Reabsorption and secretion of protein, sodium and chloride in the nitric tubules. Reabsorption - what is it? How is this process implemented and what does it represent? Reabsorption of water in water

The main function of the plant is the processing and removal from the body of waste products, toxic and medicinal substances.

The normal functioning of the nerves corresponds to the normalization of arterial pressure, the process of homeostasis, and the release of the hormone erythropoietin.

As a result of the normal functioning of the nitric system, a cut is established. The mechanism of secretion consists of three mutually related stages: filtration, reabsorption, secretion. The appearance of malfunctions in the organ can lead to the development of undesirable effects.

Zagalni understand

Reabsorption is the process of elimination by the body from the sechovod rivers of different routes.

The process of reversal depletion of chemical elements occurs through narcotic channels with the participation of epithelial cells. The function of the absorbent is unknown. There is a division of elements found in filtration products.

Water, glucose, sodium, amino acids and other ions that are transported into the circulatory system are also absorbed. Chemical deposits, such as decomposition products, exist in excess in the body and are filtered by these cells.

The moisturizing process takes place at the proximal tubules. Then the mechanism of filtration of chemical compounds passes to the loop of Henle, distal convoluted tubules, and collecting tubules.

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Mechanics of processes

At the reabsorption stage, the maximum removal of chemical elements and ions necessary for the normal functioning of the body is achieved. There are several methods for claying organic components.

1. Active. The transport of substances occurs against an electrochemical, concentration gradient: glucose, sodium, potassium, magnesium, amino acids.
2. Passive. Characterized by the transfer of necessary components behind a concentrated, osmotic, electrochemical gradient: water, soda, bicarbonate.
3. Transport with the help of pinocytosis: protein.

Fluidity and filtration rate, transportation of necessary chemical elements and components depend on the nature of the hedgehog, way of life, chronic illness.

Types of reabsorption

Close to the area of ​​the tubules through which the distribution of living elements is obtained, a number of types of reabsorption are seen:

• proximal;
• distal.

Proximally, these channels are visible and transfer from the primary section amino acids, protein, dextrose, vitamins, water, sodium ions, calcium, chlorine, microelements.

1. The water is conveyed to the passive transport mechanism. The fluidity and liquidity of the process lies in the presence of hydrochloride and hydrochloride filtration products.
2. The movement of bicarbonate occurs through an additional active and passive mechanism. The liquid absorbed lies in the area of ​​the organ through which the initial cut will take place. Their passage through the tubules increases in dynamism. The absorption of components through the membrane will require a long time. The passive transport mechanism is characterized by a change in the flow rate, an increased concentration of bicarbonate.
3. Transport of amino acids and dextrose occurs through the epithelial tissue. The stench is located in the brush area of ​​the apical membrane. The process of claying these components is characterized by one-hour dissolution of hydrochloride. Whose concentration of bicarbonate is low.
4. The amount of glucose seen is reduced by maximum connections with the cells that are transported. At high concentrations of glucose, the pressure on transport cells increases. As a result, glucose does not move to the circulatory system.

With the proximal mechanism, maximum protein and peptide degradation is avoided.

Distal reabsorption contributes to the end storage, the concentration of organic components in the secular substance. When doing distal claying, beware of actively soaking up the meadow. Potassium, calcium ions, phosphates, and chloride are transported passively.

The concentration of the cut, the activation of moisturizing is determined by the peculiarities of the chemical system.

Possible problems

Dysfunctions of the filtering organ can lead to the development of various pathologies and damage. The main pathologies include:

1. Disorders of tubular reabsorption are characterized by increased and decreased absorption of water, ions, and organic components from the lumen of the tubules. Dysfunction results from decreased activity of transport enzymes, lack of transporters, macroergics, and trauma to the epithelium.
2. Disruption of excretion, secretion by epithelial cells of nitric channels of potassium ions, water, metabolic products: paraaminohyppuric acid, diodrast, penicillin, ammonia. Dysfunctions result from injury to the distal parts of the nephron tubules, damage to the cells and tissues of the cortical and medullary organs. These dysfunctions lead to the development of anxiety and post-anxiety syndromes.
3. Nervous syndromes are caused by the development of diuresis, an alteration in the rhythm of secretion, a change in the chemical composition and the ingestion of the sechoic substance. Dysfunctions lead to the development of nitric deficiency, nephritic syndrome, tubulopathy.
4. Polyuria is associated with increased urine output and decreased output. The causes of the pathology are:

• too much heat;
• activation of blood flow through the cervix;
• increased hydrostatic pressure on vessels;
• decrease in oncotic pressure of the circulatory system;
• damage to the colloid-osmotic pressure;
• decreased tubular reabsorption of water and sodium ions

1. Oliguria. With this pathology, a decrease in labor output and an increase in the amount of urine output are avoided. The main reasons for the destruction are:

• shortage of food in the body. It results from increased sweating and diarrhea;
• spasm of arterioles, no matter what to bring. The main sign of damage is a bump;
• arterial hypotension;
• blockage, traumatization of capillaries;
• activation of the process of transport of water and sodium ions in the distal tubules.

