The structure of the human internal organs of the kidney. The structure of the kidneys and their role in the functionality of the body. How is urination

The human kidney, along with the ureter, urethra and bladder belong to the urinary organs. Since the violation of their functions leads to a number of diseases, one should be careful not to allow them to become infected.

Human kidneys: location and structure

These bean-shaped organs are paired. They are located in the retroperitoneal cavity on both sides of the spine in lumbar. The mass of each of them is about 150 g. The size of a human kidney does not exceed 12 cm in length. From above, the organ is covered with a dense membrane. Its inner side is concave. Through it pass veins, arteries, ureter, nerves and lymphatic vessels. If you cut the organ lengthwise, you can see that its tissue has outer layer(it is darker) - the cortical substance and the medulla, this the inner layer. It also has a void - the renal pelvis. Gradually, it passes into the ureter. Under a microscope, you can see that the human kidneys consist of a huge number of complex formations - nephrons. There are about a million of them. Initial department Each nephron consists of a vascular glomerulus surrounded by a goblet capsule. A sinuous tubule of the first order departs from it. It looks like a long and thin tube and reaches where the cortex and medulla end. In the latter, the tubule forms a nephron loop. From there it returns to the cortex. Here the tubule becomes tortuous again (tubule of the second order). It opens into a collecting duct. There are several of them. Merging into one, the collecting ducts form ducts that open into the renal pelvis. Both the walls of the tubules and the walls of both capsules have one common layer of epithelial cells. At the entrance to the organ, the renal artery branches strongly into the thinnest vessels - capillaries. They are collected in small veins, which, when connected together, form one renal vein. It carries blood out of the body.

human kidney: participation in the formation of urine

The body constantly receives a large number of blood. Due to complex processes of filtration, and then reabsorption, urine is formed from it. Cleansing takes place in capsules. Blood plasma, together with all the substances that are dissolved in it, enters their voids under high pressure. Only those that have smaller molecules are filtered. As a result of this process, primary urine is formed in the voids of the renal capsules. It consists of uric acid, urea and all components of blood plasma, with the exception of proteins. For a day, it is formed in a person from 150 to 170 liters. Next, the primary urine is sent to the tubules. Its walls are lined with epithelial cells. They absorb a lot of water and needed by the body substances from primary urine. This process is called reabsorption. After that, secondary urine is formed. If the kidneys are working normally, there is no glucose and protein in it. On average, it turns out up to 1.5 liters per day.

human kidney: their role in maintaining water-salt homeostasis

The functions of this organ are not limited to the release of residual products as a result of metabolism. Also, the kidneys are actively involved in the regulation of water-salt balance and in maintaining the stability of the osmotic pressure of body fluids. Depending on the content mineral salts in the blood and in the tissues they excrete more or less concentrated urine. This process is regulated by humoral substances and nervous system. With an increase in the concentration of salts in the blood, irritation of those receptors that are located in the blood vessels occurs. Excitation from them enters the center of urination in the diencephalon and the pituitary gland, having received a signal, releases antidiuretic hormone. It enhances the absorption of water in the tubules. As a result, urine becomes more concentrated and excess salts leave the body with it. If there is too much water in it, the pituitary gland secretes a smaller amount of the hormone. As a result, absorption decreases, and excess water is excreted in the urine.

The kidneys are paired organ, which is responsible for the excretion of the remains of human waste products from the body. The anatomy of the kidneys has the following location - this organ is attached to the sides of the spine at the level of the two upper lumbar vertebrae, and, as a rule, right kidney fixed slightly lower than the left, on average, about one and a half centimeters.

The structure and location of the kidneys

This arrangement exposes the right kidney most at risk diseases. This paired organ has a bean-shaped shape, the approximate weight of each of them is approximately one hundred and fifty grams.

Outside, each kidney is covered with a sheath of fatty and connective tissue, but each of them has two layers. The first layer of a dark color is called the cortical, the second layer is lighter, in other words, this is the medulla of the kidney. The medulla of the kidney contains renal tubules, and cortical - capsules of nephrons.

Developmental pathology

Like other organs inside a person, the kidneys grow with the body. But there are also pathological abnormalities, due to which failures occur, they can be caused various factors. In the process of such a failure, the kidneys can grow either too large or too small.

If a person has the correct structure of the kidney, then they function normally, without causing any problems, but if the size of at least one of the kidneys is outside the norm, this can negatively affect its functionality and cause health problems.

