Osmotic call the phenomena occurring in a system consisting of two solutions separated by a semi-permeable membrane. In a plant cell, the role of semi-permeable films is performed by the boundary layers of the cytoplasm: plasmalemma and tonoplast.
Plasmalemma- the outer membrane of the cytoplasm adjacent to the cell membrane. Tonoplast- inner cytoplasmic membrane surrounding the vacuole. Vacuoles are cavities in the cytoplasm filled with cell sap- an aqueous solution of carbohydrates, organic acids, salts, low molecular weight proteins, pigments.
The concentration of substances in cell sap and in the external environment (soil, water bodies) are usually not the same. If the intracellular concentration of substances is higher than in the external environment, water from the environment will enter the cell, more precisely into the vacuole, at a faster rate than in the opposite direction. With an increase in the volume of cell sap, due to the entry of water into the cell, its pressure on the cytoplasm, which fits tightly to the membrane, increases. When a cell is completely saturated with water, it has its maximum volume. The state of internal tension of the cell, due to the high water content and the developing pressure of the cell contents on its membrane, is called turgor Turgor ensures that organs retain their shape (for example, leaves, non-lignified stems) and position in space, as well as their resistance to the action of mechanical factors. Loss of water is associated with a decrease in turgor and wilting.
If the cell is in hypertonic solution, the concentration of which is greater than the concentration of cell sap, then the rate of diffusion of water from the cell sap will exceed the rate of diffusion of water into the cell from the surrounding solution. Due to the release of water from the cell, the volume of cell sap is reduced and turgor decreases. A decrease in the volume of the cell vacuole is accompanied by the separation of the cytoplasm from the membrane - occurs plasmolysis.
During plasmolysis, the shape of the plasmolyzed protoplast changes. Initially, the protoplast lags behind the cell wall only in certain places, most often in the corners. Plasmolysis of this form is called corner(Fig. 1, B).
Then the protoplast continues to lag behind the cell walls, maintaining contact with them in certain places; the surface of the protoplast between these points has a concave shape. At this stage plasmolysis is called concave(Fig. 1, B).
Gradually, the protoplast breaks away from the cell walls over the entire surface and takes on a rounded shape. This plasmolysis is called convex.
If the protoplast retains its connection with the cell wall in certain places, then with a further decrease in volume during plasmolysis, the protoplast acquires an irregular shape. The protoplast remains connected to the shell by numerous Hecht's threads. This plasmolysis is called convulsive.
If a plasmolyzed cell is placed in hypotonic solution, the concentration of which is less than the concentration of cell sap, water from the surrounding solution will enter the vacuole. As a result of an increase in the volume of the vacuole, the pressure of the cell sap on the cytoplasm will increase, which begins to approach the cell walls until it takes its original position - it will happen deplasmolysis.
Osmosis. plays an important role both in the entry of gases and liquids into the plant and in their release - for example. during the absorption of soil solutions by roots, during the exchange of gases by leaves, etc. Likewise, oxygen is essential during the movement of nutrients within a plant from cell to cell. Osmotic movements are generally determined by the properties of cell membranes and mainly the peripheral (leathery) layer of protoplasm. The osmotic pressure exerted by the cell sap on this layer of protoplasm and on the membrane is usually quite significant; it is called cell turgor and is one of the necessary conditions for cell growth. Exosmosis weakens or completely destroys turgor, as a result of which the cell. Sucking force- the amount of excess of osmotic pressure inside the cell over the turgor pressure of the tense cell membrane. The greater the difference between them, the greater the suction force, which ensures that nutrients from water or soil solutions enter the cell. Lithophytic algae have the greatest sucking force - more than 150 atm, haloxerophytic subshrubs - up to 100 atm, hydrophytes have the least - 1-5 atm
35..VITAMINS, FAT SOLUBLE. Vitamin A (antixerophthalic).Vitamin D (antirachitic).Vitamin E (vitamin of reproduction).Vitamin K (antihemorrhagic).Vitamin A - retinol. Many people know that the main importance of this vitamin is its benefits for our vision. Also, it is involved in the regulation of hormone levels, affects the condition of the mucous membranes, stimulates regeneration processes in the skin, and ensures the normal functioning of the nervous system. This vitamin is necessary for the beauty and health of women. Vitamins of group D. Ensure healthy teeth, bones, good resistance to diseases, etc. The group includes vitamins D1, D2, D3, D4, D5. Vitamin D3 stands out among them. Vitamin E is tocopherol. It affects tissue regeneration, circulation and blood clotting, protects cells from free radicals, helps the formation of collagen and elastic fibers. This vitamin is considered female. Its special significance for women is to help with premenstrual syndrome. Vitamin K. The main importance of this vitamin is to ensure normal blood clotting. It stimulates the production of prothrombin. This is a group of vitamins that includes several types of vitamin K.
