregulation, excretory and speech functions. Thus, maintaining a constant body temperature is associated with the formation of water vapor, the separation of which leads to cooling of the tissues. You can detect the release of steam even from a sleeping or unconscious person; if you hold a mirror to his lips, it will definitely fog up. When a person enters cold water, he holds his breath to maintain body temperature. Exhaled air, in addition to carbon dioxide and steam, contains ammonia and other volatile metabolic products, and, for example, urea can be released with coughed up mucus. The formation of sounds is also associated with the respiratory system, since it is in it that the vocal cords are located, and some languages ​​even have special nasal sounds (Fig. 5.14).

The structure of the respiratory system. The human respiratory system consists of the respiratory tract (Fig. 5.15) and lungs. The respiratory tract, in turn, is divided into the nasal cavity, nasopharynx, larynx, trachea and bronchi, which branch in the lungs into numerous tubules - bronchioles.

Nasal cavity opens outward with the nostrils on one side and communicates with the nasopharynx on the other. It is divided by the nasal septum into two symmetrical halves - right and left, each of which is divided into nasal turbinates and passages. The nasal cavity is lined with ciliated epithelium with numerous glandular cells and is abundantly supplied with blood. In it, the air is cleaned of suspended particles, including pathogens of various diseases, moistened and brought to body temperature (warmed or cooled). In the upper part of the nasal cavity there are olfactory receptors that provide the perception of smell. The nasal cavity communicates with the paranasal sinuses, for example the maxillary sinus, which are involved in warming the air and are sound resonators, and with the nasolacrimal duct, through which part of the tear fluid flows.

Nasopharynx It communicates not only with the nasal cavity, but also with the oral cavity, through which air enters the larynx.

Larynx- a funnel-shaped connective tissue organ covered by a cartilaginous epiglottis. When food hits the root of the tongue, when the reflex act of swallowing occurs, the epiglottis must close to prevent food from entering the respiratory tract.

The anterior part of the larynx is formed by the thyroid cartilage, which in men fuses at an acute angle and forms Adam's apple, or Adam's apple. The vocal cords are located in the larynx, which, together with the teeth, tongue and lips, provide articulate speech. Men have longer vocal cords than women, as a result of which the timbre of their voice is usually lower.

Trachea it is protected in front by cartilaginous half-rings, and in the back it is covered with an elastic connective tissue septum, which ensures the unhindered passage of food through the esophagus, located directly behind the trachea. In the lower part, the trachea branches into two bronchi - right and left.

Bronchi formed by cartilaginous rings. Entering the lungs, they begin to branch into smaller and smaller bronchi of the following orders and bronchioles, ending in vesicles - alveoli, collected in cluster-shaped structures.

Lungs- paired organs lying in the thoracic cavity, limited by the rib cage and diaphragm. Below the left lung is the heart, so the left lung is smaller than the right. The human lungs have an alveolar structure (Fig. 5.16). The walls of the alveoli are lined with epithelium and densely braided with capillaries; they secrete a special liquid that promotes gas exchange and prevents the walls of the alveoli from collapsing. In the alveoli, the air gives oxygen to the blood and is enriched with carbon dioxide.

The lungs are covered with pleura, which has two layers - outer and inner, between which there is pleural fluid, which reduces the friction force during respiratory movements.

The mechanism of pulmonary ventilation. During breathing, inhalation occurs in the following sequence: the intercostal muscles contract, the ribs rise, the diaphragm lowers, the volume of the chest increases, the pressure in the chest cavity drops, which leads to stretching of the lungs and drawing air into them. Exhalation occurs in the reverse order: the intercostal muscles and diaphragm relax, the ribs descend, the diaphragm rises, the volume of the chest decreases, the volume of the lungs contracts and air is pushed out.