Usually, it is considered normal for an adult if the kidney is about thirteen centimeters long, seven centimeters wide, and about two and a half centimeters thick. If we compare the kidney with the surrounding objects, then it is the size of a fist or a standard computer mouse. As for the norm for children, it is difficult to indicate specific data, since each child develops individually.

It should be remembered that every function that the kidneys perform is extremely important for the human body, if for any reason a malfunction occurs, this can lead to very sad consequences up to death. Therefore, in order to avoid such an outcome, you need to be more careful about your health and, if there is the slightest suspicion, immediately seek medical help.

Many specialists base their treatment on medicinal herbs and Special attention give bearberry leaves, which have a positive effect on the human body. As a rule, this plant helps to fight not only with inflammatory processes but also helps relieve pain.

Despite such effective impact, which is provided medicinal herbs, take them yourself and set dosages without consulting a doctor is not worth it, since a single herb may have a number of contraindications.

Diet foods

Also, a diet based on the intake of vegetables and fruits, with a limited intake, is considered no less effective. table salt and spices. The main harm in the treatment is caused by tobacco and alcohol. If a person’s kidneys are already in a neglected form, then taking infusions from birch buds and corn silk. Such an infusion is drunk in half a glass about five times a day.

Traditional medicine advises people who are not all right with their kidneys to use potatoes in their “uniforms” more often, the use of one hundred grams of dried apricots has a beneficial effect on chronic diseases and swelling, but sand and small stones are removed by ordinary oats. Pumpkin restores the body's metabolism, which is why it is so necessary in the patient's diet.

Preventive measures

Lifestyle

No matter how trite it may sound, but one of the main preventive measures is a healthy lifestyle. You should try to drink at least two liters of water a day, because drinking enough water helps to leave the body along with the urine of pathogens. But you should know the measure in the use of daily water intake, if the patient has any pathologies associated with the kidneys. Stop drinking alcohol and alcoholic beverages, replacing them green tea and clean water.

The best auxiliary effect comes from the use of fresh fruits and vegetables, during the ripening of watermelons, you should try to buy as many of them as possible. It is watermelons that perfectly wash the kidneys, which has a very positive effect on their performance.

This steamy body does not like sedentary image life, so you need to engage in non-heavy physical activity and do necessary exercises. At work, as often as possible, you need to take short breaks and perform slopes. If it is not possible to do fitness in the evenings, then you can do housework, which is associated with light physical labor.

Periodic trips to saunas or baths can also give a very good result, since during the steaming process, harmful substances come out with sweat, thereby unloading the organ itself and giving it a rest.

Thanks to the observance of such simple preventive appointments, in the future you can save yourself from possible diseases and unpleasant complications. You should not focus on only one organ, you should monitor your health completely.

Human kidneys are paired organs of the urinary system, which have amazing performance, since the process of purification and excretion harmful substances continues indefinitely.

human kidney

Thanks to the research, you can be absolutely sure that the anatomy of the human kidneys has been studied

thoroughly.

These paired organs are located symmetrically to each other relative to the spine. Only in the human body it is slightly smaller and is located below the left, since the liver is located above it.

The human kidney is a bean-shaped organ. External surface human kidney is dense and smooth, it is covered with a fibrous capsule, which is a thin but very strong film of connective tissue.

In addition, both kidneys are enclosed in a fatty membrane, thanks to which they can be kept in the human body in one place, which anatomy has predetermined for them.

The kidney tissue, called the parenchyma, is two-layered. The internal structure of the kidney is quite complex, the parenchyma acts as the main filtering tool, and the pelvis is the mechanism that removes harmful substances.

The renal pelvis is formed from the small and large calyces of the kidneys.

From the pelvis comes the ureter, which connects it to the bladder and ensures the excretion of urine through it.

The nephron is the structural unit of the human kidney structure, in other words, it is the main filtering element. The nephron is made up of renal tubules and corpuscles.

The tubules of the human kidneys outwardly resemble a ball of blood vessels, surrounded on all sides by a capsule. It is in it that filtration of blood plasma occurs under a certain pressure.

The liquid formed during this filtration is the primary urine.

Primary urine is not excreted outside, but is directed through long tubules, heading into the collecting duct. In the process of moving through the canals useful material(water and electrolytes) are absorbed, and the remaining liquid is discharged to the outside.

It is she who is the secondary urine, which enters the calyces of the kidneys, then into the pelvis, then into the ureter and finally excreted from the human body.