36.cytoplasm, its chemical composition. Cytoplasm is colorless, has a mucous consistency and contains various substances, including high-molecular compounds, for example proteins, the presence of which determines the colloidal properties of the cytoplasm. Cytoplasm is part of the protoplast, enclosed between the plasmalemma and the nucleus. The basis of the cytoplasm is its matrix, or hyaloplasm, a complex colorless, optically transparent colloidal system capable of reversible transitions from sol to gel.
In the cytoplasm of plant cells there are organelles: small bodies that perform special functions - plastids, Golgi complex, endoplasmic reticulum, mitochondria, etc. Most of the processes of cellular metabolism take place in the cytoplasm, excluding the synthesis of nucleic acids that occur in the nucleus. The cytoplasm is penetrated by membranes - the thinnest (4-10 nm) films, built mainly from phospholipids and lipoproteins. Membranes limit the cytoplasm from the cell membrane and vacuole and inside the cytoplasm form the endoplasmic reticulum (reticulum) - a system of small vacuoles and tubules connected to each other.
The most important property of the cytoplasm, associated primarily with the physicochemical properties of the hyaloplasm, is its ability to move. In cells with one large vacuole, movement is usually carried out in one direction (cyclosis) due to special organelles - microfilaments, which are filaments of a special protein - actin. The moving hyaloplasm entrains plastids and mitochondria. Cell sap, located in vacuoles, is an aqueous solution of various substances: proteins, carbohydrates, pigments, organic acids, salts, alkaloids, etc. The concentration of substances found in cell sap is usually higher than the concentration of substances in the external environment (soil, water bodies). The difference in concentrations to a certain extent determines the possibility of water and soil solutions entering the cell, which is to some extent explained by the phenomenon of osmosis. In a cell, the role of a semi-permeable membrane is played by the cytoplasm. The boundary layers of the cytoplasm lining the cell membrane and the cell vacuole are permeable only to water and some solutions, but impermeable to many substances dissolved in water. This property of the cytoplasm is called semi-permeability or selective permeability. Unlike the cytoplasm, the cell membrane is permeable to all solutions; it is impenetrable only to solid particles. The entry of substances into the cell cannot be reduced only to osmotic phenomena, which are expressed in adult cells with well-developed vacuoles. In reality, this is a very complex process due to many factors. The entire system of cytoplasmic colloids takes an active part in the absorption of substances. The intensity of movement depends on temperature, degree of lighting, oxygen supply, etc.
In very young cells, the cytoplasm fills almost the entire cavity. As the cell grows, small vacuoles appear in the cytoplasm filled with cell sap, which is an aqueous solution of various organic substances. Subsequently, with further cell growth, the vacuoles increase in size and, merging, often form one large central vacuole, pushing the cytoplasm towards the cell membrane. In such cells, all organelles are located in a thin wall layer of cytoplasm. Sometimes the nucleus remains in the center of the cell. In this case, the cytoplasm, forming a nuclear pocket around it, is connected to the wall layer by thin cytoplasmic strands.
The cytoplasm layer contains chloroplasts lining the upper wall. They are almost round or slightly oval bodies. Occasionally you can see plastids pulled in the middle.
