Amazing functions of the kidneys in the human body. Prevention of violations of renal activity. Common kidney diseases

One of the important filtration organs in the human body is the kidneys. This paired organ is located in the retroperitoneal space, namely on the posterior surface of the abdominal cavity in the lumbar region on both sides of the spine. The right organ is anatomically located slightly lower than the left. Many of us believe that the only function of the kidneys is to produce and excrete urine. However, in addition to the excretory function, the kidneys have many other tasks. In our article, we will take a closer look at what the kidneys do.

Peculiarities

Each kidney is surrounded by a sheath of connective and adipose tissue. Normally, the dimensions of the organ are as follows: width - no more than 60 mm, length - about 10-12 cm, thickness - no more than 4 cm. The weight of one kidney reaches 200 g, which is half a percent of the total weight of a person. In this case, the body consumes oxygen in the amount of 10% of the total oxygen demand of the body.

Despite the fact that normally there should be two kidneys, a person can live with one organ. Often, one or even three kidneys are present from birth. If, after the loss of one organ, the second copes with the double assigned load, then a person can fully exist, but he needs to beware of infections and heavy physical exertion.

The structure and formation of urine

Responsible for the work of the kidneys are nephrons - the main structural unit of the body. Each kidney has about a million nephrons. They are responsible for the production of urine. To understand what function the kidneys perform, it is necessary to understand the structure of the nephron. Each structural unit contains a body with a capillary glomerulus inside, surrounded by a capsule, which consists of two layers. The inner layer consists of epithelial cells, and the outer layer consists of tubules and a membrane.

Various functions of the human kidneys are realized due to the fact that there are three types of nephrons depending on the structure of their tubules and the location:

Intracortical.
Surface.
Juxtamedullary.

The main artery is responsible for transporting blood to the organ, which inside the kidney is divided into arterioles, each of which brings blood to the renal glomerulus. There is also an arteriole that drains blood from the glomerulus. Its diameter is smaller than that of the adductor arteriole. Due to this, the necessary pressure is constantly maintained inside the glomerulus.

In the kidneys, there is always constant blood flow even against the background of increased pressure. A significant reduction in blood flow occurs with kidney disease, due to severe stress or severe blood loss.

The main function of the kidneys is the secretion of urine. This process is possible due to glomerular filtration, subsequent tubular secretion and reabsorption. The formation of urine in the kidneys occurs as follows:

First, blood plasma components and water are filtered through a three-layer glomerular filter. Formed plasma elements and proteins easily pass through this filtering layer. Filtration is carried out due to constant pressure in the capillaries inside the glomeruli.
Primary urine accumulates inside the collecting cups and tubules. Nutrients and fluids are absorbed from this physiological primary urine.
Next, tubular secretion is carried out, namely the procedure for cleaning the blood from unnecessary substances and transporting them into the urine.

Regulation of kidney activity

Hormones have a certain effect on the excretory functions of the kidney, namely:

Adrenaline, produced by the adrenal glands, is needed to reduce urination.
Aldosterone is a special steroid hormone produced by the adrenal cortex. The lack of this hormone leads to dehydration, salt imbalance and a decrease in blood volume. An excess of the hormone aldosterone contributes to the retention of salt and fluid in the body. This in turn leads to edema, heart failure and hypertension.
Vasopressin is synthesized by the hypothalamus and is a peptide hormone that regulates fluid absorption in the kidneys. After drinking a large amount of water or when its content in the body is exceeded, the activity of the hypothalamus receptors decreases, which contributes to an increase in the volume of fluid excreted by the kidneys. With a lack of water in the body, the activity of receptors increases, which in turn leads to a decrease in urine secretion.

Important: against the background of damage to the hypothalamus, the patient has increased diuresis (up to 5 liters of urine per day).

Parahormone is produced by the thyroid gland and regulates the process of removing salts from the human body.
Estradiol is considered a female sex hormone that regulates the level of phosphorus and calcium salts in the body.

renal functions

The following functions of the kidneys in the human body can be listed:

homeostatic;
excretory or excretory;
metabolic;
protective;
endocrine.

excretory

The excretory role of the kidneys is to filter the blood, cleanse it of metabolic products and remove them from the body. At the same time, the blood is cleared of creatinine, urea, and various toxins, such as ammonia. Various unnecessary organic compounds (amino acids and glucose), mineral salts that entered the body with food are also removed. The kidneys excrete excess fluid. The excretory function involves the processes of filtration, reabsorption, and renal secretion.

At the same time, 1500 liters of blood are filtered through the kidneys in one day. Moreover, approximately 175 liters of primary urine are immediately filtered. But since fluid absorption occurs, the amount of primary urine is reduced to 500 ml - 2 liters and is excreted through the urinary system. At the same time, urine is 95 percent liquid, and the remaining five percent is dry matter.