1. Hormonal imbalances. Activation of aldosterone metabolism leads to increased absorption of sodium in the circulatory system. As a result, there is a risk of excess consumption, which can lead to swelling and a decrease in the concentration of potassium in the body.
2. Pathological changes in epithelial cells Odor is the main cause of dysfunction in sebum concentration control.

The cause of the pathology can be determined using additional laboratory tests.

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The normal functioning of tissues allows for the rapid removal from the body of chemical breakdown products, the exchange of substances, and toxic elements.

In case of signs of disruption of the normal functioning of the organ, it is necessary to consult a doctor. Untimely bathing and lack of daily activity can lead to the development of deformity and chronic illness.

Circulation in the human body has a number of functions: the regulation of blood volume and interclinary circulation, the removal of waste products, the stabilization of acid-salt balance, and the regulation of water-salt. ova rіvnovagi too. All these tasks are subject to complete investigation. Tubular reabsorption is one of the stages of this process.

Tubular reabsorption

Up to 180 liters of primary strength are passed through for each extraction. This liquid is not excreted from the body: so the filtrate passes through the channels, where practically all the liquid is absorbed, and the substances necessary for life - amino acids, microelements, vitamins, which circulate to the blood i. The products of disintegration and exchange are seen in the secondary section. The volume is much smaller - about 1.5 liters per cup.

The effectiveness of nitric acid as an organ largely depends on the effectiveness of tubular reabsorption. In order to understand the mechanism of the process, it is necessary to go back to the boda-nirka unit.

Budova to nephron

The “robotic” claw of the nirk is formed from the advancing parts.

• The corpuscle is a glomerular capsule, with expanded capillaries in the middle.
• Proximal convoluted tubule.
• Loop of Henle - consists of a descending and ascending part. The tonka is expanded in the cerebellum, bent at 180 degrees in order to rise into the cerebellum to the level of the glomerulus. This part forms the original thin and thick part.
• Distal convoluted canaliculus.
• The end tube is a short fragment connected to the collection tube.
• The collecting tube is located in the cerebral ventricle, bringing the secondary sample into the cerebral ball.

The basic principle of placement is as follows: the glomeruli, proximal and distal tubules are located at the medullary ventricle, and the inferior and superior parts and collection tubes are located at the medullary ventricle. The internal cerebral cord loses thin tubes and collecting tubes.
On the video of Budova Nephron:

Mechanism of reabsorption

For effective tubular reabsorption, molecular mechanisms are involved, similar to the movement of molecules through plasma membranes: diffusion, endocytosis, passive and active transport, etc. The most important is active and passive transport.

Active – carried out against an electrochemical gradient. For its implementation, energy and special transport systems are required.

Consider 2 types of active transport:

• Primary active – the energy that is seen when adenosine triphosphoric acid is broken down is released. In this manner, they move, for example, sodium, calcium, potassium, water.
• Secondarily active - energy is not wasted on transferred energy. The main effect is the difference in the sodium concentration in the cytoplasm and the lumen of the tubule. The transporter contains sodium ion. In this way, glucose and amino acids pass through the membrane. The difference in the amount of sodium - less in the cytoplasm, lower level, is explained by the amount of sodium excreted in the intercellular region due to the participation of ATP.

After the membrane is hemmed, the complex splits into a carrier - a special protein, sodium ion and glucose. The carrier rotates to the plate, ready to accept the advancing ion to the metal. Glucose from the interclinary area travels to the capillary and enters the bloodstream. Glucose is only reabsorbed in the proximal part, as long as the necessary carrier is formed here.

Amino acids are absorbed according to a similar pattern. And the process of protein reabsorption is complex: the protein is degraded by pinocytosis - stored in the middle of the cell surface, in the cell it breaks down into amino acids, and then proceeds to the intercellular region.

Passive transport - absorption is carried out along an electrochemical gradient and does not require support: for example, absorption of chlorine ions in the distal canal. It is possible to move along concentration, electrochemical, and osmotic gradients.

In fact, reabsorption is carried out according to schemes that include different methods of transportation. Moreover, when left in the area of ​​the nephron, speech can be absorbed in different ways or not at all.

For example, water is absorbed into any part of the nephron, or by various methods:

• about 40–45% of the water is absorbed in the proximal tubules through the osmotic mechanism - behind ions;
• 25-28% of the water is deposited in the loop of Henle behind the rotary countercurrent mechanism;
• in the distal sinuous tubules up to 25% of water becomes clayey. Moreover, since in the two front sections the water purification is carried out independently of the water supply, the distal process is regulated: the water can be removed from the secondary section or drained away.

The consumption of the secondary section reaches only 1% of the primary consumption.
Video of the reabsorption process:

Rukh speech, scho reabsorbed

There are 2 methods of moving reabsorbed into the interstitial area:

• paracelurium - the transition is carried out through one membrane between two tightly connected cells. This, for example, is diffusion, or transfer from the retailer, or passive transport;
• transcelurium – “through the cell”. The duct contains 2 membranes: luminal or apical, which retains the filtrate in the lumen of the tubule from the cellular cytoplasm, and basolateral, which acts as a barrier between the interstitial medium and cytoplasm Yu. However, one transition is carried out behind the active transport mechanism.