45. Isoenzymes, or isoenzymes, are isoforms or isotypes of the same enzyme that differ in amino acid sequence, existing in the same organism, but, as a rule, in different cells, tissues or organs. Isoenzymes are usually highly homologous in amino acid sequence and/or similar in spatial configuration. The active centers of isoenzyme molecules are especially conservative in maintaining their structure. All isoenzymes of the same enzyme perform the same catalytic function, but can differ significantly in the degree of catalytic activity, regulatory features, or other properties. An example of an enzyme that has isoenzymes is hexokinase, which has four isotypes, designated by Roman numerals from I to IV. Moreover, one of the isotypes of hexokinase, namely hexokinase IV, is expressed almost exclusively in the liver and has special physiological properties, in particular, its activity is not inhibited by its reaction product glucose-6-phosphate. Another example of an enzyme that has isoenzymes is pancreatic amylase amylase differs in amino acid sequence and properties from the amylase of the salivary glands, intestines and other organs. This served as the basis for the development and application of a more reliable method for diagnosing acute pancreatitis by determining not total plasma amylase, but pancreatic isoamylase. The third example of an enzyme that has isoenzymes is creatine phosphokinase - the isotype of this enzyme expressed in the heart differs in amino acid sequence from creatine phosphokinase skeletal muscles. This makes it possible to differentiate myocardial damage (for example, during myocardial infarction) from other causes of increased CPK activity by determining the myocardial isotype of CPK in the blood
Stressed state of plant cells, tissues and organs due to mutual pressure of cell membranes and their contents. The turgor pressure that occurs during the osmotic flow of water into the cell is always equal to the back pressure of the cell membrane on the protoplast increasing in volume. The relationship between turgor and osmotic pressure is of great importance in the process of water absorption, since in most plants the suction force, that is, the force with which the cell absorbs water, is equal to the difference between osmotic and turgor pressure. However, under certain conditions, the shell not only does not put pressure on the protoplast, but, on the contrary, seems to stretch it. This phenomenon (cytorrhiz) occurs in some plants, especially xerophytes, during periods of severe drought. Thanks to T., plant organs acquire a certain structural strength and elasticity, and leaves and herbaceous stems acquire a vertical or plagiotropic position. Changes in T. are mainly due to nastic movements in plants, the closing and opening of stomata.
- - stressed state of plant cells, tissues and organs due to mutual pressure of cell membranes and their contents...
Dictionary of botanical terms
- - stressed state of the cell wall created by hydrostatic pressure of intracellular fluid. In the T. state, cells are saturated with water...
Anatomy and morphology of plants
- - the stressed state of the cell membrane, depending on the osmotic pressure of the intracellular fluid, the osmotic pressure of the external solution and the elasticity of the cell membrane...
Physical Anthropology. Illustrated explanatory dictionary
- - hydrostatic pressure in plant and bacterial cells; the result of OSMOTIC injection of water. Water penetrates the semi-permeable cell membrane, causing the cell to swell...
Scientific and technical encyclopedic dictionary
- - tension and elasticity of tissue, changing depending on its physiological state...
Large medical dictionary
- - a state of fullness of tissues caused by their swelling...
Medical terms
- - or intracellular pressure - is caused by osmotic processes between the soil solution or water washing the plant cell and the cell sap, which contains a variety of osmotically strong substances, such as...
Encyclopedic Dictionary of Brockhaus and Euphron
- - tense state of cells caused by intracellular hydrostatic pressure. A decrease in turgor is accompanied by the processes of withering, aging and cell destruction...
Modern encyclopedia
- - internal hydrostatic pressure in a living cell, causing tension in the cell membrane...
The main indicators of youth and beauty of female representatives are skin elasticity and firmness. What do experts mean when they talk about dermal turgor? We will cover this issue in as much detail as possible. You will also learn why turgor decreases and how to restore it.
What is skin turgor
Skin turgor (tone) is the internal pressure of cells + tension of cell membranes. It is the tone of the dermis that indicates the ability of the skin to resist mechanical stress (pressure, pulling) and the quality of the water balance.