Gas exchange in tissues. By inhaling and exhaling, a person ventilates the lungs, maintaining a relatively constant composition of gases in the alveoli. In the inhaled air the oxygen concentration is increased, and in the exhaled air it is reduced. The content of carbon dioxide in exhaled air, on the contrary, is higher than in inhaled air.

The composition of alveolar air differs from both inhaled and exhaled air, which is explained by the mixing of air entering or leaving the lungs with air contained in the respiratory tract itself.

In the lungs, oxygen from the alveolar air passes into the blood, and carbon dioxide from the blood into the lungs by diffusion through the walls of the alveoli and blood capillaries. The direction and speed of diffusion are determined by the partial pressure of the gas in the air, or its tension in the solution. The partial pressure of a gas is the part of the total pressure of gases that is determined by a given gas. The difference between the tension of gases in the venous blood and their partial pressure in the alveolar air is about 70 mm Hg for oxygen. Art., and for carbon dioxide - 7 mm Hg. Art. This difference allows you to meet the body's needs even during physical work and sports.

Blood transports oxygen from the lungs to the tissues and carbon dioxide from the tissues to the lungs in a state bound to the hemoglobin of red blood cells.

Oxygen-enriched blood enters all organs and tissues of the body, where oxygen diffusion occurs in the tissue, which is caused by the difference in voltage in the blood and tissues. In cells, oxygen is used in the biochemical processes of tissue respiration - the oxidation of organic compounds to carbon dioxide and water with the formation of ATP.

Respiratory and pulmonary volumes. Ventilation of the lungs is determined by the depth of breathing (tidal volume) and the frequency of respiratory movements. To study breathing characteristics, special instruments are used - spirographs, spirometers, etc.

The depth of breathing and its frequency depend on physical activity, degree of fitness, emotional state, environmental conditions and other reasons. At rest they are small (about 500 ml of air and 12-18 respiratory movements per minute, respectively), while, for example, in the cold, gas exchange increases, thereby maintaining a constant body temperature. In this regard, a number of pulmonary volumes and capacities are distinguished.

1. Tidal volume - the volume of inhaled and exhaled air in a calm state (on average about 500 ml).

2. Inspiratory reserve volume is the additional volume of air that a person can inhale after a normal inhalation (about 1,500 ml).

3. Expiratory reserve volume - the volume of air that a person can still exhale after normal exhalation (about 1,500 ml).

4. Residual lung volume - the volume of air that remains in the lungs after the deepest exhalation (about 1,200 ml).

5. The vital capacity of the lungs is the volume of air that can be exhaled after the deepest breath; is the sum of tidal volume, inspiratory and expiratory reserve volumes (3.5-4.7 l).

6. Total lung capacity - the volume of air contained in the lungs after the deepest inhalation: is the sum of the vital capacity and the residual volume of the lungs (4.7-5 l).

7. Functional residual capacity - the volume of air remaining in the lungs after a quiet exhalation: the sum of the expiratory reserve volume and the residual volume (2.7-2.9 l). Provides equalization of fluctuations in gas concentrations in inhaled and exhaled air. Regulation of breathing. On the one hand, “respiratory” neurons send rhythmic impulses to the intercostal muscles and the diaphragm, and on the other hand, they are sensitive to signals coming from a variety of receptors. Some receptors are located in the lungs and respiratory tract and respond to stretching. Other receptors are located in the medulla oblongata and the walls of blood vessels and respond to changes in the concentration of carbon dioxide, oxygen, and blood pH. Inhalation is caused by an increase in the concentration of carbon dioxide in the blood, and exhalation is stimulated by the stretching of the walls of the airways and lungs. Despite the fact that the respiratory center is located in the medulla oblongata, “respiratory” neurons are also located in higher parts of the nervous system. In general, breathing is a reflex act.

The intensity of breathing can be significantly influenced by the higher respiratory centers in the cerebral cortex of the forebrain, as well as the autonomic nervous system. Thus, its sympathetic department contributes to increased breathing and an increase in the depth of breathing, while the parasympathetic department, on the contrary, reduces its frequency and depth.

