Anatomy of the right kidney. The structure, function and blood supply of the human kidneys. The internal structure of the kidney

1. Watch the movie "Excretory System. Kidneys"

YouTube video

2. Read the text and write down the functions of the kidneys in a notebook

kidneys- main and most important paired organ urinary system person. The kidneys are bean-shaped, 10-12 x 4-5 cm in size and are located in the retroperitoneal space on the sides of the spine. The right kidney is crossed by the line of the right 12th rib in half, while 1/3 of the left kidney is above the line of the left 12th rib, and 2/3 is below (that is, the right kidney is located slightly below the left). On inspiration and when a person moves from horizontal to vertical position the kidneys are displaced downward by 3-5 cm. The fixation of the kidneys in the normal position is ensured by ligamentous apparatus and the supporting effect of perirenal fiber. The lower pole of the kidneys can be felt by hand on inspiration in the right and left hypochondria.

The main functions of the kidneys are:

• in regulation water-salt balance body (maintaining the necessary concentrations of salts and the volume of fluid in the body);
• in the removal of unnecessary and harmful (toxic) substances from the body;
• in regulation blood pressure.

The kidney, filtering the blood, produces urine, which is collected in the abdominal system and excreted through the ureters into the bladder and further out. Normally, all the blood circulating in the body passes through the kidneys in about 3 minutes. Per minute, 70-100 ml of primary urine is filtered in the renal glomeruli, which subsequently concentrates in the renal tubules, and per day an adult eventually excretes an average of 1-1.5 liters of urine (300-500 ml less than he drank) . The cavitary system of the kidney consists of the calyces and the pelvis. There are three main groups of kidney cups: upper, middle and lower. The main groups of cups, connecting, form the renal pelvis, which then continues into the ureter. Promotion of urine is provided by peristaltic (rhythmic wave-like) contractions of the muscle fibers of the walls of the renal calyces and pelvis. Inner surface cavity system The kidneys are lined with a mucous membrane (transitional epithelium). Violation of the outflow of urine from the kidney (stone or narrowing of the ureter, vesicoureteral reflux, ureterocele) leads to increased pressure and expansion of the abdominal system. A long-term violation of the outflow of urine from the cavitary system of the kidney can cause damage to its tissue and serious violation its functions. Most frequent illnesses kidneys are: bacterial inflammation kidneys (pyelonephritis), urolithiasis, tumors of the kidney and renal pelvis, congenital and acquired anomalies in the structure of the kidney, leading to impaired outflow of urine from the kidney (hydrocalicosis, hydronephrosis). Other kidney diseases are glomerulonephritis, polycystic disease, and amyloidosis. Many kidney diseases can lead to high blood pressure. Most severe complication kidney disease is kidney failure, which requires the use of the device artificial kidney or a donor kidney transplant.

3. Draw the structure of the kidney in a notebook

The kidneys are a paired organ that is part of the urine. excretory system. If the main function is known to most people, then the question of where the kidneys are in a person can be confusing for many. But despite this, the function of the kidneys in the body is extremely important.

The structure of the kidneys and their role in the functionality of the body

Normally, in humans, the kidneys are a paired organ (only 1 or 3 are possible). They are located on the sides of the spine at a level between the last thoracic and 2-3 lumbar vertebrae. Pressure right lobe liver explains the difference in elevation: left kidney normally located 1-1.5 centimeters above the second paired organ. The normal location of the kidneys in a person also depends on his gender: in women, the main organs of the excretory system are half a vertebra below.

The upper and lower points on the organ are called poles. The distance between the upper poles of the kidneys is about 8 cm, between the lower ones - up to 11 cm. The location of the kidneys in the human body may be abnormal, as natural causes as well as due to lack of weight or excessive load(omission).

It is easy to imagine what the kidneys look like: the shape of paired organs resembles a bean weighing no more than 120-200 grams. Their width is 10-12 centimeters, the length is half as much, and the thickness varies between 3.8-4.2 cm. Each of the kidneys is divided into lobes (kidney segments) and placed in a capsule of connective tissue and layers of fat (perirenal fiber). In the depths there is a layer of smooth muscles and directly the working body of the organ. The protective shells of the kidney provide the system with stationarity, protect it from shocks and shocks.

The structural functional unit of the kidney is the nephron. With its participation, filtration and reabsorption occurs in the kidneys.

The nephron includes the so-called. the renal corpuscle and various tubules (proximal, loop of Henle, etc.), as well as the collecting ducts and the juxtaglomerular apparatus responsible for renin synthesis. Total functional units can be up to 1 million.

The structure of the kidney

The renal glomerulus and the Bowman-Shumlyansky capsule surrounding it make up the so-called nephron body, from which the canals depart. Its main task is ultrafiltration, i.e. separation of liquid and low molecular weight substances and the formation of primary urine, the composition of which is almost identical to blood plasma. The function of the tubules is to reabsorb primary urine back into the bloodstream. At the same time, decay products of nutrients, excess glucose and other substances that are then present in the composition of concentrated urine remain on their walls.