To check turgor, you can grab a section of the epithelium, hold it for a couple of seconds, and release it. If the dermis straightens out very quickly, then its tone is in good condition. If it takes longer to straighten, then there are some problems.
The following signs indicate weak skin turgor:
- thinning;
- sagging;
- preservation of fingerprints over a long period of time (after pressing, pulling).
Let's check our facial turgor using the video below:
Reasons for its decline
What is the secret of the elasticity of the dermis? A peculiarity of the female body is the nuance that the turgor of the skin is affected by the hormone estrogen. The functionality of specific dermal cells (fibroblasts) depends on this hormone. The work of fibroblasts is represented by the production of the following substances important for the elasticity of the epithelium:
- collagen;
- hyaluron;
- elastin.
Thanks to these components, the epidermis has a healthy appearance, is dense, and contains a sufficient level of moisture.
The main reason for the decrease in turgor is dehydration of the body and dermis. It is the skin that can lose approximately 0.5 liters of water per day. Due to loss of moisture, the skin needs constant hydration.
Hyaluronic acid helps retain water inside the skin. This substance is a natural component of the epidermis and is necessary for the process of regeneration of dermal cells. Tissue resistance to compression is provided by the binding of water within the intercellular spaces. We also note other important functions of hyaluronic acid:
- stimulation of collagen synthesis;
- transportation of water through skin tissues;
- distribution of water within the dermal tissues.
The body can lose hyaluronic acid for various reasons:
- Poor water quality.
- Excessive exposure to ultraviolet light does not affect the epithelium.
- Frequent use of preservatives.
- Environmental pollution.
Let us indicate other reasons for the decrease in epidermal turgor:
- Intoxication of the body.
- Insufficient hydration, inability to retain moisture within cells, reduced hydration.
- Chronic lack of sleep, stress.
- Oxygen starvation.
- Overstrain in the physical and emotional sphere.
- Bad habits.
- Constant dysbacteriosis.
- Diseases of internal organs.
Checking your turgor
How to increase or restore turgor
Hyaluronic acid is produced by the body in smaller quantities after age 25. This means that from this age, representatives of the fair sex should nourish and moisturize the skin. There are many ways to keep your skin youthful.
- Water procedures in the form of a contrast shower help increase blood circulation and increase the elasticity of the walls of blood vessels. It is also useful to swim in lakes, rivers, seas, and wash with cold water. Baths with aromatic oils are considered very useful.
- Water is useful not only in the form of procedures, but also for oral administration. Water is considered the most powerful energy-information element. It is important to drink clean water throughout. For every kilogram of weight, the body needs 30 ml of water per day.
- It also needs to be limited without any protection. The epidermis must be protected from direct rays by clothing and creams containing SPF.
- Also, do not forget about a healthy lifestyle. The diet must necessarily contain plant foods.
- You need to monitor the moderation of physical activity and adherence to the daily routine.
- The psycho-emotional state, positive attitude, willingness to help people, etc. are also important.
Vitamin therapy
Special attention should be paid to:
- A (). Its merit is in thickening the stratum corneum. Thanks to it, the moisture content of the epithelium and its elasticity are maintained. It is present in fish oil, egg yolks, animal fats, vegetables, and fruits.
- IN. Vitamins from this group are responsible for metabolic processes within the epidermis. They are also needed for redox processes. Contained in legumes, fish, dairy products, legumes, and cereals.
- E (tocopherol). This “vitamin of youth” is responsible for the integrity of muscle fibers, prevents capillary fragility, and maintains the required level of moisture in the dermis. It contains nuts, avocados, seeds, wheat germ oil, and vegetable oil.
- PP(). It is considered necessary for the redox processes of the body and is responsible for the biochemical balance inside the cells of the epidermis. Present in potatoes, meat, beans, liver, nuts, yeast.