Tasks of the body

Understanding what the kidneys look like, and realizing that there are several people, it is easy to understand how important this organ is for the full life of a person. The filtering and excretory function is main function, which nature endowed the kidneys with.

But in addition to these tasks, the kidney organs perform several other important functions. In particular, compliance water-salt balance and in the body, which is important for human life.

And it is the kidneys that keep track of such an important ratio, since with sharp increase salts, dehydration occurs in the cells, and when the natural level of salts decreases, on the contrary, an excessive amount of water is concentrated in them, which provokes swelling.

Kidney Functions

Therefore, the osmoregulatory function of the kidneys, which occurs in the body, is just as important and necessary as the excretory one.

The ion-regulating function is also aimed at regulating the ratio, but only the acid-base ratio. Anatomy predetermines the release of excess amounts of hydrogen ions or bicarbonate ions.

The metabolic processes taking place in the human body are also of great importance. The kidney organs also perform metabolic functions, due to which harmful toxins, drug residues, proteins are removed.

The endocrine function performs the tasks of producing substances that regulate blood pressure, as well as hormones from the adrenal glands. Red blood cells are formed in the body only through endocrine function.

Causes and symptoms of diseases

Kidney diseases are pathologies that provoke malfunctions in the functioning of the organ, as well as leading to serious injuries kidney tissues. As a result of such pathologies, the functions of the kidneys in the human body are noticeably impaired.

kidney cancer

Most often negative impact All kinds of bacteria and infections affect the performance of organs. It is they who can provoke stagnation of urine of varying duration, which, after its manifestation, entails more serious problems.

The anatomy of the renal organs can be disturbed due to the formation of cysts and tumors of various etymologies in them.

Metabolic disorders adversely affect many internal processes, kidneys are no exception. As a result of a decrease in the efficiency of the parenchyma, renal diseases occur.

Pathologies can also be congenital in nature, patients have various anomalies in the internal structure of the organ itself or in the inadequate performance of the intended functions.

The formation of stones in the kidney organs is also the cause of serious disorders in their functioning.

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Any pathology can be detected initially by the patient himself. Symptoms are conditionally divided into general and characteristic.

General symptoms should alert the patient and "direct" to medical institution for examination, since such symptoms can only suggest the presence of renal pathology.

But the same symptoms can be accompanied by other diseases. To common features include fever, chills, fatigue, increased blood pressure.

The characteristic symptoms include those that are characteristic only of the kidneys. Increased swelling, polyuria, oliguria, cramps and burning during urination are all signs that indicate obvious problems with the urinary system.

Another characteristic symptom is a change in the color of urine.

If at a certain stage an altered anatomy of the kidneys was found, accompanied by characteristic symptoms pathologies, it is important to start treatment immediately to prevent a decrease in their functioning or complex diseases their total loss.

Pathologies

The kidneys of any person can be exposed to many diseases that need to be treated. emergency treatment. Such diseases can be acquired due to non-compliance healthy lifestyle life, fundamentals proper nutrition and also hereditary.

Any disease of the kidney organs turns into chronic stage if the necessary treatment is not carried out.

Glomerulonephritis

Glomerulonephritis- this is inflammatory disease, which is accompanied by damage to the glomeruli and tubules of the kidneys. The culprits of this complex pathology in most cases are streptococci.

Although medicine knows cases when glomerulonephritis occurred against the background of tuberculosis or malaria. Treatment of glomerulonephritis is long and scrupulous.

Pyelonephritis- another inflammatory disease, the anatomy of which is the defeat of the parenchyma, calyces and pelvis of the kidneys. Streptococcus, staphylococcus, Escherichia coli provoke such a pathology.

The basis for the occurrence of such a pathology is a violation of the outflow of urine.

Treatment of pyelonephritis is accompanied by the use of antibiotics, as well as medicines to strengthen defensive forces organism.

Nephroptosis consists in the depletion of the fatty capsule, as a result of which the kidney passes into the category of wandering, since there is nothing more to keep it in one place.

Treatment involves the normalization of nutrition, wearing a special bandage to hold the kidney in an anatomical place. A complete treatment should be accompanied by the implementation of a complex of physiotherapy exercises.

Urolithiasis is characterized by the formation of stones in the kidneys that differ in their chemical composition. Treatment of such a pathology is taking drugs that help dissolve stones and bring them out.

In some cases, surgery is necessary.