The tubules of the nephrons, extending from the renal corpuscle, pass simultaneously into the cortical and so-called. renal medulla. The cortical layer is external to the center of the organ. If you make a transverse section of the organ, it will be seen that the cortical substance human kidney mainly contains the glomeruli of nephrons, and the brain - tubules extending from them. However, the topography of the kidneys mostly does not depict such a large scale.

The medulla of the kidney forms pyramids, the base facing the outer layer. The tops of the pyramids go into the cavity of the small calyces of the kidney and are in the form of papillae that unite the tubules of the nephrons, through which concentrated urine is excreted. 2-3 small renal calyces form a large renal calyx, and a combination of large ones forms a pelvis.

Finally, the renal pelvis passes into the ureter. Two ureters transport concentrated liquid waste to the bladder. Paired organs communicate with the body through arteries and veins. The collection of vessels entering the deepening of the kidney is called - this is the renal pedicle.

In addition to the medulla and cortical layer, the excretory organ is also made up of the renal sinus, which is a small space in which the cups, pelvis, fiber, feeding vessels and nerves are located, and the gate of the kidney, in which the lymph nodes of the pelvis lie, through which the blood and lymphatic vessels as well as nerves. The gates of the organ are located on the side of the spine.

The role of the kidneys and their functions

If you study what function the kidneys perform in the body, it will become clear the importance of their role in the overall life of a person. This organ cannot be considered exclusively as an excretory one, because. in addition to the excretion of end products of metabolism, the task of the kidneys includes:

Despite the versatility of the organ, the main defining function of the kidneys is cleansing bloodstream and removal of decay products, excess fluid, salts, and other substances from the body.

The main work of the kidneys

The work of the kidneys, in fact, is a repeated distillation of blood. The process is carried out in this way:

In folk medicine of the East, the functions of the paired excretory organ are tied to the concept of energy. The kidney meridian identifies possible violations ion exchange, excretory and secretory functions.

The most common kidney pathology

The physiology of the kidneys (their performance of their functions) depends on the internal (structural) and external factors(fluid intake, drug load, etc.). Most frequent violations The functions of the kidneys are:

Most of the diseases can be avoided with the help of a balanced diet, compliance with the water regime (at least 2 liters of water per day), prevention urolithiasis with herbal infusions timely treatment systemic diseases avoidance of heavy physical exertion and hypothermia. The structure and functions of the human kidneys make it possible to ensure the normal functioning of the body, subject to the regimen and maintaining the health of the whole body.

(Fig. 1). They are bean-shaped and located in the retroperitoneal space on inner surface posterior abdominal wall on either side of spinal column. Weight of each kidney an adult is about 150 g, and its size roughly corresponds to a clenched fist. Outside, the kidney is covered with a dense connective tissue capsule that protects the delicate internal structures organ. Enters the gate of the kidney renal artery, the renal vein, lymphatic vessels and the ureter emerge from them, originating from the pelvis and removing the final urine from it into the bladder. On a longitudinal section in the tissue of the kidney, two layers are clearly distinguished.

Rice. 1. Structure of the urinary system: words: kidney and ureters (paired organs), bladder, urethra (indicating the microscopic structure of their walls; SMC - smooth muscle cells). As part of right kidney shows the renal pelvis (1), the medulla (2) with pyramids opening into the cups of the cups of the pelvis; cortical substance of the kidneys (3); right: main functional elements of the nephron; A - juxtamedullary nephron; B - cortical (intracortical) nephron; 1 - renal body; 2 - proximal convoluted tubule; 3 — a loop of Henle (consisting of three departments: a thin descending part; a thin ascending part; a thick ascending part); 4 — a dense spot of a distal tubule; 5 - distal convoluted tubule; 6 connecting tubule; 7-collective duct of the medulla of the kidney.

outer layer, or cortical gray-red substance, kidneys has a granular appearance, as it is formed by numerous microscopic structures of red color - renal corpuscles. The inner layer, or medulla, kidneys consists of 15-16 renal pyramids, the tops of which (renal papillae) open into small renal calyces (large calyces of the pelvis). In the medulla, the kidneys secrete the outer and inner medulla. The kidney parenchyma is made up of renal tubules, and stroma - thin layers of connective tissue in which the vessels and nerves of the kidneys pass. The walls of the cups, cups, pelvis and ureters have contractile elements that help move urine into the bladder, where it accumulates until it is emptied.

The value of the kidneys in the human body

The kidneys perform a number of homeostatic functions, and the idea of ​​them only as an organ of excretion does not reflect their true significance.