Attention: in case of violation of the excretory function of the organ, the accumulation of toxic substances and metabolic products in the blood occurs, which leads to general intoxication of the body and subsequent problems.

Homeostatic and metabolic functions

Do not underestimate the importance of the kidneys in regulating the volume of intercellular fluid and blood in the human body. Also, this organ is involved in the regulation of ionic balance, removing excess ions and protons of bicarbonate from the blood plasma. It is able to maintain the required volume of fluid in our body by adjusting the ionic composition.

Paired organs are involved in the breakdown of peptides and amino acids, as well as in the metabolism of lipids, proteins, carbohydrates. It is in this organ that ordinary vitamin D is transformed into its active form, namely vitamin D3, which is necessary for the normal absorption of calcium. Also, the kidneys are an active participant in protein synthesis.

Endocrine and protective functions

The kidneys are an active participant in the synthesis of the following substances and compounds necessary for the body:

renin is a substance that promotes the production of angiotensin 2, which has a vasoconstrictive effect and regulates blood pressure;
calcitriol is a special hormone that regulates calcium metabolism in the body;
erythropoietin is necessary for the formation of bone marrow cells;
prostaglandins are substances involved in the regulation of blood pressure.

As for the protective function of the body, it is associated with the removal of toxic substances from the body. These include some drugs, ethyl alcohol, narcotic substances, including nicotine.

Prevention of violations of renal activity

Overweight, hypertension, diabetes mellitus and some chronic diseases affect the functioning of the kidneys in a negative way. For them, hormonal drugs and nephrotoxic drugs are harmful. The activity of the body may suffer due to a sedentary lifestyle, as this will contribute to the disruption of salt and water metabolism. It can also lead to the deposition of kidney stones. Causes of kidney failure include:

traumatic shock;
infectious diseases;
poisoning with poisons;
violation of the outflow of urine.

For the normal functioning of the body, it is useful to drink 2 liters of liquid per day. It is useful to drink berry fruit drinks, green tea, purified non-mineral water, parsley decoction, weak tea with lemon and honey. All these drinks are a good prevention of stone deposition. Also, to preserve the health of the body, it is better to give up salty foods, alcoholic and carbonated drinks, coffee.

The excretory process in the body is very important for homeostasis. It promotes the removal of various metabolic products that can no longer be used, toxic and foreign substances, excess salt, organic compounds and water.

The excretory process involves the lungs, digestive tract, and skin, but the most important function in this process is performed by the kidneys. This excretory organ contributes to the excretion of substances formed as a result of or ingested with food.

What are kidneys and where are they located?

The kidneys are an organ that is part of the urinary system, which can be compared to a sewage treatment plant.

Approximately 1.5 liters of blood passes through them in one minute, being cleansed of toxic substances. The kidneys are located at the posterior wall of the peritoneum at the level of the lower back on both sides of the spine.

Despite the fact that this organ has a dense texture, its tissue consists of a large number of tiny elements called nephrons. There are about 1 million of these elements in one kidney. At the top of each of them there is a malpighian glomerulus, lowered into a hermetically sealed cup (Shumlyansky-Bowman capsule). Each kidney has a strong capsule and is fed by the blood that enters it.

Anatomical structure of the kidneys:

upper pole;
renal papilla;
renal pillars;
renal sinus;
small renal cup;

large renal calyx;
pelvis;
cortex;
ureter;
bottom pole.

Each kidney consists of two layers: dark cortical (located on top) and lower cerebral (located below). In the cortical layer there is a mass of blood vessels and the initial sections of the renal canals. Nephrons are made up of tubules and tangles where urine is formed. This process is quite complex, because about a million of these units are involved in it. Scientists have proved that such an organ as the kidneys can serve a person for about 800 years, under favorable conditions.

In diabetes mellitus, irreversible processes occur in the kidneys, consisting in vascular damage.

This impairs blood circulation and disrupts the functioning of the internal organs responsible for the urinary processes in the body. In medicine, such disorders are called. It is the excess sugar in the body that eats away the vessels from the inside, which leads to rather serious consequences.

The functions of the kidneys in the human body

In addition to the removal of harmful substances, the normalization of blood pressure and the formation of urine, the kidneys perform the following functions:

Hematopoiesis - produce a hormone that regulates the formation of red blood cells that saturate the body with oxygen.
Filtration - form urine and separate harmful substances from useful ones (proteins, sugar and vitamins).
Osmotic pressure - balance vital salts in the body.
Protein regulation - control a protein level called oncotic pressure.

When kidney function is impaired, various diseases develop that lead to kidney failure. At an early stage, this disease, and its presence can be determined by passing a urine and blood test.

The impact of diabetes on the kidneys: prognosis and prevention

Diabetes mellitus today is a fairly common disease of the endocrine system, which affects about 1-3% of adults on the planet.