Home treatments
You can maintain the condition of your skin not only by regularly visiting beauty salons, but also at home. Among the methods that effectively increase the tone of the dermis at home, we will indicate:
- Peeling of the face and body through scrub, gommage. Procedures are recommended twice a week. Thanks to the procedures performed, the skin will be cleansed, blood circulation and metabolism within the tissues will be accelerated.
- Using scrubs. Coffee scrub and sea salt scrub are very effective.
- A contrast shower will help tone the walls of blood vessels, increase blood microcirculation, and increase the elasticity of the epidermis.
- . They help not only to lose weight. One of the beneficial effects of the wrap is improving the condition of the epidermis and increasing its tone. A bathhouse has a similar effect.
- Baths with aroma oils.
- Mimic exercises.
Exercises
To improve blood supply to the dermis, activate the regeneration process, and improve lymph outflow, exercises for the facial muscles are necessary. Additionally, you will be surprised to know that Kegel exercise helps restore skin turgor. Every day you should perform rhythmic contractions of the intimate muscles for 10 minutes. This exercise increases blood supply to the pelvic organs and activates the production of estrogen, which is responsible for the normal tone of the epidermis.
Massage
Oils
Preference should be given to the following oils: mint, pine, rose, myrrh, frankincense, nutmeg, sandalwood. To prepare a bath, 5–7 drops of ether are enough. Baths are taken twice a week for 10-15 minutes.
Masks
It is useful to apply masks. Masks based on the following substances will help increase the turgor of the epidermis: collagen, hyaluronic acid, vitamins A, E, coenzyme Q10, elastin.
Masks for facial skin elasticity are described in this video:
Drugs
Cosmetologists are constantly developing new products (creams, lotions, masks) for skin care.
- One of the care products that has a light texture and high efficiency is the Cellular Body Firming Mousse (manufactured in Switzerland by Skincode). This product provides a bright lifting effect and returns its elasticity to the epidermis.
- Slim Shape+ (produced by Estee Lauder) will help tighten and make the skin smooth.
- One of the effective anti-aging facial products is the modeling gel “HydroForm Contouring Gel” (manufactured by “Darphin”). It will help restore elasticity to the dermis, strengthen the contour of the body, soften the epidermis, and reduce visibility. The product is made on the basis of aromatic oils.
Treatment without surgery
Physiotherapeutic procedures are considered especially useful for increasing turgor. They improve blood microcirculation, preserve youth, and increase the elasticity of capillary walls. The most common physiotherapy procedures are:
- . Under the influence of ozone, the epithelium is smoothed and turgor improves.
- . The procedures involve injecting drugs into the tissues of problem areas. The specialist determines the composition of the drug individually (antioxidants, vitamins, amino acids, microelements.
- . Injections with thin needles are painless and help smooth the epidermis.
- . The hardware method of tightening involves exposing the dermis to special radiation that stimulates the synthesis of melanin and collagen.
- . Microcurrent pulses with low frequency have a gentle effect on the layers of the dermis and fat layer. The procedure activates microcirculation, lymphatic drainage, improves facial contour, and tightens the cheeks.
- RF therapy. The tissue is exposed to radio wave radiation. Under the influence of the waves, the protein compounds of the epidermis are denatured, and the stretching of collagen fibers stops.
It is considered a popular way to increase dermal turgor. This modern rejuvenation procedure consists of introducing a special preparation containing hyaluronic acid and vitamins into the layers of the dermis. Thanks to innovative technology, the skin regains lost tone, color, and elasticity. !
Operation
An effective tightening procedure is contour plastic surgery, which is carried out through intradermal and subcutaneous injections. For injections, preparations with hyaluronic acid (Restylane, Juvederm, Surgiderm) are used. These drugs enhance collagen production and restore water balance. The epidermis after injections is smoothed out and becomes “velvety”.
Platysmoplasty is considered a radical way to increase turgor. The epithelium is tightened through surgery. This method is used when it is pronounced. The operation is carried out in two ways:
- . Small incisions are made in the dermis, the specialist tightens the epidermis, excises excess tissue, and sutures the incision. After the procedure, the stitches are almost invisible.