Vidi

In different sections of the nephron, different methods of reabsorption are implemented. Therefore, in practice, the subsection is often discussed based on the characteristics of the robot:

• proximal tubule - called part of the proximal tubule;
• thin – parts of the loop of Henle: thin upstream and downstream;
• distal - the distal convoluted tubule that connects and forms the originating part of the loop of Henle.

Proximal

Here up to 2/3 of the water is absorbed, and glucose, amino acids, proteins, vitamins, and plenty of calcium ions, potassium, sodium, magnesium, and chlorine are released. The proximal tubule is the main supplier of glucose, amino acids and proteins in the blood, so this stage is obligatory and essential.

The reabsorption patterns vary depending on the type of substance that is absorbed.

Glucose in the proximal tubule is absorbed to a greater extent. From the lumen of the tubule into the cytoplasm, it follows through the luminal membrane via countertransport. This is the second active transport that requires energy. The vicor is what is seen when the sodium ion is displaced by an electrochemical gradient. Then glucose passes through the basolateral membrane by diffusion: glucose accumulates in the cell, which ensures a difference in concentration.

Energy is required during the transition across the luminal membrane, transferring energy vitrates across the other membrane. Apparently, the main driver of glucose metabolism is the primary active transport of sodium.

Following the same pattern, amino acids, sulfate, inorganic calcium phosphate, and organic living substances are reabsorbed.

Low-molecular-weight proteins are detected in cells through additional pinocytosis and in cells are broken down into amino acids and dipeptides. This mechanism does not ensure 100% absorption: part of the protein is lost from the blood, and part is removed from the section - up to 20 g per dose.

Weak organic acids and weak bases are reabsorbed through a low level of dissociation by nonionic diffusion. The compounds are disintegrated in the lipid matrix and clayed with a concentration gradient. The soaking should be kept in line with the pH level: with a change, the dissociation of the acid decreases, and the dissociation of the bases advances. At high pH levels, the dissociation of acids increases.

This particularity has been found in the removal of acute speech: when withdrawn, drugs are introduced into the blood that serve to increase the level of acid dissociation and help remove them from the body.

Loop of Henley

Since metals and water are reabsorbed in almost all parts of the proximal tubule, much sodium and chlorine are absorbed in the loop of Henle. The water becomes clayey from 10 to 25%.

The Henley loop implements a rotary-counter-flow mechanism, based on the particularity of the flow of the downstream and upstream parts. The remaining part does not absorb sodium and chlorine, but is no longer permeable to water. The water will soak up the ions, but the water will not penetrate. The result of soaking sodium chloride with the upper part indicates the stage of water purification with the lower part.

The primary filtrate is absorbed from the cob part of the downstream loop, where the osmotic pressure is lower equalized with the pressure of the interclinary part. The cut goes down a loop, releasing water, but saving sodium and chlorine.

As water is removed, the osmotic pressure on the filtrate increases and reaches its maximum value at the turning point. Then the cutting follows the final step, conserving water rather than consuming sodium and chlorine. In the distal tubule, the flow rate is hypoosmotic – up to 100–200 mOsm/l.

Essentially, in the descending branch of the loop of Henle the cross section is concentrated, and in the descending branch it is separated.

On the video of Gentle's loops:

Distal

The distal canaliculus weakly allows water to pass through, and organic fluids are not absorbed here at all. From whom should I stay away from the divorce? In the distal tubule, approximately 15% of the primary fluid is consumed, and approximately 1% is excreted.

As the distal tubule moves, it becomes more and more hyperosmotic, and the fragments here are formed mainly by ions and partly water - no more than 10%. The dilution is carried out at the collecting tubes, where the end section is formed.

A special feature of this robotic segment is the ability to regulate the process of soaking up water and sodium ions. For water, the regulator is antidiuretic hormone, and for sodium, it is aldosterone.

Norm

To assess the functionality of the drug, various parameters are used: biochemical composition of the blood and tissue, the concentration value, as well as partial indicators. The remaining indicators are indicators of tubular reabsorption.

The fluidity of the glomerular filtration indicates the fluidity of the organ, the fluidity of the filtration of the primary section, so as not to remove the protein, through the glomerular filter.

Tubular reabsorption indicates excretory fluidity. Offenses of this magnitude are not constant and change with time.

The norm for FCF is 90–140 ml/min. The highest level during the day decreases until the evening, and the sun is at its lowest level. With physical stress, shock, narcotic or heart failure and other ailments, GFR decreases. May become worse in the early stages of diabetes and hypertension.

Tubular reabsorption does not vary completely, but is determined as the difference between GFR and urine output according to the formula:

P = (GFR - D) x 100 / GFR, de,

• GFR – glomerular filtration rate;
• D – chronic diuresis;
• P – tubular reabsorption.

In case of decreased blood flow - surgery, loss of blood, an increase in tubular reabsorption in the tumor is avoided. Against the background of taking diuretics, in case of various narcotic ailments, it changes.

The norm for tubular reabsorption is 95-99%. There is such a big difference between the volume of the primary section – up to 180 l, and the volume of the secondary – 1–1.5 l.

To determine these values, go to the Rehberg punch. It also helps to calculate clearance - the coefficient of purification of endogenous creatinine. This indicator is used to calculate GFR and the value of tubular reabsorption.

The patient is kept in a supine position for 1 year. Over the course of an hour, the slaughter is collected. The analysis is carried out more carefully.