Over time, the number of patients with this disease increases, which turns it into a real problem that medicine has yet to solve. Diabetes has a complex course and over time without adequate treatment leads to the development of serious complications.

In type 2 diabetes, the likelihood of developing kidney disease is about 5%, and in type 1 diabetes, it is about 30%.

The main problem in diabetes is the narrowing of the lumen of the blood vessels, which leads to a decrease in blood flow to the internal organs. In the initial stages of diabetes, kidney function is usually faster, as much more glucose passes through them than in a healthy person. Glucose pulls more fluid through the kidneys, which increases the pressure inside the glomeruli. This is called an increase in glomerular filtration rate.

In the initial stages of diabetes, there is a thickening of the membrane that surrounds the glomeruli, as well as a thickening of other tissues adjacent to it. Expanded membranes gradually displace the internal capillaries located in these glomeruli, which leads to the fact that the kidneys lose the ability to purify a sufficient volume of blood. The human body has spare glomeruli, so if one kidney is damaged, blood purification continues.

The development of nephropathy occurs only in 50% of hypertensive patients with diabetes mellitus.

Not everyone with diabetes develops kidney damage leading to kidney failure. In the high-risk group are those suffering from increased. In order to prevent kidney damage in diabetes, it is recommended to control the level of sugar in the blood stream, undergo preventive examinations and periodically take urine and blood tests.

The kidneys are one of the vital organs in the human body, they perform more than one function. Metabolic, protective, excretory, homeostatic and endocrine are the functions of the kidneys. A healthy person has a pair of kidneys, although there are cases when one of the kidneys is removed under the threat of life, then throughout the life of the patient, his health is at risk.

Throughout the day, the kidneys pass through themselves all the blood that is in the body. In one minute, one liter of blood passes through the kidneys, from this blood the kidneys select all the harmful substances that should go to the blood plasma, after which the harmful microbes enter the ureter, and only after that they end up in the bladder. When a person defecates, harmful substances are excreted from the human body along with urine.

Thanks to the valve that is in the ureter, the toxins cannot go back because it only opens in one direction. During the day, the kidneys pump about 200 liters of blood through themselves, thereby removing toxins from the body and making the blood sterile. And this, you see, is a very important function for human health and life, which is the main one.

Also in the kidneys is the synthesis of essential hormones, such as renin, erythropoietin and prostaglandin. Water in the human body is retained due to the hormone renin, prostaglandin regulates blood pressure, and the number of red blood cells is regulated by erythropoietin.

In the kidneys, the synthesis of various vitamins and microelements takes place, without which human life is not possible. Thanks to the ability of the kidneys to synthesize in the body, the balance of carbohydrates, proteins and lipids is maintained.

Summing up, we can say that the kidneys perform such functions in the body, without which further human life is not possible. Therefore, everyone should protect the kidneys and the health of the whole organism.

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The kidneys are of great importance in the human body. They perform a number of vital functions. Humans normally have two organs. Therefore, there are types of kidneys - right and left. A person can live with one of them, but the vital activity of the organism will be under constant threat, because its resistance to infections will decrease tenfold.

The kidney is a paired organ. This means that normally a person has two of them. Each organ is bean-shaped and belongs to the urinary system. However, the main functions of the kidneys are not limited to the excretory function.

The organs are located in the lumbar region on the right and left between the thoracic and lumbar spine. The location of the right kidney is slightly lower than the left one. This is due to the fact that above it is the liver, which prevents the kidney from moving upward.

The kidneys are approximately equal in size: they are 11.5 to 12.5 cm long, 3 to 4 cm thick, 5 to 6 cm wide, and weigh 120 to 200 g. The right one tends to be slightly smaller. .

What is the physiology of the kidneys? The organ is covered with a capsule from the outside, which reliably protects it. In addition, each kidney consists of a system whose functions are reduced to the accumulation and excretion of urine, as well as of the parenchyma. The parenchyma consists of the cortex (its outer layer) and the medulla (its inner layer). The urinary storage system is the small renal calyces. The small calyces fuse to form the large calyces. The latter are also connected and together form the renal pelvis. And the pelvis is connected to the ureter. In humans, respectively, there are two ureters that enter the bladder.

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In addition, the organs are equipped with a structural and functional unit called the nephron. The nephron is considered the most important unit of the kidney. Each of the organs contains more than one nephron, but has about 1 million of them. Each nephron is responsible for the functioning of the kidneys in the human body. It is the nephron that is responsible for the process of urination. Most of the nephrons are located in the cortex of the kidney.