Hydronephrosis is characterized by the expansion of the cavities of the kidneys due to stagnation of urine. Treatment, first of all, is aimed at eliminating the root cause.

kidney failure- the most serious pathology, since it can lead to lethal outcome. Therefore, it is important to start complete treatment to prevent such consequences.

The human kidney is the main component genitourinary system person. The structure of the human kidney and the physiology of the kidneys are quite complex and specific, but it is they that allow these organs to perform vital functions. important features and have a huge impact on the homeostasis of all other organs in the human body.

A little about the origin

During their development, the kidneys go through three stages: pronephros, mesonephros and metanephros. Pronephros is a kind of pronephros, which is a rudiment that does not function in a person. There are no glomeruli in it, and the tubules are not connected with blood vessels. The pronephros is completely reduced in the fetus at 4 weeks of development. At the same time, at 3-4 weeks, the embryo is laid primary kidney, or mesonephros - the main excretory organ of the fetus in the first half prenatal development. It already has glomeruli and tubules that connect to two pairs of ducts: the Wolffian duct and the Müllerian duct, which in the future give rise to the male and female genital organs. The mesonephros is actively functioning in the fetus somewhere up to 4-5 months of development.

The final kidney, or metanephros, is laid in the fetus at 1–2 months, is fully formed at the 4th month of development, and subsequently works as the main excretory organ.

Topography

There are two kidneys in the human body. These organs are located behind the peritoneum on both sides of the ridge. Their shapes are a bit like beans. The height of their projection on the lower back in both an adult and a child corresponds to 11 and 12 thoracic vertebrae and 1 and 2 lumbar, but the right one, due to its position close to the liver, is placed slightly lower than the left. In these organs, two surfaces are described - posterior and anterior, two edges - median and lateral, two poles - lower and upper. The upper poles are placed a little closer one to one than the lower ones, since they are somewhat inclined towards the spine.

On the median edge there is a gate - the zone that the ureter and renal vein leave and where the renal artery enters. In addition to the liver, the right kidney is in close proximity to part colon front and cut duodenum along its median edge. The jejunum and stomach, together with the pancreas, are adjacent to the left along its anterior surface, and the spleen, together with a fragment of the large intestine, along its lateral edge. At the top, above each pole, is the adrenal gland, or adrenal gland.

Where and how are the kidneys attached?

Elements of the fixing apparatus - it is they that allow both organs to stay in one place and not wander throughout the body. The fixing apparatus is formed from the following structures:

• vascular legs;
• ligaments: hepatic-renal with duodenal-renal - on the right and diaphragmatic-colon - on the left;
• own fascia, connecting the organs with the diaphragm;
• fatty capsule;
• renal bed formed by the muscles of the back and abdomen.

Protection: renal membranes

Both bodies are outside covered with a fibrous capsule, which is formed by elastic fibers and smooth muscle cells. From this capsule, interlobular layers of connective tissue extend inward. Outside, a fatty or adipose renal capsule is adjacent to the fibrous capsule, providing reliable protection organ. This capsule becomes somewhat denser on the posterior renal surface and forms the perirenal adipose body. Above the adipose capsule is placed the fascia of the kidneys, formed by two sheets: prerenal and retrorenal. They are tightly woven together at the upper poles and lateral edges, but from below they do not grow together. Some of the fascia fibers pierce the fatty capsule of the kidney, intertwining with the fibrous one. The shells of the kidney provide protection.

kidney structure

The cortex of the kidney and the medulla - they form internal structure kidneys. The outer cortical layer is bordered by a fibrous capsule. Its part called "renal columns" penetrates the medulla of the kidney, dividing it into certain parts - pyramids. They are similar in shape to a cone and, together with adjacent pillars, form the renal lobe. In several pieces, they are assembled into segments: upper segment, upper front, rear, lower front and lower. Pyramidal tops form papillae with holes. They are collected in a small renal calyx, from which large renal calyces are further formed. Each large cup, or calyx, merges with the others to form a pelvis, whose shape resembles a watering can. Its walls are built from the outer shell, muscular and mucosal, which is formed by the transitional epithelium and basement membrane. The pelvis of the kidney gradually narrows and merges into the ureter at the gate.

This anatomy of the kidneys is of key importance for the implementation of their functions.

Renal nephrons

The structural and functional unit in the kidney is called the nephron. It is formed by two components: the renal corpuscle of Malpighi and the tubular countercurrent-turning complex. The compressed structure of the nephron looks like this: a body created by a glomerulus of vessels with an external capsule of Shumlyansky-Bowman, next comes the proximal convoluted tubule, then the proximal rectus tubule, then the loop of the nephron, known as the loop of Henle, followed by the distal convoluted tubule. Several distal canals form the collecting ducts, which unite to form the collecting duct. They form the papillary ducts, leaving the opening on the papillae.