For pіvgodini from the veins take blood.

Then, the amount of creatinine is determined from the blood sample and the GFR is calculated using the formula:

GFR = M x D/P, de

• M – creatinine level;
• P – rhubarb of speech in plasma
• D – Khvylinny obsyag sechi. To be insured by the division, we will see each other in a timely manner.

Based on the data, you can classify the stage of cleaning:

• A decrease in filtration fluidity to 40 ml/xv is a sign of nitric deficiency.
• A change in GFR to 5-15 ml/min indicates the terminal stage of the disease.
• The change in the Kyrgyz Republic follows after the water supply.
• The increase in blood count is associated with changes in blood volume. The cause may be loss of blood, as well as nephritis - for such ailments the glomerular apparatus is damaged.

Impairment of tubular reabsorption

Regulation of tubular reabsorption

Bleeding in fish is a completely autonomous process. When changing the arterial vice from 90 to 190 mm. rt. Art. The pressure on the nircium capillaries is reduced to a very low level. This stability is explained by the difference in diameter between the blood vessels that bear and bear.

There are two most significant methods: myogenic autoregulation and humoral.

Myogenic – with increased arterial pressure, the walls of the arterioles become shortened, so that less blood flows into the organ and the pressure drops. The sound most often triggers angiotensin II, so thromboxanes and leukotrienes are infused. Vascular dilators are acetylcholine, dopamine and others. As a result, the tension in the glomerular capillaries is normalized in order to maintain a normal level of GFR.

Humoral - for the help of hormones. In fact, the main indicator of tubular reabsorption is the level of soaked water. The process can be divided into 2 stages: obovulcerous - the one that is carried out at the proximal tubules and independent water supply, and the stale stage - carried out at the distal tubules and collecting ducts. This stage is regulated by hormones.

The main one among them is vasopressin, an antidiuretic hormone. The wine saves water and removes moisture from the soil. The hormone is synthesized in the nuclei of the hypothalamus, moves to the neurohypophysis, and is released into the bloodstream. The distal parts have ADH receptors. The interaction of vasopressin with receptors leads to an increase in the permeability of membranes for water, which is why it absorbs faster. In this case, ADH has greater penetration, and it means the level of penetration.

Due to the impact of the pressure on the parenchyma and the distal canal, water from the filtrate is lost in the body. If aphids have low absorption of sodium ions, diuresis may be high.

The absorption of sodium ions is regulated by aldosterone, as well as natriuretic hormone.

Aldesterone stimulates tubular reabsorption of ions and is established when the level of sodium ions in the plasma decreases. The hormone regulates the creation of all mechanisms necessary for the transfer of sodium: the apical membrane channel, the transporter, which establishes the sodium-potassium pump.

There is a particularly strong influx on the collection tubes. The hormone “produces” both in berries and in the vagina, and in the scolio-intestinal tract, which is absorbed by sodium. Aldosterone also regulates the sensitivity of receptors to ADH.

Aldosterone also plays a role for other reasons. With a decrease in arterial pressure, renin is synthesized, which controls the tone of blood vessels. When renin is infused, ag-globulin from the blood is transformed into angiotensin I, and then into angiotensin II. The remaining one is the strongest ship-sounding speech. In addition, it triggers the vibration of aldosterone, which causes the reabsorption of sodium ions, which causes water retention. This mechanism is the silencing of water and blood vessels, creating optimal arterial pressure and normalizing blood flow.

Natriuretic hormone is released in the atrium when it is stretched. Having finished drinking water, the river changes the reabsorption of ions in sodium and water. When the amount of water that is consumed in the second section increases, which changes the underlying blood volume, then the atrium becomes stretched.

In addition, other hormones also flow into the tubular reabsorption:

• parathyroid hormone – coated with calcium supplementation;
• thyrocalciumtonin – reduces the level of reabsorption of this metal ion;
• adrenaline – its infusion should be based on the dose: with a small dose, adrenaline reduces GFR filtration, with a large dose, tubular reabsorption is enhanced;
• thyroxine and somatropic hormone – enhance diuresis;
• Insulin – reduces the absorption of potassium ions.

The mechanism is completely different. Thus, prolactin promotes the penetration of the cell membrane for water, and parathyrin changes the osmotic gradient of the interstitium, thereby influencing the osmotic transport of water.

Tubular reabsorption is a mechanism that accounts for the circulation of water, microelements and living fluids in the blood. There is a reversal of reabsorption, in all sections of the nephron, and in different patterns.

Through the active absorption of most of the osmotically active components, water is reabsorbed through the walls of the canals into the filtrate, which collapses as a result of diffusion. passively.
For a comprehensive characterization of the proportions of different speeches in the nephron, they are composed of the seen speeches that are completely filtered in the glomeruli and are then completely visible from the secondary section.
Clearance is a coefficient of blood purification from various words - a clear understanding of the world. In many cases, the veins are characterized by the volume of blood plasma that can be completely cleansed by liquids of any kind in 1 minute. Clearance is indicated by what is called a “no-threshold” speech, then. speeches that are clearly visible during a one-time passage through the tunnels. Inulin clearance is determined by glomerular filtration and is approximately 120 ml/min. The clearance of paraaminohyppuric acid is determined to assess the effective plasma flow and is currently 600-650 ml/min.
The proximal nephron secretes the most important metabolites, the distal nephron secretes K, H, and NH4 ions.