The humoral regulation of respiration mainly involves the adrenal hormone - adrenaline, an increase in the concentration of which helps to increase the frequency and strength of respiratory movements.

Diseases of the respiratory system. Since the respiratory system is directly connected with the environment, pathogens of numerous diseases penetrate into it. The most common diseases are runny nose, sinusitis, pharyngitis, tracheitis, bronchitis, pneumonia and tuberculosis. Some are caused by viruses, while others, such as pneumonia and tuberculosis, are caused by bacteria. Recently, the incidence of tuberculosis has become epidemic.

The structure and functioning of the organs of the excretory system

In the human body, excretion is carried out using the excretory, digestive, respiratory systems, sweat and sebaceous glands of the skin. However, the leading role in this life process is played by the excretory system.

The structure of the excretory system. The excretory system includes the kidneys, ureters, bladder and urethra. The kidneys are paired bean-shaped organs located in the lumbar region of the abdominal cavity on the dorsal side. On the inner concave surface of the kidney there is a gate through which arteries and nerves enter and veins, lymphatic vessels and the ureter exit (Fig. 5.17). The functions of the kidneys are the removal of metabolic end products in the process of urine formation, maintaining water-salt balance, regulating blood pressure, etc.

In a cross section of the kidney, the cortex and medulla, as well as the renal calyces and the renal pelvis are distinguished. The functional unit of the kidney is the nephron. Each kidney contains up to 1 million nephrons. Nephron consists of a Shumlyansky-Bowman capsule, enclosing a glomerulus of capillaries, and tubules connected by the loop of Henle. The nephron capsules and part of the tubules are located in the cortex, while the loop of Henle and the remaining tubules pass into the medulla. The nephron is abundantly supplied with blood: the afferent arteriole forms a ball of capillaries in the capsule, they gather into the efferent arteriole, which again breaks up into a network of capillaries that intertwine the tubules and only then gather into a vein (Fig. 5.18).

Urine formation. The process of urine formation consists of three stages: glomerular filtration, tubular reabsorption and secretion. In progress filtering Due to the pressure difference, water and most of the low molecular weight substances dissolved in it - mineral salts, glucose, amino acids, urea, etc. - leak from the blood into the capsule cavity due to the pressure difference. The result of filtration is the formation of weakly concentrated primary urine. Since blood passes through the kidneys many times, a person produces 150-180 liters of primary urine during the day.

Metabolic end products, such as urea and ammonia, as well as a number of ions and antibiotics, can be additionally released into the urine by cells in the tubular walls - a process called secretion.

Immediately after filtration the process begins reabsorption- reabsorption of water and part of the substances dissolved in it, in particular glucose, amino acids, vitamins and many ions. As a result of reabsorption, 1-1.5 liters of secondary urine per day are formed, which should not contain either glucose or proteins. It mainly contains breakdown products of nitrogenous compounds - urea and ammonia, which are toxic to the body.

Urination. The nephron tubules carry urine into the collecting ducts, and from there into the renal calyces and renal pelvis. From the renal pelvis, urine is collected through the ureters into the bladder - a hollow muscular organ that holds up to 0.5 liters of liquid. Urine is periodically removed from the bladder through the urethra.

Regulation of urination and urination. Urination is a reflex act. The urination center is located in the sacral part of the spinal cord. The unconditioned stimuli are not the pressure of urine in the bladder, but the stretching of its walls and the rate of filling.

To a large extent, urinary processes are regulated humorally: antidiuretic hormone (vasopressin) of the pituitary gland and aldosterone of the adrenal cortex enhance reabsorption.

Diseases of the excretory system. If personal hygiene rules are violated, there is a serious risk of various inflammatory diseases. They can also be provoked by diseases of other organs and the use of antibiotics. The most common diseases of the excretory system are urethritis (inflammation of the urethra), cystitis (inflammation of the bladder) and some forms of nephritis.