To kidney function their involvement in the regulation

• volume of blood and other fluids internal environment;
• constancy osmotic pressure blood;
• constancy of the ionic composition of the liquids of the internal environment and the ionic balance of the body;
• acid-base balance;
• excretion (excretion) of end products nitrogen metabolism(urea) and foreign substances (antibiotics);
• excretion of excess organic substances received with food or formed during metabolism (glucose, amino acids);
• blood pressure;
• blood clotting;
• stimulation of the process of formation of red blood cells (erythropoiesis);
• secretion of enzymes and biologically active substances(renin, bradykinin, urokinase)
• metabolism of proteins, lipids and carbohydrates.

Kidney Functions

The functions of the kidneys are diverse and important for the life of the body.

Excretory (excretory) function- the main and most well-known function of the kidneys. It consists in the formation of urine and the removal with it from the body of metabolic products of proteins (urea, ammonium salts, creaginine, sulfuric and phosphoric acids), nucleic acids ( uric acid); excess water, salts, nutrients (micro and macro elements, vitamins, glucose); hormones and their metabolites; medicinal and other exogenous substances.

However, in addition to excretion, the kidneys perform a number of other important (non-excretory) functions in the body.

homeostatic function kidney is closely related to the excretory and is to maintain the constancy of the composition and properties of the internal environment of the body - homeostasis. The kidneys are involved in the regulation of water and electrolyte balance. They maintain an approximate balance between the amount of many substances excreted from the body and their entry into the body, or between the amount of the resulting metabolite and its excretion (for example, water in and out of the body; incoming and outgoing electrolytes of sodium, potassium, chlorine, phosphates, etc.) . Thus, the body maintains water, ionic and osmotic homeostasis, a state of isovolumy (relative constancy of the volumes of circulating blood, extracellular and intracellular fluid).

By excreting acidic or basic foods and regulating the buffer capacities of body fluids, the kidneys, along with respiratory system provide maintenance of the acid-base state and isohydria. The kidneys are the only organ that secretes sulfuric and phosphoric acids, which are formed during protein metabolism.

Participation in the regulation of systemic blood pressure - The kidneys play the main role in the mechanisms of long-term regulation of blood pressure through changes in the excretion of water and sodium chloride from the body. Through the synthesis and secretion of various amounts of renin and other factors (prostaglandins, bradykinin), the kidneys are involved in the mechanisms of rapid regulation of blood pressure.

Endocrine function of the kidneys - this is their ability to synthesize and release into the blood a number of biologically active substances necessary for the life of the body.

With a decrease in renal blood flow and hyponatremia, renin is formed in the kidneys - an enzyme, under the action of which the angiotensin I peptide, a precursor of the powerful vasoconstrictor substance angiotensin II, is cleaved from the a 2 -globulin (angiotensinogen) of the blood plasma.

In the kidneys, bradykinin and prostaglandins (A 2 , E 2) are formed, which dilate blood vessels and lower blood pressure, the enzyme urokinase, which is an important part of the fibrinolytic system. It activates plasminogen, which causes fibrinolysis.

With a decrease in arterial blood Oxygen tension in the kidneys produces erythropoietin, a hormone that stimulates erythropoiesis in the red bone marrow.

With insufficient formation of erythropoietin in patients with severe nephrological diseases, with removed kidneys or for a long time undergoing hemodialysis procedures, severe anemia often develops.

The kidneys complete the formation of the active form of vitamin D 3 - calcitriol, which is necessary for the absorption of calcium and phosphates from the intestines and their reabsorption from the primary urine, which ensures an adequate level of these substances in the blood and their deposition in the bones. Thus, through the synthesis and excretion of calcitriol, the kidneys regulate the supply of calcium and phosphates to the body and bone tissue.

Metabolic function of the kidneys is their active participation in the metabolism of nutrients and, above all, carbohydrates. The kidneys, along with the liver, are an organ capable of synthesizing glucose from other organic substances (gluconeogenesis) and releasing it into the blood for the needs of the whole organism. Under fasting conditions, up to 50% of glucose can enter the blood from the kidneys.

The kidneys are involved in the metabolism of proteins - the breakdown of proteins reabsorbed from secondary urine, the formation of amino acids (arginine, alanine, serine, etc.), enzymes (urokinase, renin) and hormones (erythropoietin, bradykinin) with their secretion into the blood. are formed in the kidneys important components cell membranes lipid and glycolipid nature - phospholipids, phosphatidylinositol, triacylglycerols, glucuronic acid and other substances entering the blood.

Features of blood supply and blood flow in the kidneys

The blood supply to the kidneys is unique compared to other organs.