Each structurally functional unit of the nephron is a whole system. This system consists of the Shumlyansky-Bowman capsule, the glomerulus, and the tubules that pass into each other. Each glomerulus is a system of capillaries that supplies blood to the kidney. Loops of these capillaries are located in the cavity of the capsule, which is located between its two walls. The cavity of the capsule passes into the cavity of the tubules. These tubules form a loop penetrating from the cortex into the medulla. In the latter there are nephron and excretory tubules. Urine is excreted through the second tubules into the cups.

The medulla forms pyramids with apexes. Each top of the pyramid ends with papillae, and they enter the cavity of the small calyx. In the area of the papillae, all excretory tubules unite.

The structural functional unit of the kidney, the nephron, ensures the proper functioning of the organs. If the nephron were absent, the organs would not be able to perform the functions assigned to them.

The physiology of the kidneys includes not only the nephron, but also other systems that ensure the functioning of the organs. So, the renal arteries depart from the aorta. Thanks to them, the blood supply to the kidney occurs. Nervous regulation of organ function is carried out with the help of nerves that penetrate from the celiac plexus directly into the kidneys. The sensitivity of the capsule of the kidneys is also possible due to the nerves.

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To understand how the kidneys work, first of all, you need to understand what functions are assigned to them. These include the following:

excretory, or excretory;
osmoregulatory;
ion-regulating;
intrasecretory, or endocrine;
metabolic;
hematopoietic (takes a direct part in this process);
concentration function of the kidneys.

During the day, they pump the entire volume of blood. The number of repetitions of this process is huge. About 1 liter of blood is pumped in 1 minute. At the same time, the organs select from the pumped blood all decay products, toxins, microbes and other substances harmful to the human body. Then all these substances enter the blood plasma. Then all this is sent to the ureters, and from there to the bladder. After that, harmful substances leave the human body when emptying the bladder.

When toxins enter the ureters, there is no way back into the body. Thanks to a special valve located in the organs, the re-entry of toxins into the body is absolutely excluded. This is made possible by the fact that the valve opens in only one direction.

Thus, pumping over 200 liters of blood per day, the organs guard its purity. From slagged with toxins and microbes, the blood becomes clean. This is extremely important, since blood bathes every cell of the human body, so it is vital that it be cleansed.

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So, the main function that organs perform is excretory. It is also called excretory. The excretory function of the kidneys is responsible for filtration and secretion. These processes occur with the participation of the glomerulus and tubules. In particular, the filtration process is carried out in the glomerulus, and the processes of secretion and reabsorption of substances that need to be removed from the body are carried out in the tubules. The excretory function of the kidneys is very important, as it is responsible for the formation of urine and ensures its normal excretion (excretion) from the body.

The endocrine function consists in the synthesis of certain hormones. First of all, this concerns renin, due to which water is retained in the human body and the volume of circulating blood is regulated. The hormone erythropoietin is also important, which stimulates the creation of red blood cells in the bone marrow. Finally, organs synthesize prostaglandins. These are substances that regulate blood pressure.

The metabolic function lies in the fact that it is in the kidneys that microelements and substances vital for the functioning of the body are synthesized and transformed into even more important ones. For example, vitamin D is converted to D3. Both vitamins are essential for humans, but vitamin D3 is the more active form of vitamin D. This function also maintains an optimal balance of proteins, carbohydrates and lipids in the body.

The ion-regulating function implies the regulation of the acid-base balance, for which these organs are also responsible. Thanks to them, the acid and alkaline components of blood plasma are maintained in a stable and optimal ratio. Both organs secrete, if necessary, an excess of bicarbonate or hydrogen, due to which this balance is maintained.

The osmoregulatory function is to maintain the concentration of osmotically active blood substances under various water regimes to which the body may be exposed.

The hematopoietic function means the participation of both organs in the process of hematopoiesis and blood purification from toxins, microbes, harmful bacteria and toxins.

The concentrating function of the kidneys means that they concentrate and dilute urine by excreting water and solutes (primarily urea). The organs must do this almost independently of each other. When urine is diluted, more water is excreted than solutes. On the contrary, concentration releases a larger volume of solutes rather than water. The concentration function of the kidneys is extremely important for the life of the entire human body.

Thus, it becomes clear that the importance of the kidneys and their role for the body is so great that it is difficult to overestimate them.

That is why it is so important to pay due attention to this and consult a doctor at the slightest disturbance in the functioning of these organs. Since many processes in the body depend on the work of these organs, the restoration of kidney function becomes an extremely important event.

Almost all the functions of the kidneys in our body are irreplaceable and vital, and with various violations of their normal work, most organs and systems of the human body suffer. Thanks to the activity of the kidneys, the constancy of the internal environment of the body (homeostasis) is maintained. When any irreversible pathological process occurs in this organ, the consequences of the disease become extremely severe, and sometimes fatal.

If we consider the question of what function the kidneys perform in the human body and what life support processes they control, first of all, it is necessary to get acquainted with the structural features of all components of this organ (especially at the cellular level).