Impaired protein reabsorption

The glucose that is filtered is practically completely reabsorbed by the cells of the proximal tubules and therefore appears to be present in insignificant amounts. During reabsorption, glucose combines with the carrier (it is phosphorylated) and is transported through the basal part of the cell into the blood. The essential role of sodium ions and the Na pump.
In case of hyperglycemia, which accompanies cerebral diabetes, instead of glucose in the blood, there is a level of “nigar threshold” of 8 mmol/l, a lot of glucose is filtered through the glomeruli, and enzyme systems cannot ensure complete reabsorption Well, glucosuria develops. However, in cases of diabetes, glucosuria may not be associated with abnormalities (angiopathy) and changes in filtration. A slump defect in the enzyme systems of glucose reabsorption manifests itself in the form of a dominantly slumped diabetes mellitus, in which glucosuria develops and normal fatigue leads to a reduced level of blood glucose. Glycosuria may result in permanent damage to the tubular epithelium in ischemia, either when treated with mercury-containing drugs or Lysol.

Impaired protein reabsorption

The protein is reabsorbed in the proximal tubules by pinocytosis, is frequently broken down, and then low-molecular-weight components reach the blood. The mechanisms of protein reabsorption have changed little. Apparently, let's look at the importance of hemodynamics. The appearance of protein in the liver is indicated as proteinuria (albuminuria more often). Hourly low proteinuria up to 1 g/l can be eliminated in healthy individuals after intense physical activity. Proteinuria is a constant sign of illness. Based on the mechanism of development, it is intellectually divided into glomerular and tubular (glomerular and tubular). In case of glomerular proteinuria, due to the increased penetration of the filtering membrane, proteins in large quantities are found in an empty Shumlyansky-Bowman capsule, which outweighs the resorption capacity of the tubular apparatus. When the glomeruli are damaged, mild proteinuria develops. True, the stage of proteinuria does not overcome the severity of illness. Tubular proteinuria is associated with impaired protein reabsorption against the background of damaged tubular epithelium (amyloidosis, sublimate necronephrosis) or with impaired lymphatic drainage. Massive proteinuria occurs in nephrotic syndrome when both glomeruli and tubules are damaged.

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Transport of electrolytes in the nephron

The cells of the proximal nephron reabsorb most of the components of the ultrafiltrate, but during this process the reabsorption of sodium with accompanying anions is necessary. The reabsorption of sodium itself is the function of sodium that is most important for energy consumption. Sodium reabsorption significantly affects the total volume of the section, which is seen to play a role in the regulation of water in the body, osmotic concentration, ion storage of blood and other vital functions. live showmen. For each addition, 1200 g of sodium is filtered, and the result does not exceed 5-10 g. Reabsorption of sodium in different sections of the nephron may vary. Thus, in the proximal segments, where up to 75% of the filtered sodium is reabsorbed, its reabsorption is an active process, but proceeds against a low gradient. Sodium reabsorption in the distal sections operates against a high concentration gradient, which ensures that the visible sections do not displace sodium ions. As established, distal sodium reabsorption is regulated by aldosterone, the adrenal measles hormone. The biochemical mechanisms of active transport of sodium ions are largely unknown. The significance of Mg-deposited ATPase, SDH, and alpha-ketoglutarate dehydrogenase is expected.
Impaired reabsorption of sodium ions can develop if the production of aldosterone is reduced or with the use of inhibitors (osmotic diuretics), or if the sensitivity of the nitric epithelium to aldosterone is reduced. In such sinks, water is lost along with sodium ions with the possible development of dehydration.
The amount of potassium ions seen is about 10% of what is filtered in the glomeruli, and potassium ions are not only reabsorbed, but are often secreted in the distal tubules.

Osmotic dilution and concentration of the section

120 ml of filtrate is reabsorbed in 1 x 119 ml. Up to 85% of the total volume is reabsorbed in the proximal parts of the tubules by osmotically active substances (Na, glucose, etc.), which is referred to as “binding reabsorption” of water. Approximately 15% is reabsorbed in the distal veins and collecting tubes – “facultative reabsorption”.
The level of obstructive reabsorption may change if the reabsorption of sodium or glucose ions is impaired (polyuria in diabetic patients, associated with osmotic diuretics, aldoctan). Facultative reabsorption of water is due to the lack of ADH and the absence of the reaction of the nitric epithelium to the rest (forms of non-urinal diabetes).
Current results show that blood plasma is 4 times hypertonic and 6 times hypotonic with aqueous osmotic concentration ranging from 1002 to 1035. A decrease in the level of concentration of tissue appears as hyposthenuria and isosthenuria.
Signifies external osmotic concentration. The maximum osmotic concentration becomes 270-330 mmol/l (average – 1010-1012).
Additional diuresis in healthy adults is approximately 70% of exogenously administered water. The minimum amount required to remove waste is 500 ml. Polyuria – seen in a volume of more than 2000 ml, oliguria – 400-500 ml, anuria – up to 200 ml.
In the pathogenesis of visual impairment, the state of nervous and humoral regulation is of great importance. Emotional officials can change diuresis, and the activation of the processes of awakening in the measles can lead to polyuria, and galmuvania - coliguria. Polyuria and oliguria can be dismissed as a mental reflex or as a hypnotic inducement.
Often in the minds of pathology, reflex pain anuria is traced. Reflex galvanization of sechovidilennya is possible from different reflexogenic zones. In pathogenesis, the reno-renal reflex is especially important if the injury of another, untreated one, triggers the temporary anuria of another, untreated one. When this occurs, as a result of the activation of the sympathoadrenal system, the tone of the narcotic arterioles increases, which leads to a decrease in glomerular filtration.
Hormonal influxes are significant - thyroxine increases glomerular filtration and, like glucocorticoids, promotes diuresis.