• Large specific value of blood flow (by 0.4% of body weight, 25% of the IOC)
• High pressure in the glomerular capillaries (50-70 mm Hg. Art.)
• Constancy of blood flow, regardless of fluctuations in systemic blood pressure (Ostroumov-Beilis phenomenon)
• The principle of a double capillary network (2 systems of capillaries - glomerular and peritubular)
• Regional features in the organ: the ratio of the cortical substance: the outer layer of the medulla: the inner layer -> 1: 0.25: 0.06
• The arteriovenous difference in O 2 is small, but its consumption is quite large (55 µmol / min. g)

Rice. Ostroumov-Beilis phenomenon

Ostroumov-Beilis phenomenon- the mechanism of myogenic autoregulation, which ensures the constancy of renal blood flow, regardless of changes in systemic arterial pressure, due to which the value of renal blood flow is maintained at a constant level.

Selection. Urinary (urinary) system

In the process of vital activity in the human body, significant amounts of metabolic products are formed, which are no longer used by cells and must be removed from the body. In addition, the body must be freed from toxic and foreign substances, from excess water, salts, and drugs.

Organs that perform excretory functions are called excretory, or excretory. They include kidneys, lungs, skin, liver and gastrointestinal tract. The main purpose of the excretory organs is to maintain the constancy of the internal environment of the body. The excretory organs are functionally interconnected. Shift functional state one of these organs changes the activity of the other. For example, with excessive excretion of fluid through the skin at high temperatures, the volume of diuresis decreases. Violation of the excretion processes inevitably leads to the appearance of pathological changes in homeostasis up to the death of the organism.

Lungs and upper respiratory tract remove carbon dioxide and water from the body. In addition, most aromatic substances are excreted through the lungs, such as ether and chloroform vapors during anesthesia, fusel oils during alcohol intoxication. If the excretory function of the kidneys is disturbed, urea begins to be released through the mucous membrane of the upper respiratory tract, which decomposes, determining the corresponding smell of ammonia from the mouth.

Liver and gastrointestinal tract excrete with bile from the body a number of end products of hemoglobin metabolism and other porphyrins in the form of bile pigments, end products of cholesterol metabolism in the form of bile acids. Also excreted from the body in bile medications(antibiotics, lures, inulin, etc. The gastrointestinal tract releases decay products nutrients, water, substances that came with digestive juices and bile, salts of heavy metals, some drugs and toxic substances (morphine, quinine, salicylates, iodine), as well as dyes used to diagnose diseases of the stomach (methylene blue, or congorot).

Leather performs an excretory function due to the activity of sweat and, to a lesser extent, sebaceous glands. Sweat glands remove water, urea, uric acid, creatinine, lactic acid, sodium salts, organic substances, volatile fatty acid etc. Role sweat glands in the removal of protein metabolism products increases in kidney diseases, especially in renal failure. With the secret of the sebaceous glands, free fatty acids, metabolic products of sex hormones, are excreted from the body.

The main excretory system in humans is the urinary system, which accounts for the removal of more than 80% of the end products of metabolism.

Urinary (urinary) system includes a complex of anatomically and functionally interconnected urinary organs that provide the formation of urine and its removal from the body. These bodies are.

The kidney is a paired organ that produces urine.

The ureter is a paired organ that removes urine from the kidneys.

The bladder, which is the reservoir for urine.

The urethra, which is used to carry urine to the outside.

It should be noted that more than 80% of the end products of metabolism are excreted with urine.

Bud( lat.ren; Greek nephros)

Paired organ, bean-shaped, red-brown color, smooth surface.

Kidney Functions :

1. excretory or excretory function. The kidneys remove excess water, inorganic and organic substances, products of nitrogen metabolism and foreign substances from the body: urea, uric acid, creatinine, ammonia, drugs.

2. Regulation water balance and, accordingly, blood volume due to changes in the volume of water excreted with urine.

3. Regulation of the constancy of the osmotic pressure of the liquids of the internal environment by changing the amount of excreted osmotically active substances: salts, urea, glucose ( osmoregulation).

4. Acid-base regulation by removing hydrogen ions, non-volatile acids and bases.

5. Blood pressure regulation by the formation of renin, the release of sodium and water, changes in the volume of circulating blood.

6. Regulation of erythropoiesis by secreting erythropoietin, which affects the formation of red blood cells.

7. Protective function: removal from the internal environment of the body of foreign, often toxic substances.

Kidney weight 120-200 grams. Vertical size 10-12 cm, width 5-6 cm, thickness 4 cm.

The kidneys are located in the retroperitoneal space, on the back abdominal wall, on both sides of lumbar spine.

Right kidney at the level of 12 thoracic - 3 lumbar vertebrae.

Left kidney at the level of 11 thoracic - 2 lumbar vertebrae.

As a result, the right kidney lies 2-3 cm lower than the left.

Fixing apparatus of the kidney:

Outside the kidney is covered fibrous capsule.

Outside it is fatty capsule, and outside of it renal fascia, in which there are two sheet:

a) front prerenal fascial plate,

b) back - retrorenal plate

These plates are connected to each other above the kidney and along its lateral edge, downward from the kidney, the plates of the renal fascia do not connect and the tissue of the fatty capsule of the kidney passes into the retroperitoneal tissue.

membranes of the kidney and renal vessels form fixing apparatus of the kidney. In fixing the kidney, intra-abdominal pressure is also important, supported by contraction of the abdominal muscles.