Normally, a person from birth has two kidneys, which are located symmetrically from the spinal column in his thoracolumbar region. If developmental anomalies occur, a child may be born with three or, conversely, one kidney.

The organ has a bean-shaped form, and outside it is covered with a dense capsule, consisting of a connective tissue component. The outer layer is called the cortical substance of the kidney, it occupies a smaller volume. The inner layer is called the "medulla", its basis is parenchymal tissue and stroma, which is abundantly penetrated by renal vessels and nerve fibers.

If we disassemble the process of accumulation of urine, then in a simplified version it looks like this: small cups merge with each other, forming large cups, and those, in turn, form a system of pelvises and open into the lumen of the ureter.

The morphofunctional unit of the kidney is the nephron, which is responsible for most of the functions of the kidneys in the human body. All nephrons are closely interconnected and represent a complex "uninterrupted" mechanism.

In their structure, the following structures are distinguished:

the glomerular apparatus (malpighian body), located in the thickness of the cortical substance, the main function of which is to filter the incoming blood;
a capsule that covers the outside of the glomerulus and acts as a "filter" through which the blood is cleansed of any kind of toxins and metabolic products;
a complex system of convoluted tubules that pass into each other and allow the reabsorption of the filtered fluid.

The tissues of each kidney contain at least 1 million actively functioning nephrons.

The work of all components of the nephron sequentially goes through three phases:

Filtration of blood plasma with the formation of primary urine (occurs in the glomeruli). During the day, approximately 200 liters of such urine is formed through the kidneys, which is close in composition to human plasma.
Reabsorption or the process of reabsorption is necessary so that the body does not lose the necessary substances in the urine (this occurs in the tubular system). Thus, vitamins, salts important to the body, glucose, amino acids and others are retained.
Secretion, in which all toxic products, unnecessary ions and other substances that are retained by the renal filter enter the final urinary sediment and are excreted irrevocably.

The work of the renal apparatus occurs in a constant mode, where one phase of the process smoothly replaces another

adrenal glands

When it comes to the structure and function of the kidneys, it is impossible not to mention that at the upper pole of this organ there are special paired formations called the adrenal glands. Despite the fact that they have a small volume, their functionality is unique and extremely necessary.

The adrenal glands consist of parenchyma and belong to a paired endocrine organ, which determines their main purpose in the human body. The oppression of their work leads to a number of serious disorders that require immediate medical intervention. Among the most common diseases that a specialist has to deal with, there is a pathology such as hypofunction of the adrenal glands (the production of certain hormones is sharply inhibited).

The adrenal glands are a vital organ for humans.

Functions of the kidneys and adrenal glands

The main function for which the kidneys are responsible is called excretory - this is the ability to form and, subsequently, excrete the end product of metabolism, namely urine. In the medical literature, one can come across the term "excretory" function, which is synonymous with the previous process.

The excretory (or excretory) activity of the kidneys includes the filtration and secretory functions, which were described above. Their main task is to remove toxins from the body through urinary sediment.

The final urine contains "unnecessary" waste products of the body

An equally important function of the kidneys is their ability to synthesize hormonal substances. The endocrine work of the body is associated with the entry into the blood of such hormones as:

renin (it is responsible for the balance of water in the body, prevents its excessive release and controls the constancy of blood volume in the circulatory bed);
erythropoietin (a substance that stimulates the production of red blood cells in bone marrow cells);
prostaglandins (control blood pressure).

The metabolic function of an organ lies in the fact that a number of biological substances are synthesized in its tissues or they are converted into active forms (for example, the inactive form of vitamin D in the kidneys changes its structure and becomes more active).

The kidneys are able to maintain the balance of the ionic composition of the plasma and maintain a constant osmotic pressure in the body.

The concentration function of the renal apparatus is that it is capable of concentrating urine, namely, increased excretion of dissolved substrates with it. When there is a failure in this function, then, on the contrary, the release of water increases, and not substances. Thus, the functional ability of the kidneys is reflected.

The most important functions of the adrenal glands are reflected in the following:

They are directly involved in many metabolic and metabolic processes.
They produce a number of vital hormonal substances that affect the functioning of individual body systems (mainly, these are the functions of the adrenal cortex).
Determine the behavior and reaction of the human body to stressful situations.
Thanks to the adrenal glands, the body's response to irritating external influences is formed.

The main function of the adrenal glands is the synthesis of hormonal substances.

Dysfunction

Entire books have been written about the possible factors and causes of dysfunctions in the activity of the kidneys, there are many syndromes, diseases and pathological conditions that are a consequence of a violation of one or another organ function. All of them are undoubtedly very important, but we will try to focus on the most important points.

When it comes to etiological factors, that is, the causes that led to kidney disease, the following groups should be distinguished among them.