Tubular reabsorption is the process of reabsorption of water and fluids from the tissue, which is located in the lumen of the tubules, lymph and blood.

The bulk of molecules are reabsorbed from the proximal nephron. Here, amino acids, glucose, vitamins, proteins, microelements, a significant number of ions Na+, C1-, HCO3- and many other substances are completely absorbed.

At the loop of Henley, the distal part of the canaliculus and collecting tubes, electrolytes and water are absorbed.

Aldosterone stimulates the reabsorption of Na+ and the excretion of K+ and H+ at the nitric tubule at the distal nephron, at the distal tubule and cortical collecting ducts.

Vasopressin inhibits water reabsorption from the distal convoluted tubules and collecting tubes.

In addition to passive transport, there is the reabsorption of water, chlorine, and waste.

Active transport is the transfer of fluids against electrochemical and concentration gradients. Moreover, primary-active and secondary-active transport are separated. Primary active transport is generated from the wasted energy of the cell. This involves the transfer of Na+ ions to the additional enzyme Na+/K+-ATPase, which generates the energy of ATP. With secondary active transport, the transferred speech acts with additional energy for the transport of another speech. The mechanism of secondary active transport reabsorbs glucose and amino acids.

The magnitude of the maximum tubular transport is consistent with the old concept of the “nircium excretion threshold.” For glucose, the value is set to 10 mmol/l.

Speeches whose reabsorption does not depend on their concentration in the blood plasma are called non-threshold. Before them, there are words that either are not reabsorbed (inulin, manitol) or are little reabsorbed and are visible from the proportional accumulation of them in the blood (sulfate).

Normally, the amount of protein lost in the filtrate is low and is reabsorbed. The process of protein reabsorption occurs through additional pinocytosis. Once infused into protein, the protein undergoes hydrolysis by lysosome enzymes and is converted into amino acids. Not all proteins are amenable to hydrolysis; some of them are converted into blood without changing their appearance. This process is active and requires energy. The appearance of protein in the meat indicates proteinuria. Proteinuria may also occur in physiological individuals, for example, after heavy meat work. Basically, proteinuria occurs in pathology with nephritis, nephropathies, and myeloma.

Sechovin plays an important role in the mechanisms of sequestration concentration and is highly filtered in the glomeruli. At the proximal tubule, part of the sequestration is passively reabsorbed as a result of the concentration gradient that results from the concentration of the separator. Rashta sechovini reach the collection tubes. In the collecting tubes under the infusion of ADH, water reabsorption occurs and the concentration of the substance increases. ADH enhances the penetration of the wall and tissue, and it transforms into the medullary fluid, creating approximately 50% of the osmotic pressure. Through the interstitium along the concentration gradient, the seed diffuses into the loop of Henle and again arrives at the distal canaliculus and collecting ducts. In this way, the internal circle of the family is established. During water diuresis, water is absorbed into the distal part of the nephron, and more fluid is excreted. In this way, the excretion is stored in the diuresis.

Reabsorption of weak acids and bases depends on what form the stench is in - ionized or non-ionized. Weak base acids in the ionized state are not reabsorbed or excreted. The level of ionization of bases increases in an acidic medium, so they are excreted with greater fluidity from the acidic medium, weak acids, however, are more likely to be excreted from the acidic medium. Of great importance are the fragments of many medicinal compounds with weak bases or weak acids. Therefore, when reacting with acetylsalicylic acid or phenobarbital (weak acids), it is necessary to introduce acid solutions (NaHCO3) in order to transfer these acids to the ionization stage, thereby allowing them to be quickly eliminated from the body. For the rapid excretion of weak bases, it is necessary to introduce acidic acidified products into the blood.

Water is reabsorbed from all parts of the nephron passively for the transport of osmotic active substances: glucose, amino acids, proteins, sodium ions, potassium, calcium, chlorine. With decreased reabsorption of osmotically active substances, the reabsorption of water changes. The presence of glucose in the end section leads to increased diuresis (polyuria).

The main ion that ensures passive soaking of water is sodium. Sodium, as it was said, is also necessary for the transport of glucose and amino acids. In addition, it plays an important role in the creation of an osmotically active medium in the interstitium of the globus medullaris, which results in the concentration of the substance.