The external structure of the kidney.

The form- bean.

surfaces- front and back.

Ends (poles)- top and bottom. At the top end is the adrenal gland.

The edges- lateral (convex) and medial (concave). In the region of the medial edge are kidney gate. Through the gates of the kidney pass:

1. renal artery,

2. renal vein,

3. lymphatic vessels,

5. ureter.

The gate continues into a recess in the substance of the kidney renal sinus(sine), which is busy:

1. renal cups(big and small)

2.renal pelvis,

3. vessels and nerves.

All of them are surrounded by fiber.

small cups- there are 7-10 of them, they are short, wide tubes. Their one end captures the protrusion of the renal substance - renal papilla(can capture not 1, but 2-3), and continue with the other end into a large cup.

large cups- there are 2-3 of them, merging, they form the renal pelvis, from which the ureter departs.

The wall of the cups and pelvis consists of a mucous membrane, smooth muscle and connective tissue layers.

Internal structure kidneys.

On the frontal section, dividing the kidney into anterior and posterior halves, the renal sinus with its contents and the surrounding thick layer of the renal substance are visible, in which the cortical (outer layer) and medulla (inner layer) substance is isolated.

Brain matter. Its thickness is 20-25 mm. It is located in the kidney as pyramids, the number of which is 12 on average (can be from 7 to 20). Renal pyramids have a base facing the surface of the kidney and a rounded top or renal papilla directed to the renal sinus. Sometimes the tops of several pyramids (2-4) are combined into one common papilla. Between the pyramids protrude layers of cortical substance called kidney pillars. Thus, the medulla does not form a continuous layer.

Cortical substance. Represents a narrow strip of red-brown color 4-7 mm thick. and forms the outer layer of the renal parenchyma. It has a granular appearance and is, as it were, streaked with dark and lighter stripes. The latter, in the form of the so-called brain rays depart from the base of the pyramids and make up radiant part cortical substance. More between the beams dark stripes named folded part.

The radiant and the folded parts adjacent to it form renal lobule; renal pyramid and adjacent 500-600 renal lobules form renal lobe, which is limited by the interlobar arteries and veins that lie in the renal columns. 2-3 renal lobes are kidney segment. In total, 5 renal segments are isolated in the kidney 5 - upper, upper anterior, lower anterior, lower and posterior.

Microscopic structure of the kidney.

The kidney stroma is made up of loose fibrous connective tissue rich in reticular cells and reticulin fibers. The renal parenchyma is represented by epithelial renal tubules, which, with the participation blood capillaries form structural and functional units of the kidney -

nephrons. There are about 1 million of them in each kidney. The nephron is a non-branching long tubule, the initial section of which, in the form of a double-walled bowl, surrounds the capillary glomerulus, and the final section flows into the collecting duct. The length of the nephron in expanded form is 35-50 mm, and the total length of all nephrons is about 100 km.

Each nephron has the following departments passing one into another: renal corpuscle, proximal department, nephron loop and distal department.

renal corpuscle represents glomerular capsule and being in it glomerulus blood capillaries. The capsule of the glomerulus resembles a bowl in shape, the walls of which consist of two sheets: outer and inner. The cells covering the inner layer of the capsule are called podocytes. Between the leaves is a slit-like space - the cavity of the capsule.

proximal and distal departments nephrons are shaped like convoluted tubules and are therefore called proximal and distal convoluted tubules.

Loop of nephron (loop of Henle)) consists of two parts: descending and ascending, between which a bend is formed. The descending part is a continuation of the proximal convoluted tubule, and the ascending part passes into the distal convoluted tubule.

The distal convoluted tubules of the nephrons empty into collecting ducts, which mainly go in the renal pyramids towards the renal papillae. Approaching them, the collecting ducts merge, forming papillary ducts, opening with holes on the renal papillae.

The leaves of the nephron capsule and its tubules consist of a single-layer epithelium.

Nephrons are divided into:

cortical nephrons (about 80% of the total number of nephrons),

juxtamedullary nephrons (approximately 20%)

Let's stop at the building cortical nephrons. Features of the structure and functions of the second type of nephrons will be discussed below.

Cortical nephrons.

Their name is due to the fact that most of them are located in the cortical substance. Their renal bodies, proximal and distal convoluted tubules are located in the folded parts of the cortical substance, and in the radiant parts are the initial and final parts of the nephron loops and the initial parts of the collecting ducts. Part of the loops is in the renal pyramids.

The structure of the nephron must be considered in connection with its blood supply.