Millions of nephrons form both substances of the organ: the cortical, or outer layer of the kidneys is formed by the body and the complex of convoluted tubules, the rest of the countercurrent system forms medulla with its pyramids. Also, each of these organs has its own small endocrine apparatus, known as the JUGA (juxtaglomerular apparatus). It synthesizes the hormone renin and is formed from several types of cells: juxtaglomerular cells, mesangial cells, juxtavascular cells, and macula densa. From 1500 to 1800 liters of blood passes through the kidneys per day.

Renal circulation provides complete renal arteries and veins. The artery gives rise to the posterior and anterior branches. From the anterior segmental arteries branch off, which feed the segments of the kidney. Accompanying the pyramids, the interlobar arteries follow, followed by the arcuate arteries between both layers, then the interlobular or radial cortical arteries, the branches of which also supply the fibrous capsule. In addition, the interlobular arteries extend even into the afferent glomerular arterioles that form the glomerulus of the body. The efferent glomerular arteriole originates from the latter.

All efferent arterioles form a network of capillaries. The capillaries are further combined into venules that form the interlobular or radial cortical veins. They unite with the arcuate veins, then the interlobar veins follow, merging into the renal one, leaving the renal gate. Accordingly, blood enters the kidneys through the arteries, and leaves them through the veins. Thanks to vascular system the kidneys are arranged in such a way that they carry out their main functions.

Renal lymph flow

The renal lymphatic vessels are arranged in such a way that they follow next to the blood vessels. Among them are deep and superficial. The lymphocapillary networks of the renal membranes form superficial vessels, while the deep ones originate in the interlobar subspace. There are no lymphocapillaries and vessels in the lobules and renal corpuscles. In the zone of the gate, deep vessels merge with superficial ones, and then enter the lumbar lymph nodes.

The kidney is a unique organ human body, which cleanses the blood of harmful substances and is responsible for the excretion of urine.

According to its structure, the human kidney belongs to complex paired internal organs who play important role in the life support of the organism.

Organ Anatomy

The kidneys are located in the lumbar region, to the right and left of the spine. They can be easily found if you put your hands on your waist and stretch out thumbs up. The desired organs will be located on the line connecting the tips of the thumbs.

Average kidney size represent the following picture:

• Length - 11.5-12.5 cm;
• Width - 5-6 cm;
• Thickness - 3-4 cm;
• Weight - 120-200 g.

Development is influenced by its proximity to the liver. The liver does not allow it to grow and shifts down.

This kidney is always slightly smaller than the left and is located just below its paired organ.

The shape of the kidney resembles a large bean. On its concave side there is a "renal gate", behind which lie the renal sinus, pelvis, large and small bowls, the beginning of the ureter, the fatty layer, the plexus of blood vessels and nerve endings.

From above, the kidney is protected by a capsule of dense connective tissue, under which there is a cortical layer. 40 mm deep. The deep zones of the organ consist of the Malpighian pyramids and the renal columns separating them.

The pyramids consist of many urinary tubules and parallel vessels, which make them appear striated. The pyramids are deployed with their bases to the surface of the organ, and their tops - to the sinus.

Their tops are combined into papillae, several pieces in each. The papillae have many small holes through which urine seeps into the cups. Urine collection system consists of 6-12 small cups, forming 2-4 larger bowls. The bowls, in turn, form the renal pelvis connected to the ureter.

The structure of the kidney at the microscopic level

The kidneys are from microscopic nephrons associated both with individual blood vessels and with the entire circulatory system generally. Thanks to a huge number nephrons in the organ (about a million), its surface involved in the formation of urine reaches 5-6 sq.m.

(Image is clickable, click to enlarge)

The nephron is penetrated by a system of tubules, the length of which reaches 55 mm. The length of all renal tubules is approximately 100-160 km. AT nephron structure includes the following elements:

• Shumlyansky-Boumea capsule with a tangle of 50-60 capillaries;
• tortuous proximal tubule;
• loop of Henle;
• a tortuous distal tubule connected to the collecting duct of the pyramid.

The thin walls of the nephron are formed from a single-layered epithelium, through which water easily seeps. Shumlyansky-Bowman's capsule is located in the cortical layer of the nephron. Its inner layer is formed by podocytes - large stellate epithelial cells located around the renal glomerulus.