The supply of sodium from the primary section through the apical membrane in the middle of the tubular epithelium is provided passively by electrochemical and concentration gradients. The excretion of sodium from cells through the basolateral membranes occurs actively with the help of Na+/K+-ATPase. The remaining energy of cellular metabolism is lost in the transfer of sodium, the transport of which is primarily active. Sodium transport in cells can be achieved through various mechanisms. One of them is the exchange of Na + for H + (flow transport or antiport). In this case, the sodium ion is transported throughout the body, and the water ion is transferred to the body. Another way of sodium transfer in the cell occurs through the participation of amino acids and glucose. These are called cotransport and simport. Partially, sodium reabsorption is associated with potassium secretion.

Cardiac glycosides (strophanthin K, oubain) naturally inhibit the enzyme Na+/K+-ATPase, which ensures the transfer of sodium from the cell to the blood and the transport of potassium from the blood to the cell.

Of great importance in the mechanisms of reabsorption of water and sodium ions, as well as the concentration of waste, is the so-called rotary-flow breeding system. After passing the proximal section of the tubule, the isotonic filtrate must be removed from the loop of Henle. In this area, intense reabsorption of sodium is not accompanied by reabsorption of water, and there is little penetration of water from the wall of this section under the infusion of ADH. In connection with this, dilution occurs in the lumen of the nephron and the concentration of sodium in the interstitium. The diluted section in the distal part of the tubule consumes excess liquid, forming isotonic plasma. Changes in the isotonic section are found in the collection system located in the cerebellum, the high osmotic pressure in the interstitium is due to the increased concentration of sodium. At the collecting tubes, under the influx of ADH, the water will continue to boil until it reaches a concentration gradient. Passing through the cerebral ball, the vasa recta function as flow-exchange vessels that are taken up the path to the sodium papillae and are pressed until it turns to the cerebral ball. In the depth of the brain, such a layer maintains a high level of sodium, which ensures the resorption of water from the collection system and the concentration of the fluid.

Up to 80% of the filtered sodium is reabsorbed in the proximal segments of the tubules, while in the distal segments and collection tubes it is reabsorbed around 8 - 10%.

In the proximal segment, sodium is absorbed with an equivalent amount of water, and instead the canaliculus becomes isoosmotic. The proximal sections have high permeability of both sodium and water. Through the apical membrane, sodium enters passively into the cytoplasm behind a gradient of electrochemical potential. Then the sodium is transported by the cytoplasm to the basal part of the cell, where sodium pumps are located (Na-K-ATPase, stored in Mg).

Passive reabsorption of chlorine ions is observed in cellular contact areas that penetrate chlorine and other water. The penetration of interclinary spaces ceases to be a very constant value and can change under physiological and pathological conditions.

In the lower part of the loop of Henle, sodium and chlorine are practically not absorbed.

The outgoing part of the loop of Henle has another mechanism for absorbing sodium and chlorine. On the apical surface there is a system for transferring sodium and potassium ions and two chlorine ions into the body. There are also Na-K pumps on the basal surface.

The distal segment has a conductive salt reabsorption mechanism, a Na-pump, which ensures sodium reabsorption against a high concentration gradient. About 10% sodium is absorbed here. Reabsorption of chlorine occurs independently of sodium and passively.

In collecting tubes, sodium transport is regulated by aldosterone. Sodium enters through the sodium channel, collapses to the basement membrane and is transported to the post-peritoneal region by Na-K-ATPase.

Aldosterone is present in the distal convoluted tubules and cobalt collection tubes.

Potassium transport

The proximal segments absorb 90-95% potassium, which is filtered. Some potassium is absorbed at the loop of Henle. The potassium seen from the section lies in the secretion of the cells of the distal canaliculus and collecting tubes. With an excessive supply of potassium in the body, reabsorption in the proximal tubules does not decrease, but secretion in the distal tubules sharply increases.

In all pathological processes that are accompanied by a reduced filtration function, there is an increase in the secretion of potassium in the tubules of the liver.

In the same compartment of the distal canaliculus and collecting tubes there are systems for potassium reabsorption and secretion. If there is a deficiency of potassium, it will ensure maximum absorption of potassium from the body, and if there is an excess, it will ensure its secretion.

Secretion of potassium through the cells into the lumen of the tubule is a passive process, which follows a concentration gradient, and reabsorption is active. The increased secretion of potassium under the infusion of aldosterone is due not only to the effect of the remaining potassium penetration, but also to the increased supply of potassium into the cell due to the strengthening of the Na-K pump.

Another important factor regulating the transport of potassium in the tubules is insulin, which changes the excretion of potassium. A great influx of potassium into the rhubarb causes the rise of acid-water flow. Alkalosis is accompanied by an increase in the presence of potassium and nitric acid, and acidosis leads to a change in kaliuresis.

Calcium transport

Nibs and cysts play a major role in maintaining a stable level of calcium in the blood. For a supplement of calcium intake it is approximately 1 g. For the intestines it is 0.8, for the liver - 0.1-0.3 g/amount. In the glomeruli, calcium ionization is filtered, which appears in the form of low-molecular complexes. In the proximal tubules, 50% of calcium is reabsorbed, which is filtered, in the outgoing leg of the loop of Henle - 20-25%, in the distal tubules - 5-10, in collecting tubes - 0.5-1.0%.

There is no calcium secretion in humans.

In cells, calcium follows a concentration gradient and is concentrated in the endoplasmic reticulum and in mitochondria. Calcium is excreted from the body in two ways: through the calcium pump (Ca-ATPase) and through the Na/Ca exchanger.