Blood supply to the kidneys. Despite its relatively small size, the kidney is one of the most vascularized organs. In 1 minute, up to 20-25% of the volume passes through the kidneys cardiac output. Within 1 day, the entire volume of human blood passes through these organs up to 300 times. The renal artery, which departs from the abdominal aorta, enters the hilum of the kidney and divides into two branches, which, in turn, are divided into segmental arteries (5). The segmental arteries are divided into interlobar arteries, running in the renal columns. The interlobar arteries are divided into arcuate arteries running on the border of the cortex and medulla. Depart from them interlobular arteries, going into the cortical substance between the renal lobules. From the interlobular arteries depart afferent arterioles, which enter the capsules of the nephrons. Entering the capsules, the afferent arterioles are divided into 40-50 capillary loops, forming renal (malpighian) glomeruli. There is no gas exchange in them. The capillaries of the renal glomeruli merge to form efferent arterioles, d whose diameter is approximately 2 times less than that of the afferent arterioles. After leaving the capsules, the efferent arterioles are divided into capillaries, braiding the tubules of the nephrons. In these capillaries, gas exchange occurs and already venous blood flows out of them. The name of the intrarenal veins is similar to the name of the intrarenal arteries. Deoxygenated blood from the kidney through the renal vein flows into the inferior vena cava.

Thus, the blood supply to the kidneys has the following features.

The presence of two capillary networks: the capillaries of the vascular glomeruli and the capillaries braiding the tubules of the nephron.

In the capillaries of the vascular glomeruli, gas exchange does not occur, as a result, arterial blood flows through the efferent arterioles.

Since the diameter of the efferent arterioles is smaller than that of the afferent ones, a high hydrostatic pressure (70-90 mm Hg) is created in the capillaries of the vascular glomeruli.

Juxtamedullary (paracerebral) nephrons.

Their renal (Malpighian) bodies are located in inner layer cortex, on the border with the medulla.

Features of the structure of juxtamedullary nephrons compared with cortical nephrons:

the afferent arterioles are equal in diameter to the efferent arterioles

the loops of Henle are longer and descend almost to the top of the papillae,

the efferent arterioles do not break up into a peritubular capillary network, but descend into the medulla, where each of them breaks up into several straight parallel vessels. Having reached the top of the pyramid, they return back to the cortical substance and flow into the interlobular or arcuate veins.

Juxtamedullary nephrons are less active in urine production. Their vessels play the role of a shunt, i.e. shorter and easy way, through which blood is partially discharged, bypassing the cortical substance.

Juxtaglomerular apparatus (JGA)

Each nephron is equipped with a complex of specialized cells located at the entry and exit site of the afferent and efferent arterioles and forming the juxtaglomerular apparatus. JGA cells secrete a biologically active substance into the blood - renin, under the action of which the vasoconstrictor substance angiotensin is formed in the blood plasma. Renin also stimulates the formation of aldosterone in the adrenal cortex.

Ureter(Latin ureter)

It's double tubular organ 30-35 cm long, connecting the renal pelvis and the bladder. Function: constant and uniform excretion of urine from the renal pelvis into the bladder.

Location: about t of the renal pelvis descends along the posterior abdominal wall retroperitoneally, bends through the entrance to the small pelvis, while crossing the iliac vessels in front. Below the ureters descend along the walls of the small pelvis, heading towards the bottom Bladder.

Depending on the location in the ureter, three parts:

abdominal,

pelvic, which have approximately the same length, equal to 15-17 cm,

intraparietal, 1.5-2 cm long. , which is obliquely under acute angle passes through the wall of the bladder.

The ureter has three constrictions:

at the very beginning of the ureter (clearance 2-4 mm.),

at the point of transition to the small pelvis (clearance 4-6 mm.),

in the wall of the bladder (clearance 4 mm.).

Wall structure:

mucous membrane- covered with transitional epithelium and collected in longitudinal folds,

smooth muscle membrane- in the upper two thirds it consists of an inner longitudinal and outer circular layers; in the lower third, a third layer is added to them - the outer longitudinal. The muscular layer, due to its peristalsis, contributes to the flow of urine into the bladder.

adventitious sheath.

Bladder(Latin vesicaurinaria; Greek cystis)

This is an unpaired hollow organ, the shape of which changes depending on the degree of filling it with urine. Capacity in adults is approximately 250-500 ml.

Functions:

1. is a reservoir for the accumulation of urine,

2. excretion of urine, manifested in urination.

Location: located in the pelvic cavity. Ahead of the bladder is the pubic symphysis, separated from the bladder by tissue. Behind the bladder: a) in women - the uterus and part of the vagina, b) in men - the seminal vesicles and part of the rectum.

Parts of the bladder.

1. top - facing forward and upward. At strong filling bladder rises above the pubic symphysis by 4-5 cm and is adjacent to the anterior abdominal wall.

2. Body - the large, middle part of the bladder, running from the apex to the confluence of the ureters.

3. Bottom - located behind and below the mouths of the ureters. Under it, men have prostate, and in women the urogenital diaphragm.