Prerenal mechanisms are caused by processes that indirectly affect the functional activity of the organ. These include:

various kinds of mental states, disorders in the work of the nervous system, as a result of which the development of reflex urinary retention is possible, up to its complete absence;
pathology of an endocrine nature, leading to a violation in the synthesis of hormonal substances that can affect the functioning of the kidney;
impaired blood supply to the organ during general hypotensive processes (for example, during collapse) or during a hypertensive crisis.

Renal mechanisms imply direct damage to the tissues of the kidney (inflammatory or autoimmune diseases, thrombosis, aneurysm or atherosclerosis of the renal vessels, and others).

Postrenal damage mechanisms are triggered when obstacles arise in the way of the natural outflow of urine (blockage of the lumen of the ureter by a stone, compression by a tumor process, and others).

The main types of acute renal failure

Development mechanisms

When exposed to any of the above factors, there are violations associated with a change in the processes of filtration, reabsorption or excretion.

Filtration changes can manifest themselves:

a decrease in the volume of filtered plasma in the glomerular apparatus (in hypotonic conditions, necrotic or sclerotic processes in the tissues of the glomeruli);
an increase in the volume of filtered plasma (hypertensive conditions, inflammatory processes leading to increased permeability of the glomerular membrane).

Changes in reabsorption are characterized by a slowdown in this process, which is most often associated with genetic abnormalities at the enzyme level.

Violation of excretion is manifested in the retention of toxic substances in the body and their adverse effects on the entire body, possibly with glomerulonephritis of various etiologies, ischemic kidney disease and others.

The work of the kidneys is evaluated according to the following characteristics:

Indicators of diuresis, that is, the amount of urine excreted during the day. Normally, a person excretes slightly less urine than he drinks liquids, and in case of pathology, the development of polyuria, oliguria or anuria is likely.
The density of the urinary sediment (normal ranges from 1008 to 1028). In pathology, they speak of hyperstenuria, hypostenuria or isosthenuria.
The components that make up urine and their quantitative ratio (we are talking about leukocytes, erythrocytes, protein, cylinders and others).

The functional work of the kidneys is assessed according to a number of diagnostic criteria for urinary sediment.

Renal failure is a complex of symptoms and syndromes, the development of which is due to a decrease or complete cessation of urine output. There is an accumulation of toxic metabolic products that "poison" the body.

An acute process develops literally within a few hours, and its main sign is the progression and disorder of all vital processes.

Chronic insufficiency can develop for many years, this is due to the gradual death of nephrons.

To restore the impaired functions of the renal apparatus, they resort to etiotropic and pathogenetic therapy, but do not forget about symptomatic treatment.

Etiotropic therapy includes the complete elimination or maximum correction of all causes that have become the source of the disease.

The principles of pathogenetic treatment are to block certain links of the disease, which allows you to start the restoration of kidney function and their natural work. For this purpose, drugs are used that can suppress the immune system, or, conversely, stimulate the protective properties of the body, perform hemodialysis procedures and others.

Conducting sessions of hemodialysis blood purification helps the human body fight the toxic effects of harmful substances and toxins

Symptomatic therapy includes a huge range of drugs that restore and correct the consequences of improper kidney function (antihypertensive, diuretic drugs, and others).

Unfortunately, kidney pathology is very common and affects the able-bodied segments of the population, both among women and men. If functional disorders are not diagnosed in time, then there is a risk of a protracted course of the process, which often causes disability.

Various functions of the human kidneys are realized due to the fact that there are three types of nephrons depending on the structure of their tubules and the location:

Intracortical.
Surface.
Juxtamedullary.

First, blood plasma components and water are filtered through a three-layer glomerular filter. Formed plasma elements and proteins easily pass through this filtering layer. Filtration is carried out due to constant pressure in the capillaries inside the glomeruli.
Primary urine accumulates inside the collecting cups and tubules. Nutrients and fluids are absorbed from this physiological primary urine.
Next, tubular secretion is carried out, namely the procedure for cleaning the blood from unnecessary substances and transporting them into the urine.

Hormones have a certain effect on the excretory functions of the kidney, namely:

Adrenaline, produced by the adrenal glands, is needed to reduce urination.
Aldosterone is a special steroid hormone produced by the adrenal cortex. The lack of this hormone leads to dehydration, salt imbalance and a decrease in blood volume. An excess of the hormone aldosterone contributes to the retention of salt and fluid in the body. This in turn leads to edema, heart failure and hypertension.
Vasopressin is synthesized by the hypothalamus and is a peptide hormone that regulates fluid absorption in the kidneys. After drinking a large amount of water or when its content in the body is exceeded, the activity of the hypothalamus receptors decreases, which contributes to an increase in the volume of fluid excreted by the kidneys. With a lack of water in the body, the activity of receptors increases, which in turn leads to a decrease in urine secretion.