- Classical. An incision is made along the auricle, it goes to the scalp. The skin and subcutaneous tissues are moved, fixed in the desired position, and excess dermis is eliminated.
It will help to increase the efficiency of the procedure.
How to improve skin turgor, watch the video below:
A living cell is an integral biological system, all parts of which must work together to ensure normal functioning and life as a whole. One of the characteristics that directly affects the viability of a particular plant cell is turgor pressure. There are quite serious differences in structure between plant and animal cells. This is due to the fact that their organisms belong to different kingdoms with different needs and life cycles.
Turgor pressure
This is primarily the ability of the cell not to lose shape due to the pressure of the liquid from the inside on the cell wall. Thanks to a process called osmosis in physics, liquid enters a dry cell through the membranes, which occupies a certain volume, as if pushing the cell’s cytoplasm closer to its outer shell. Such liquid pressure is also necessary in order to regulate the process of further fluid supply: when the cell is completely filled, osmosis stops.
It should be separately explained that animal cells, due to the absence of vacuoles and cell sap, have minimal turgor pressure. Therefore, further information will concern only plant cells - the turgor in them is very significant.
Osmotic pressure
Osmotic and turgor pressure should not be confused, despite the fact that the processes described are similar. In fact, osmotic pressure is an integral part of turgor: external and internal osmosis, combined with the level of elasticity of the cell wall, ensures the balance of internal fluid pressure in the cell. Thus, when the liquid threshold in the cell is reached, internal osmotic pressure begins to prevent the flow of new solution. And if the level of internal osmotic pressure drops, then with the help of external osmotic pressure the fluid begins to flow into the cell again.
Organoids
What organelles are involved in creating turgor pressure? All parts that make up the cell are combined into a single system. Therefore, one way or another, everyone participates in supporting turgor pressure. However, the vacuole, without a doubt, has the greatest influence on the creation of turgor pressure and its maintenance. It is this that contains reserves of cell sap, which is also necessary to maintain turgor.
After the vacuole, the next extremely important organelle for turgor pressure is the cell wall. It is semi-permeable and allows only strictly defined substances dissolved in the liquid to pass through, retaining unwanted ones. Also, its elasticity directly affects how the cell maintains its shape. If the cell wall is damaged, excess fluid pressure on it may cause the cell to collapse.
Turgor functions
In addition to the fairly obvious function of maintaining cell shape, turgor pressure also has a direct effect on all physiological processes of the cell. It regulates water metabolism, allows you to maintain a balance of general pressure in the cell, and participates in the nutrition process. But since the cell is an integral system, it would not be a mistake to say that this pressure literally affects the entire life activity of both an individual cell and the whole plant.
Also, some of the plant organs (mainly those that provide it with nutrition: etc.) directly depend on the regulation of turgor pressure. It is this that determines the ability of the root to absorb nutrients from the environment. And, as a result, provide the plant with life itself. The balance of intracellular pressure allows the plant to receive exactly as much nutrients as it needs. No more and no less.
Regulating pressure in a plant cell
As noted above, turgor is regulated by the difference between the internal pressure of the liquid and the substances dissolved in it and the external pressure of the environment. With a significant drop in internal pressure, the cell begins to let in liquid and tries to replenish its reserves of cell juice as quickly as possible.
But there is one caveat. If the amount of liquid substance inside has become significant, and it has begun to exert increased pressure on the outer wall of the cell, then the supply of new supplies temporarily stops and is resumed only when the internal pressure drops again. Thus, the content in the cell of both the liquid itself and the substances dissolved in it is regulated.
However, in addition to pressure balance, turgor can also be influenced by the cell membrane. How? A change in its permeability and elasticity can change both the filling of cell sap with certain substances and the very level of pressure that the cell can withstand.
The fact that without turgor plants would be incapable of existence is obvious. Such a simple, but at the same time important process as the flow and flow of fluid in a cell affects the entire life of a living organism and requires control, for which specialized organelles such as the vacuole were created.