4. Neck - the place where the bladder enters the urethra. There is an internal hole in the neck area urethra.

Wall structure.

The wall thickness of an empty bladder is 12-15 mm, and that of a filled bladder is 2-3 mm.

The inner shell is mucous membrane with a submucosal layer. It is covered with transitional epithelium and forms numerous folds that smooth out when filled. At the bottom of the bladder, posterior to the internal opening of the urethra is bladder triangle – triangular area, devoid of folds, because there is no submucosal layer. At the vertices of the triangle open:

a) two openings of the ureters,

b) the internal opening of the urethra.

2. Muscular sheath. It is made of smooth muscle tissue arranged in three layers:

a) outer and inner layers longitudinal,

b) middle layer circular. Around the internal opening of the urethra, it forms bladder sphincter (involuntary).

3. Outside, the bladder is partly covered by the peritoneum, partly by the adventitia. The empty bladder is covered by the peritoneum at the back. In the filled state, the bladder with its top protrudes above the pubic symphysis, lifting the peritoneum, which covers it from behind, from above and from the sides.

Urethra(lat.urethra)

The female urethra.

This is an unpaired hollow organ in the form of a tube bent backwards, 2.5-3.5 cm long, 8-12 mm in diameter.

It begins with the internal opening of the urethra in the region of the neck of the bladder, goes down and passes through the urogenital diaphragm. In this place, it is surrounded by bundles of striated muscle fibers, forming an arbitrary sphincter of the urethra. The female urethra opens with its external opening in the vestibule of the vagina 2 cm below the clitoris. The anterior wall of the urethra faces pubic symphysis, and back to the vagina.

In the wall of the female urethra, the mucous and muscular membranes are distinguished.

mucous membrane- well expressed, with longitudinal folds. The epithelium of the mucous membrane forms depressions of microscopic size - lacunae of the urethra where the branched glands of the urethra open.

Muscular sheath. It is formed by two layers of smooth muscle fibers: inner - longitudinal and outer - circular.

adventitious sheath.

male urethra

The male urethra has significant functional and morphological differences compared to the female.

His functions:

excretion of urine

ejection of semen at the time of ejaculation.

The male urethra is a narrow, long duct that runs from the internal urethral opening at the bottom of the bladder to the external urethral opening on the glans penis.

The total length of the urethra in an adult male ranges on average from 15 to 22 cm. The average width of the male urethra is 5-7 mm.

According to the position in the male urethra, there are 3 parts.

Presentation part. On average, it is 2.5 - 3 cm long. middle department this part of the urethra is wide, reaching a diameter of 9-12 mm. On the back wall this part of the urethra is an unpaired elevation -

seed mound, which opens two openings of the ejaculatory ducts. On the sides of the seed mound, numerous small holesprostate.

Webbed part. It is the narrowest (diameter 4-5 mm.), 1-1.5 cm long. It goes through the urogenital diaphragm from the prostate gland to the cavernous body of the penis. Surrounded urethral sphincter(striated, arbitrary), related to the muscles of the urogenital diaphragm.

Spongy part. This is the longest part of the urethra. It takes place in the spongy body of the penis.

It should be noted that after leaving the urogenital diaphragm, the urethra for 5-6 mm. passes outside the cavernous body and is located directly under the skin of the perineum. This is a weak point of the urethra, surrounded only by loose connective tissue and skin. The wall of the urethra here can be easily damaged by the careless introduction of a metal catheter or other instruments.

The spongy part of the urethra has two extensions:

a) in the bulb of the spongy body of the penis,

b) in the head of the penis (navicular fossa).

In the spongy part open two ducts of the bulbourethral glands.

The male urethra along its course has three contractions, which must be taken into account when performing manipulations in urological practice. These are the restrictions:

at the internal opening of the urethra,

in the membranous part,

at the external opening of the urethra.

The male urethra is S-shaped and two bends:

Anterior - it straightens when the penis is raised,

Rear - it remains fixed.

The structure of the wall of the male urethra. The mucous membrane of the male urethra contains a large amount of glands(Littre's glands), opening into the lumen of the canal. Their secret, together with the secret of the bulbourethral glands, neutralizes the remains of urine in the urethra and maintains an alkaline reaction that is favorable for spermatozoa when they pass through the urethra. In the spongy part of the urethra there are small, blindly ending indentations - gaps(crypts). Outside of the mucous membrane, the wall of the male urethra consists of a submucosal layer and a muscular membrane, represented by longitudinal and circular layers of smooth muscle cells.

The kidneys are paired parenchymal organs that produce urine.

The structure of the kidney

The kidneys are located on both sides of the spine in the retroperitoneal space, that is, the sheet of the peritoneum covers only their front side. The boundaries of the location of these organs vary widely, even within the normal range. Usually the left kidney is slightly higher than the right.