The nitric tubule has a particularly effective system for stabilizing the level of calcium, the fragments of the veins continuously pass through the apical membrane, and the weakening of transport into the blood would not only destroy the balance of calcium in the body, but also the would cause pathological changes in the nephron itself.

Hormones that regulate calcium transport in calcium:

• Parathyroid hormone
• Thyrocalcitonin
• Growth hormone

Among the hormones that regulate calcium transport in humans, the most important is parathyroid hormone. It changes the reabsorption of calcium in the proximal tubule, which reduces its excretion due to the stimulation of calcium uptake in the distal segment of the nephron and collecting tubes.

In opposition to parathyroid hormone, thyrocalcitonin causes increased excretion of calcium and calcium. The active form of vitamin D3 increases the reabsorption of calcium in the proximal segment of the tubule. Somatotropic hormone consumes a lot of calcium, which is why patients with acromegaly often develop a disease.

Transport of magnesium

A healthy adult person expects 60-120 mg of magnesium per meal. Up to 60% of the magnesium that is filtered is reabsorbed in the proximal tubules. A large amount of magnesium is reabsorbed at the outgoing leg of the loop of Henle. Magnesium reabsorption is an active process and is limited by the magnitude of maximum tubular transport. Hypermagnesemia leads to increased excretion of low magnesium and may be accompanied by short-term hypercalcification.

With a normal level of glomerular filtration, the glomerular filtration level effectively copes with changes in the level of magnesium in the blood, leading to hypermagnesemia, and the clinician is more often required to treat This is due to hypomagnesia. Magnesium, like calcium, is not secreted in the tubules.

The fluidity of magnesium excretion increases with an acute increase in post-peritoneal blood pressure, with an increase in thyrocalcitonin and ADH. Parathyroid hormone is replaced by magnesium. However, hyperparathyroidism is accompanied by hypomagnesemia. This is probably associated with hypercalcemia, as there is greater excretion of both calcium and magnesium in minerals.

Transport of phosphorus

Nirks play a key role in maintaining phosphate levels in the internal midstream. In blood plasma, phosphates appear to be large (about 80%) and protein-bound ions. For each dose, there is approximately 400–800 mg of inorganic phosphorus. 60-70% of phosphates that are filtered are absorbed in the proximal tubules, 5-10% - in the loop of Henle and 10-25% - in the distal tubules and collecting tubes. If the transport system of the proximal tubules is sharply reduced, then the tension of the distal segment of the nephron begins to increase, which can be affected by phosphaturia.

In the regulation of tubular transport of phosphates, the main role belongs to the parathyroid hormone, which suppresses reabsorption in the proximal segments of the nephron, vitamin D3, somatotropic hormone, which stimulates the reabsorption of phosphates.

Glucose transport

Glucose that has passed through the glomerular filter is almost completely reabsorbed in the proximal segments of the tubules. You can get up to 150 mg of glucose per dose. Glucose reabsorption occurs actively through the participation of enzymes, energy loss and acid production. Glucose passes through the membrane simultaneously with sodium against a high concentration gradient.

In the cell, there is accumulation of glucose, phosphorylation to glucose-6-phosphate and passive transfer to the intracanalicular region.

Complete reabsorption of glucose is only achieved in these phases, if the number of carriers and the fluidity of their flow through the tissue membrane ensure the transfer of all glucose molecules that were found in the lumens of the proximal organs to anals and nirkovic taurus. The maximum amount of glucose that can be reabsorbed in the tubules with the constant involvement of all transporters is 375 ± 80 in men and 303 ± 55 mg/min in women.

The level of glucose in the blood, in any case, is still 8-10 mmol/l.

Squirrel transport

Normally, the protein that is filtered in the glomeruli (up to 17-20 g/day), almost all of it is reabsorbed in the proximal segments of the tubules and in the additional section appears in a small amount - from 10 to 100 mg. Tubular protein transport is an active process in which proteolytic enzymes take part. Protein reabsorption is affected by pinocytosis in the proximal segments of the tubules.

Under the infusion of proteolytic enzymes, such as those found in lysosomes, the protein undergoes hydrolysis with the addition of amino acids. Penetrating through the basement membrane, amino acids arrive at the periocanalicular region.

Transport of amino acids

In the glomerular filtrate, the concentration of amino acids is the same as in blood plasma - 2.5-3.5 mmol/l. Normally, the renal fluid is absorbed by approximately 99% of amino acids, and this process occurs mainly in the coliforms of the proximal convoluted tubule. The mechanism of reabsorption of amino acids is similar to that described for glucose. A number of carriers are surrounded, and if all of them are connected with essential amino acids, the excess of the remaining ones is lost in the canalicular region and is eliminated from the section.

The norm is to contain less than a trace of amino acids.

The causes of aminoaciduria are:

• Increased concentration of amino acids in plasma during increased absorption into the body and when their metabolism is disrupted, which leads to re-engineering of the transport system of tubules of low acidity and aminoaciduria
• defect of the transporter, which ensures the reabsorption of amino acids
• a defect in the apical membrane of the tubules, which leads to increased penetration of the brush lining and the area of ​​interclinary contacts. As a result, the renal flow of amino acids in the tubules is indicated
• disruption of the metabolism of proximal tubule cells