Important: against the background of damage to the hypothalamus, the patient has increased diuresis (up to 5 liters of urine per day).

Parahormone is produced by the thyroid gland and regulates the process of removing salts from the human body.
Estradiol is considered a female sex hormone that regulates the level of phosphorus and calcium salts in the body.

The following functions of the kidneys in the human body can be listed:

homeostatic;
excretory or excretory;
metabolic;
protective;
endocrine.

Attention: in case of violation of the excretory function of the organ, the accumulation of toxic substances and metabolic products in the blood occurs, which leads to general intoxication of the body and subsequent problems.

The kidneys are an active participant in the synthesis of the following substances and compounds necessary for the body:

renin is a substance that promotes the production of angiotensin 2, which has a vasoconstrictive effect and regulates blood pressure;
calcitriol is a special hormone that regulates calcium metabolism in the body;
erythropoietin is necessary for the formation of bone marrow cells;
prostaglandins are substances involved in the regulation of blood pressure.

As for the protective function of the body, it is associated with the removal of toxic substances from the body. These include some drugs, ethyl alcohol, narcotic substances, including nicotine.

traumatic shock;
infectious diseases;
poisoning with poisons;
violation of the outflow of urine.

The kidneys serve as a natural "filter" of the blood, which, when properly functioning, remove harmful substances from the body. The regulation of kidney function in the body is vital for the stable functioning of the body and the immune system. For a comfortable life, two organs are needed. There are times when a person stays with one of them - it is possible to live, but you will have to depend on hospitals all your life, and protection against infections will decrease several times. What are the kidneys responsible for, why are they needed in the human body? To do this, you should study their functions.

Let's delve a little into the anatomy: the excretory organs include the kidneys - this is a paired bean-shaped organ. They are located in the lumbar region, while the left kidney is higher. Such is nature: above the right kidney is the liver, which does not allow it to move anywhere. Regarding the size, the organs are almost the same, but note that the right one is slightly smaller.

What is their anatomy? Externally, the organ is covered with a protective shell, and inside it organizes a system capable of accumulating and removing fluid. In addition, the system includes parenchyma, which create the medulla and cortex and provide the outer and inner layers. Parenchyma - a set of basic elements that are limited to the connective base and shell. The accumulation system is represented by a small renal calyx, which forms a large one in the system. The connection of the latter forms a pelvis. In turn, the pelvis is connected to the bladder through the ureters.

The functions of the kidneys cannot be overestimated: they are vital organs and participate in many important processes of human life.

Three main functions of the kidneys

Blood filtration. In the human body, the kidneys act as a blood filter, and also remove excess fluid, urea, toxins, and creatinine. For the whole day, approximately 1.5 liters of blood passes through the kidneys and is excreted from 0.5 liters. up to 2 l. urine.
Maintaining the balance of water-salt balance. The kidneys regulate the content of minerals and salts in the blood. In case of their excess, the kidneys help to remove them from the body.
Production of biological substances. The following hormones are produced in the kidneys:
- Erythropoietin is a hormone that stimulates the uptake of vitamin B12, iron and copper by the bone marrow. An increase in this substance in the blood increases blood pressure and increases blood viscosity;
- Thrombopoietin - a protein produced by the liver and kidneys, it stimulates the number of platelets produced by the bone marrow;
- Calcitriol is a processed form of vitamin D. It acts as a regulator of potassium and phosphate metabolism. A lack of calcitriol production in a child's body can cause rickets.

Also, amino acids and easily digestible vitamin D3 are synthesized in the kidneys from vitamin D. This active form of the vitamin is necessary for the full breakdown and absorption of calcium from the gastrointestinal tract.

Controlling the concentration of sodium in the blood

Within a month, the kidneys are able to compensate for the daily need for sodium. This feature is important when it is required to reduce the amount of salt consumed. Therefore, when a salt-free diet is recommended to patients, this does not harm their health in any way (but such a diet should be followed no longer than 40 days and strictly under the supervision of a doctor).

Now you know what the kidneys do. It's also good to know what they look like. Each of the kidneys weighs no more than 200 g. The kidneys are small in size: 10-12 cm long, 5-6 cm wide, and 4 cm thick, similar in shape to beans. The kidneys are located on the right and left sides of the spine, one slightly lower than the other.

Nature has endowed people with such strong kidneys that even if they function at 20%, this will help maintain the vital activity of the body. Our well-being, blood composition, the state of the bone marrow and the body as a whole depend on the kidneys. These small but very important organs need to be protected and preserved for as long as possible.

The kidneys are paired organs of the urinary system, located on either side of the spine.

human kidney

The main functional structural unit of the kidney is the nephron, which is a system of tubes penetrating the entire parenchyma of the organ.

The main chemical reactions take place in the renal glomerulus and tubules. They pass only if the neutral charge of the membrane is observed and the electrochemical gradient is observed.

The role of these formations is very difficult to overestimate. They play an important function, cleansing the body of toxins, harmful substances, and salts.

It is difficult not to pay attention to the fact that nature has rewarded us with a very high endurance limit - even if 80-85% of nephrons die in a person for some reason, then functionally a person will not feel this.

homeostatic. The kidneys maintain acid-base balance, metabolism of uric acid, creatinine, regulation of the amount of blood bicarbonates;
excretory function. The kidneys remove the products of the final nitrogen metabolism of the blood, maintaining the water and electrolyte balance, removing excess water;
metabolic function. The kidneys take the first place in the regulation of all types of metabolism (protein, carbohydrate, fat, vitamin);
endocrine function. Renin, angiotensin, prostaglandin are the main regulators of blood pressure, produced only in the renal parenchyma, erythropoietin is the main hematopoietic hormone, without which bone marrow stem cells will not multiply.

Causes of kidney dysfunction:

prerenal - these are the causes of impaired blood supply to the kidneys. This includes a sharp drop in blood pressure, shock of any etiology (traumatic, hypovolemic and other types);
renal - conditions in which the pathological process affects the renal parenchyma (glomerulonephritis, pyelonephritis);
postrenal - acute violation of the outflow of urine (urolithiasis, tumor processes of neighboring organs, compression of the ureter by a hematoma, urethral stricture).

The structure of the nephron

Stages of operation of kidney filters:

nephrons purify blood plasma: at this stage, ultrafiltration reabsorption (absorption) takes place. The essence of the first process is the formation of primary urine, which has a very similar composition to blood plasma. Its volume can reach about 15 liters.

The process of reabsorption is as follows: passing through the tubular systems, the primary urine is highly concentrated, the water necessary for the functioning of the body, glucose, some vitamins, amino acids are removed from it;

The renal pelvis collects filtered urine and carries it to the bladder through the ureters. This process occurs due to the presence of special receptors located in the wall of the above formations that respond to stretching.

As for the removal of hydrogen and ammonia ions, this process is essential for our well-being and vitality.

Ammonia molecules

Hydrogen with ammonia ions is needed by a person to maintain the acid-base state of the internal environment of the body.

Hydrogen protons are released into the urine in exchange for sodium ions and for a bicarbonate ion under the action of a specific enzyme called carbonate dehydratase.

The excretion of ammonia into the urine is also an extremely complex and necessary process, since this compound is very toxic.

But here, too, mother nature took care of us - as soon as the ammonia molecules enter the lumen of the renal tubule, they immediately bind with hydrogen ions and cannot go back into the blood.

But with some metabolic disorders, the processes of removing ammonia can be very strongly suppressed or even stopped.

The first factor that has a significant impact on this process is the value of the acid-base state of the blood.

If alkalosis (alkalinization of the blood) is observed in the blood, then the production of ammonia ions decreases, if acidosis (acidification of the blood by metabolic products), then, on the contrary, it increases.

Absorption of electrolytes and water

Electrolytes are salt solutions and metal ions that can conduct electricity.

electrolytes

Electrolytes include calcium ions, phosphates, sodium, water molecules. Each substance plays a huge role in the functioning of the heart, nervous system and skin.

Absorption of calcium and phosphate occurs almost entirely in the renal tubules and is regulated by a number of hormones such as parathyroid hormone, calcitonin, and calcitriol.

The absorption of sodium from the primary urine is equally important for the functioning of the body. This process also occurs with the expenditure of energy under the action of the hormone aldosterone and its opposite, natriuretic hormone.

Reabsorption of water occurs passively and occurs together with sodium ions. It is regulated by the hormone vasopressin (antidiuretic hormone), which is produced in the hypothalamus.

Glucose absorption

The kidneys, like the liver, make a huge contribution to the regulation of carbohydrate metabolism. The basis for these chemical reactions is the energy supply of this process, which is also associated with sodium transport.

endocrine function of the kidneys

In addition to the function of removing end products of metabolism, the kidneys play the role of endocrine glands. The kidneys are the site of production of hormones such as erythropoietin, calcitriol, and renin.

As I wrote above, erythropoietin is a stimulator of the division of the pluripotent stem cell of the red bone marrow, which gives rise to all red blood cells. In this case, impaired renal function may be the cause of anemia.

Renin is a hormone that is involved in the renin-angiotensin system of regulation of vascular tone, and at the same time in maintaining a constant value of blood pressure.

With aging, kidney function tends to decline permanently. This is due to ischemia, which progresses over time, leading to a decrease in effective renal blood flow and glomerular filtration.

As you have already noticed, the kidneys are a vital organ for every person. Therefore, if you begin to suspect about any pathology, you should immediately consult a doctor.