The outer layer of the organ is formed by a fibrous capsule. The fibrous capsule is covered with a fatty capsule. Renal membranes together with the renal bed and renal pedicle, consisting of blood vessels, nerves, ureter and pelvis, belong to the fixing apparatus of the kidney.

Anatomically, the structure of the kidney resembles the appearance of a bean. It has an upper and lower pole. The concave inner edge, into the recess of which the renal stalk enters, is called the gate.

On the section, the structure of the kidney is heterogeneous - the surface layer of dark red color is called the cortical substance, which is formed by the renal corpuscles, distal and proximal tubules of the nephron. The thickness of the cortical layer varies from 4 to 7 mm. deep layer light gray called medulla, it is not continuous, it is formed by triangular pyramids, consisting of collecting ducts, papillary ducts. The papillary ducts end at the apex of the renal pyramid with papillary foramen, which open into the renal calyces. The calyces merge and form a single cavity - the renal pelvis, which continues into the ureter at the hilum of the kidney.

At the microlevel of the structure of the kidney, its main structural unit, the nephron, is isolated. The total number of nephrons reaches 2 million. The composition of the nephron includes:

• Vascular glomerulus;
• glomerulus capsule;
• proximal tubule;
• Loop of Henle;
• distal tubule;
• Collecting tube.

The vascular glomerulus is formed by a network of capillaries in which filtration from the primary urine plasma begins. The membranes through which filtration is carried out have pores so narrow that protein molecules do not normally pass through them. When the primary urine moves through the system of tubules and tubules, ions important for the body, glucose and amino acids are actively absorbed from it, and the waste metabolic products remain and concentrate. Secondary urine enters the renal calyces.

Kidney Functions

The main function of the kidneys is excretory. They form urine, with which toxic decay products of proteins, fats, carbohydrates are removed from the body. Thus, homeostasis and acid-base balance are maintained in the body, including the content of vital potassium and sodium ions.

Where the distal tubule is in contact with the glomerular pole, the so-called "dense spot" is located, where the substances renin and erythropoietin are synthesized by special juxtaglomerular cells.

Renin formation is stimulated by a decrease blood pressure and sodium ions in the urine. Renin promotes the conversion of angiotensinogen to angiotensin, which can increase blood pressure by constricting blood vessels and increasing contractility myocardium.

Erythropoietin stimulates the formation of red blood cells - erythrocytes. The formation of this substance is stimulated by hypoxia - a decrease in the oxygen content in the blood.

kidney disease

The group of diseases that disrupt the excretory function of the kidneys is quite extensive. The cause of the disease may be an infection in different departments kidney disease, autoimmune inflammation, metabolic disorders. Often pathological process in the kidneys is a consequence of other diseases.

Glomerulonephritis is an inflammation of the glomeruli, which filter urine. The cause may be infectious and autoimmune processes in the kidneys. With this kidney disease, the integrity of the filtering membrane of the glomeruli is disrupted, and proteins and blood cells begin to penetrate into the urine.

The main symptoms of glomerulonephritis are edema, increased blood pressure and detection a large number erythrocytes, casts and protein in the urine. Treatment of kidneys with glomerulonephritis necessarily includes anti-inflammatory, antibacterial, antiplatelet and corticosteroid agents.

Pyelonephritis - inflammatory disease kidneys. The pyelocaliceal apparatus and interstitial (intermediate) tissue are involved in the process of inflammation. The most common cause of pyelonephritis is microbial infection.

Signs of pyelonephritis will be general reaction body for inflammation in the form of fever, feeling unwell, headaches, nausea. Such patients complain of lower back pain, which is aggravated by tapping in the kidney area, urine output may decrease. In urine tests, there are signs of inflammation - leukocytes, bacteria, mucus. If the disease recurs often, then there is a risk of its transition to a chronic form.

Treatment of kidneys with pyelonephritis in without fail includes antibiotics and uroseptics, sometimes several courses in a row, diuretics, detoxification and symptomatic agents.

Urolithiasis is characterized by the formation of kidney stones. The main reason for this is a metabolic disorder and a change acid-base properties urine. The danger of kidney stones is that they can block urinary tract and obstruct the flow of urine. With stagnant urine kidney tissue can easily become infected.

Symptoms of urolithiasis will be lower back pain (can be on one side only), aggravated after physical activity. Urination is frequent and causes pain. When a stone from the kidney enters the ureter, the pain spreads down into groin and sexual organs. Such episodes of pain are called renal colic. Sometimes after her attack, small stones and blood are found in the urine.

To finally get rid of kidney stones, you must adhere to special diet reducing stone formation. With small sizes of stones in the treatment of kidneys, special preparations are used to dissolve them based on urodeoxycholic acid. Some collections of herbs (immortelle, lingonberry, bearberry, dill, horsetail) have a therapeutic effect in urolithiasis.

When the stones are large enough or not amenable to dissolution, ultrasound is used to crush them. AT emergency cases may need surgical removal them from the kidneys.