From the branches of podocytes, pedicles are formed, the structures of which create a lattice-like diaphragm in the nephrons.

Loop of Gengle It is formed by a convoluted tubule of the first order, which begins in the Shumlyansky-Bowman capsule, passes through the medulla of the nephron, and then bends and returns back to the cortical layer, forms a convoluted tubule of the second order and merges with the collecting duct.

The collecting ducts connect into larger ducts and reach the tops of the pyramids through the thickness of the medulla.

Blood is supplied to the renal capsules and capillary glomeruli through standard arterioles, and is discharged through narrower efferent vessels. The difference in the diameters of the arterioles creates a pressure in the glomerulus of 70-80 mmHg.

Under the action of pressure, part of the plasma is squeezed out into the capsule. As a result, such glomerular filtration»primary urine is formed. The composition of the filtrate differs from the composition of plasma: it does not contain proteins, but there are decay products in the form of creatine, uric acid, urea, as well as glucose and useful amino acids.

Nephrons depending on location subdivided into:

• cortical,
• juxtamedullary,
• subcapsular.

The nephrons are unable to regenerate.

Therefore, under the influence adverse factors a person may develop kidney failure - a condition in which the excretory function of the kidneys will be partially or completely impaired. Kidney failure can lead to serious violations homeostasis in the human body.

What functions does it perform?

The kidneys perform following features:

• excretory;

The kidneys successfully excrete from the human body excess water with decay products. Every minute, 1000 ml of blood is pumped through them, which is freed from microbes, toxins and toxins. Decay products are excreted from the body naturally.

• osmoregulatory;

The kidneys, regardless of the water regime, maintain a stable level of osmotic active substances in blood. If a person is thirsty, the kidneys excrete osmotically concentrated urine, if his body is oversaturated with water - hyotonic urine.

• ion-regulating;

The kidneys provide acid-base and water-salt balance of extracellular fluids. This balance is achieved both due to its own cells and due to the synthesis of active substances. For example, due to acidogenesis and ammonigenesis, H+ ions are removed from the body, and parathyroid hormone activates the reabsorption of Ca2+ ions.

• endocrine;

The kidneys synthesize the hormones erythropoietin, renin and prostaglandins. Erythropoietin activates the production of red blood cells in bone marrow. Renin is involved in regulating the volume of blood in the body. Prostaglandins regulate blood pressure.

• metabolic;

The kidneys are the site of the synthesis of substances necessary for the maintenance of the body. For example, vitamin D is converted here to its more active fat-soluble form, cholecalciferol (D3).

In addition, these paired urinary organs contribute to achieving a balance between fats, proteins and carbohydrates in body fluids.

• participate in the formation of blood.

The kidneys are involved in the creation of new blood cells. These organs produce the hormone erythropoietin, which promotes hematopoiesis and the formation of red blood cells.

Features of the blood supply

Pushes through the kidneys in a day from 1.5 to 1.7 thousand liters of blood.

No one has such a powerful blood flow human organ. Each kidney is equipped with a pressure stabilization system that does not change during periods of increase or decrease in blood pressure throughout the body.

(Image is clickable, click to enlarge)

The renal circulation is represented two circles: large (cortical) and small (justomedullary).

big circle

Vessels of this circle nourish the cortical structures of the kidneys. They start with major artery that originates from the aorta. Immediately at the gate of the organ, the artery is divided into smaller segmental and interlobar vessels, penetrating the entire body of the kidney, starting from the central part, ending with the poles.

The interlobar arteries lie between the pyramids and, reaching the border zone between the medulla and cortex, are connected to the arcuate arteries penetrating the thickness of the cortical substance parallel to the surface of the organ.

Short branches of the interlobar arteries (see photo above) penetrate the capsule and disintegrate into a capillary network that forms a vascular glomerulus.

After that, the capillaries recombine and form narrower efferent arterioles, in which high blood pressure necessary for the passage of plasma compounds into the renal canals. It flows here the first stage of urine formation.

small circle

This circle consists of excretory vessels, which form a dense capillary network outside the glomeruli, braiding and feeding the walls of the urinary tubules. Here, arterial capillaries are transformed into venous ones and give rise to excretory venous system organ.

From the cortex, oxygen-depleted blood sequentially enters the stellate, arcuate, and interlobar veins. The interlobar veins form the renal vein, which drains blood from the hilum of the organ.

How our kidneys work- watch the video: