The urinary organ system is a general plan of the structure of the function. The structure of the organs of the human urinary system. Functions of the kidneys and ureters

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Structure and function of the urinary system

The urinary system includes the kidneys and urinary tract (ureters, bladder, urethra) (Fig. 7.1).

Rice. 7.1.

The kidneys are the main excretory organ; they excrete with urine most of the final metabolic products, the main component of which is nitrogen (urea, ammonia, creatinine, etc.). The process of formation and excretion of urine from the body is called diuresis, the same term in medicine is usually used to denote the amount of urine excreted by the body over a certain period of time.

Kidneys perform a variety of functions in the body. They are involved in removing metabolic end products (urea, uric acid and other compounds) that are harmful to the body from the blood plasma. The kidneys remove foreign substances that enter the body with food and in the form of medications, as well as sodium, potassium, phosphorus, and water ions, which plays an important role in regulating the ionic composition of blood plasma, the amount of water and maintaining acid-base balance, i.e. . ensuring homeostasis. The kidneys produce hormone-like substances: renin, which is involved in the regulation of blood pressure, and erythropoietin, which stimulates the formation of red blood cells.

The kidneys are a paired organ that is located in the lumbar region, on the posterior abdominal wall, at the level of the XII thoracic, I-II lumbar vertebrae. With age, the topography of the kidneys changes. In a newborn, the upper edge of the kidney is at the level of the upper edge of the XII thoracic vertebra. After 5-7 years, the position of the kidneys approaches that of adults. At the age of over 50, the kidneys are located lower than in younger people. At any age, the right kidney is lower than the left.

The kidney is bean-shaped and weighs about 150 g (Fig. 7.2). There are two surfaces in the kidney - anterior and posterior; two poles - upper and lower; two edges - convex and concave. On the concave side there is the renal hilum, through which the ureter, nerves, renal artery, renal vein and lymphatic vessels pass. The renal hilum leads into the small renal sinus, where nerves, blood vessels of the greater and lesser calyces, the renal pelvis, the beginning of the ureter and adipose tissue are located.

Rice. 7.2.

kidney element

In children, the kidney is round and has a bumpy surface due to its lobular structure. Its length in a newborn is 4 cm, weight - 12 g. After a year, the size of the kidney increases 1.5 times, and the weight reaches 37 g. By 3 years, these parameters are 8 cm and 56 g. In adolescents, the length of the kidney reaches 10 cm, and weight - 120 g.

On the outside, the kidney is covered with fibrous, fatty capsules and fascia. The fibrous capsule has many elastic fibers. It is easily separated from the kidney and becomes clearly visible by the age of 5, and by 10-14 years it is close to the fibrous capsule of an adult. The fat capsule is located outside the fibrous capsule. It is most noticeable in the area of the renal hilum and on its posterior surface. There is no fat on the anterior surface. The fat capsule begins to form only by the 3rd year of life, continuing to gradually thicken. By the age of 40-50 it reaches its maximum size, and in old age it thins out and disappears. The renal fascia is a thin connective tissue membrane located outside the fat capsule and has two layers.

Fixation of the kidney (holding it in a certain position) is carried out by blood vessels and membranes, especially the renal fascia and fat capsule. Intra-abdominal pressure, maintained by contraction of the abdominal muscles, is also essential. A number of unfavorable factors (sharp weight loss, increased elasticity of the renal fascia) can lead to kidney prolapse.

The kidney has a cavity in which the renal cups and the upper part of the pelvis, and the renal substance itself are located. In the renal substance there are cortical And cerebral layers. The cortex has a thickness of 4 mm, is located along the periphery of the kidney and extends in the form of columns into the medulla, which is located inside and consists of individual lobules called renal pyramids.

Kidney growth occurs most intensively in the first year of life. By age 12, brain growth stops. The cortex grows until the end of adolescence, especially rapidly at the ages of 5-9 and 16-19 years. The thickness of the cortex in an adult compared to that of a newborn increases by 4 times, and the thickness of the medulla increases only by 2 times.

The pyramids merge at their apices, forming a papilla surrounded by a small cup, which contains the beginning of the urinary tract. Small cups are funnel-shaped, merge with each other, forming 2-3 large kidney cups, forming renal pelvis, into which the urine produced in the kidney is poured. The pelvis is a funnel-shaped cavity that passes into the ureter at the hilum of the kidney. The wall of the cups and pelvis consists of inner (mucosal), middle (muscular) and outer (connective tissue) layers.

The main structural and functional element of the kidney, in which urine is formed, is nephron(see Fig. 7.2). In humans, there are more than 2 million nephrons in both kidneys. The initial section of each nephron is the renal corpuscle, consisting of a vascular glomerulus and the surrounding Bowman-Shumlyansky capsule. The capsule resembles in its shape a double-walled bowl, consisting of two leaves - inner and outer. There is a slit-like space between the leaves. The inner layer, to which the vascular glomerulus is adjacent, is built of flat epithelial cells. The external one passes into the urinary tubule of the nephron. The following sections are distinguished in the tubule: initial (main), or proximal, middle (loop of Henle, which descends from the cortex into the medulla), intercalary (distal) and collecting duct. The wall of the nephron urinary tubule is built of epithelium, which differs in shape in different parts of the tubule. The epithelium of the main section is similar to the epithelium of the small intestine and is equipped with a border with microvilli. The total length of the urinary tubules of both kidneys reaches 70-100 km. Capsules, glomeruli and convoluted tubules make up the renal cortex, and radially grouped urinary tubules form the structure of the pyramids of the renal medulla and open with excretory openings in the papillae.

The circulatory system of the kidney is adapted to participate in urine formation. A blood vessel called the afferent vessel approaches the Bowman-Shumlyansky capsule. It branches into capillaries, which form the vascular glomerulus of the renal corpuscle. From the choroid glomerulus, blood flows into a vessel called the efferent vessel. Arterial blood flows in the afferent vessels, vascular glomeruli and efferent vessels. The outgoing vessel is smaller in diameter than the bringing one. This creates conditions of increased pressure in the capillaries of the glomerulus, which is important for the process of urine formation. The efferent vessel splits for the second time into capillaries, which entwine the nephron tubules in a dense network. Arterial blood flowing through these capillaries turns into venous blood. Consequently, the kidney, unlike other organs, has not one, but two capillary systems. This creates favorable conditions for the release of water and metabolic products from the blood, which is associated with the function of urine formation.

Process urine formation consists of three phases: filtration, reabsorption and secretion. The first phase leads to the formation primary urine as a result of filtration of blood plasma in the vascular nephron glomeruli. Filtration is carried out due to the difference in pressure in the capillaries of the glomeruli (60-70 mm Hg) and in the nephron capsule (40 mm Hg). A person produces approximately 150-180 liters of primary urine per day. Primary urine has a composition close to blood plasma: it contains amino acids, glucose, uric acid, salts, as well as metabolic products: urea, uric acid and other substances; Only high molecular weight blood proteins do not pass through the primary renal filter. During the reabsorption phase in the nephron tubules, reverse absorption (reabsorption) of a number of substances necessary for the body from primary urine into the blood occurs: amino acids, glucose, vitamins, a significant part of water and salts. Thus, from 150-180 liters of primary urine, about 1.5 liters are formed secondary urine. Secondary urine does not contain substances necessary for the body, since in the reabsorption phase they are absorbed back into the bloodstream, at the same time, the amount of substances that must be removed from the body sharply increases: urea, uric acid and other metabolic products. Reabsorption is associated with significant energy costs, due to which the kidneys consume more than 10% of the oxygen entering the body. Excessive content of certain substances in the blood leads to the fact that some of them are not absorbed from primary urine into the blood - for example, after excessive consumption of sugar, part of the glucose remains in secondary urine and is removed from the body. On the contrary, if there is a lack of certain substances in the body, they cease to be excreted in the urine - thus the kidneys regulate the constancy of the internal environment of the body. During the third phase, harmful substances are released into the urine, which cannot pass through the “kidney filter”. These include drugs (antibiotics), dyes and a number of other substances.

Regulating the volume of urine excreted is carried out by the action of antidiuretic hormone (ADH), produced by the pituitary gland when it receives signals about the thickening of blood plasma. The action of ADH is based on a change in the permeability to water of the walls of the distal tubule and collecting duct of the nephron (Fig. 7.3).

Composition of urine. Urine is a light yellow liquid containing, in addition to water, about 5% of various substances (2% urea, 0.05% uric acid, 0.075% creatinine, etc.). The daily volume of urine contains about 30 g of urea and 25 g of inorganic substances, some biologically active substances are also present: hormones (thyroid

Rice. 73. Scheme of regulation of urine volume by antidiuretic hormone (ADH) glands, adrenal cortex), vitamins (vitamin C, thiamine) and enzymes (amylase, lipases). Glucose is not normally detected in urine. When its concentration in the blood exceeds 160-180 mg%, glucose is released in the urine - glucosuria. The color of urine (from light yellow to orange-brown) depends on the concentration of urine and the excretion of pigments. The pigments are formed from bilirubin in bile in the intestine, where bilirubin is converted into urobilinoid and urochrome. In pathological conditions, urine may contain protein, glucose, blood cells, acetone, bile acids and other substances. The reaction of urine depends on the food: when consuming a large amount of meat food, the reaction becomes acidic, and when vegetables predominate, it becomes alkaline.

Urinary tract. Urine, continuously produced in the kidneys, flows through the ureters into the bladder, from which it is discharged from the body through the urethra. The ureters, bladder, and urethra make up the urinary tract.

Ureter in an adult, it is a tube about 30 cm long. Starting from the gate of the kidney, it first lies on the posterior abdominal wall, then descends into the pelvic cavity, where it passes through the wall of the bladder and opens with an opening into its cavity. The wall of the ureter is represented by three layers: mucous, muscular and connective tissue. The mucous membrane is lined with stratified epithelium, the muscular layer consists of circular and longitudinal smooth muscles, it is capable of peristaltic movement that promotes the movement of urine. In a newborn, the ureter is tortuous, its length is 5-7 cm, by the age of 4 it increases to 15 cm. The muscular layer of the ureters in young children is poorly developed.

Bladder is a reservoir of urine (Fig. 7.4) and is located in the pelvic cavity behind the pubic fusion of the pelvic bones, with which it is separated by a layer of loose connective tissue. Behind the bladder in men is the rectum, in women - the uterus. When filled, the bladder takes on a pear-shaped shape; when very full, its apex is adjacent to the anterior abdominal wall. The bladder is divided into an apex, a body and a bottom. The wall of the bladder consists of a mucous membrane with a submucosal layer, muscle and connective tissue layers. The bladder is covered from above, behind and partially from the sides by the peritoneum.

The mucous membrane of the bladder forms folds that are absent only in the area of the bottom of the bladder, where there is a smooth triangular area - the vesical triangle. At its corners, both ureters open and the urethra emerges. When the bladder is filled, the folds of the mucous membrane straighten out. The sphincter of the bladder has the appearance of a semilunar area of a reddish color, and the orifices of the ureters form depressions on the sides of the triangle. Approximately 2-3 times a minute, the holes open and urine from the ureters is released into the bladder.

The muscular lining of the bladder consists of inner and outer longitudinal and middle circular layers. The most powerful is the circular layer, which forms the internal sphincter in the area of the internal opening of the urethra.

Rice. 7.4.

1,2 - muscle layers; 3 - mucous; 4 - internal openings of the ureters; 5 - fold; 6 - triangle; 7 - internal opening of the urethra; 8 - urethra; 9 - external opening of the urethra

In a newborn, the bladder has a spindle-shaped shape, by the age of 3 it becomes pear-shaped, by 8-12 years - ovoid, then in adolescents and adults - again pear-shaped. The volume of the bladder in a newborn is 50-80 ml, at 5 years old - 180 ml, by 12 years old - 250 ml, in an adult - on average 350-500 ml. In children, the muscular layer of the bladder wall is weakly expressed, the mucous membrane is quite well developed and has pronounced folds, the connective tissue membrane is easily extensible, as a result of which the children's bladder is highly extensible when filled. It is located higher than in adults; later, as they grow older, its bottom drops.

Emptying the bladder occurs reflexively. When 250-300 ml of urine accumulates in the bladder, a pressure of 12-15 mm of water column is created inside it. Nerve impulses from the receptors in the bladder walls are transmitted to the micturition center in the sacral spinal cord. From there, signals travel through the pelvic nerves to the walls of the bladder, simultaneously causing the walls to contract and the urethral sphincter to stretch. The higher centers of urination are located in the frontal lobe of the cerebral hemispheres, which creates the possibility of voluntary regulation of urination.

Humoral regulation of urine formation is carried out by the hormone vasopressin, which is produced in the hypothalamus and enters the blood through the pituitary gland. This hormone enhances the reabsorption of water from primary urine, accordingly reducing the volume of secondary urine and increasing the concentration of salts in it.

In men, the urethra also serves to remove seminal fluid from the testicles. In an adult it has a length

16-22 cm and consists of prostatic, membranous and spongy parts. The prostatic part is the widest, its length is about 3 cm. On the back wall there is an elevation - the seminal tubercle, on which two ejaculatory ducts open to remove seminal fluid from the gonads. In addition, the prostate ducts open into the prostate. The membranous part is narrow and short, its length is about 1 cm, it is tightly fused with the urogenital diaphragm. The spongy part has a length of 12-18 cm, ends with the external opening of the urethra on the head of the penis and is located in the spongy body of the penis. The urethra has internal (involuntary) and external (voluntary) sphincters. In a newborn boy, the urethra is relatively long (5-6 cm), its rapid growth is characteristic of puberty.

Female urethra straight and 3-3.5 cm long, it is wider than the male one and is easier to stretch. The canal is lined from the inside with a mucous membrane, which contains a large number of glands that secrete mucus. It begins at the bottom of the bladder with an internal opening, passes through the urogenital diaphragm in front of the vagina, opens into the vestibule of the vagina with an external opening and also has two sphincters. The urethra of a newborn girl is 2.3-3 cm long, in the lower part it is curved and open in front, its muscular layer and external sphincter are formed at the beginning of puberty.

The urinary system, which is virtually identical in men and women, is responsible for maintaining the water-salt balance of the body and for removing metabolic products. It also includes the adrenal glands, which partially synthesize certain groups of hormones (including the sex group of estrogens). How do the kidneys work? Blood is filtered through them, from which excess moisture is separated along with indigestible mineral compounds. They are responsible for removing about 80% of all harmful substances and sodium compounds. In addition, the kidneys partially help the body produce erythrocytes - red blood cells, which carry vital oxygen. Let's look in more detail at the structure of the urinary system and what each of its components is responsible for.

Functions of the kidneys and ureters

The structure and functions of the urinary system are partially similar to the ordinary bloodstream. But instead of a heart there are kidneys, and the fluid moves through the ureters to the bladder. From there it enters the urethra, then out when visiting the toilet. The human urinary system is surrounded by several muscle groups that act as a pump. But the kidneys, located in the area of the 12th group of ribs, are secured by fatty tissue. If this layer is too thin, then a disorder such as a “wandering bud” occurs - it may slightly change its location. However, in most cases this does not lead to disruption of the blood filtration function.

The urinary system is designed in such a way that the kidneys filter the same amount of blood during a full circle of blood circulation. However, if one of them is removed, the body adapts to new working conditions. True, along with this there is a risk of developing numerous diseases caused by a “reboot” of the urinary system. Doctors prescribe mandatory clinical monitoring and commissioning for such people twice a year.

The normal weight of a healthy person’s kidney is from 120 to 200 g. Its weight can temporarily decrease due to the slow process of blood filtration - then we feel thirsty. The adrenal glands, which are located slightly higher, are shaped like glands. They synthesize several groups of hormones, the main of which are adrenaline and aldosterone. It is with their help that when a feeling of fear arises, our “superpowers” manifest themselves.

The kidney consists of so-called nephrons. About 2 thousand liters of blood pass through them daily. In the process of blood circulation, nephrons “select” 170 liters of fluid, which contains metabolic products. In fact, only 1.5 liters of already “concentrated” saline solution is excreted, which is known to everyone as urine.

The ureters, which begin just below the kidneys, are thin muscle fibers. Using wave-like movements, they push the liquid lower in portions - into the bladder. The structure of the ureter is such that a muscular valve is located in the lower part of the canal. But it only works in one direction - i.e. allows fluid into the bladder, but prevents it from flowing back into the ureter and, accordingly, the kidneys.

Bladder and urethra

Just behind the ureters is the bladder. Its structure and functions are simple to the point of banality. The organ is a hollow muscular sac. When at rest, it resembles a small saucer. As urine accumulates, it becomes like an inverted pear. In its lower part there is a group of sphincters. Their main function is to prevent spontaneous urination (i.e., fluid entering the urethra).

The muscle tissue that makes up the bladder is quite unusual. With increasing pressure, it stretches. At the same time, the acidic environment that urine has does not corrode the walls of the “bag”.

It should be noted that the bladder is cut by nerve fibers. With their help, the human urinary system sends a signal to the brain that it is necessary to visit the toilet and get rid of excess fluid. At the same time, receiving a response impulse, the group of sphincters relaxes, which leads to urine entering the urethra, and then out.

As for the urethra, it is slightly longer in men than in women. This is due to differences in the structure of the genital organs. By the way, this is also the reason why representatives of the fair sex more often suffer from disturbances in the functioning of the urogenital tract (inflammation). On top, the urethra is covered with several layers of muscle tissue, which works in exactly the same way as the sphincters in the bladder - when the appropriate signal is received, the fibers are compressed, and the exit to the outside opens.

Anatomical data

Inside each kidney is a pelvis, a small chamber for temporary storage of urine. It cannot expand in volume, so our body needs to rid itself of accumulated fluid several times a day. The aorta and inferior vena cava are also attached to the kidneys. Through them, already purified blood is brought in and out.

The size of the kidneys in diameter is from 10 to 12 cm, thickness - up to 4 cm. Their color can vary from pale gray to brown, depending on the stage of blood purification. The kidneys are completely surrounded by a transparent fibrous membrane. Its functions are to protect the kidneys directly from mechanical and infectious effects. Scientists have recently found that with its help, partial heat removal occurs during a sharp injection of adrenaline into the blood (then body temperature can temporarily rise to 38-39 º). When kidneys “overheat,” they significantly reduce their productivity, since the volume of blood that passes through them increases. Nephrons simply do not have time to cleanse themselves.

The ureter and bladder consist of 3 separate layers:

The first layer is the mucous membrane, which protects against the attachment of sodium compounds and corrosion of the epithelium.
The second layer is muscle fiber. It is thanks to the compression of the fibers that the fluid moves into the bladder, and then into the urethra. Muscle fibers have receptors that receive “signals” from the kidneys: when to start moving and when to close the sphincter that blocks the entrance to the bladder.
The last layer is the adventitia. This is a wall that attaches organs to fatty tissue and prevents the same ureters from bending, blocking the drainage of urine. It should be noted that the channels are responsible for supporting normal urodynamics. Those. a stream is applied in which salt deposits are washed out of the bladder. Sometimes their dysfunction leads to the formation of sand and calculi (stones).

The structure of the urinary system also means that the kidneys can extract nutritional components from the blood to stimulate regeneration.

It is surprising that scientists discovered this function of nephrons not so long ago, as well as the process of ionoregulation of blood. This is directly done by the adrenal gland, which is responsible for hormonal secretion.

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Physiological differences between men and women

The urinary system ends with the urethra and the orbicularis muscles that envelop it. In women, the urethra is only 4 cm long, in men it is up to 20 cm. If in the former the urethra is surrounded by only one muscle ring, then in the latter it is surrounded by two, and each of them is quite wide. True, the second ring is more responsible for the reproductive function.

By the way, it should be noted that in newborn girls under 1 year of age, the urethra is completely open, but this does not lead to the occurrence of any inflammatory processes. At the same time, in children under 5-6 years of age, the kidney volume is almost twice as large as in adults. This is due to the fact that before this period they “ripen”. In this case, the nephrons regenerate several times. Scientists have not yet established why this happens. The structure of children's and adult kidneys is identical, except that the nephrons are larger (but the same number).

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Characteristic diseases

The most common disease of the urinary system for which doctors are consulted is sand and stones in the kidneys and bladder. It occurs when there is an imbalance of mineral components in the blood or the development of any infectious diseases in which part of the urinary system becomes inflamed, making it difficult to push fluid into the urethra. Over time, sodium accumulations form in these places. If the problem is not corrected for a long time, this leads to the appearance of stones (calculi). Because of them, when urinating, the patient may feel a sharp pain radiating to the abdomen, kidney area, and solar plexus.

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Causes of dysfunction

As you know, the structure and functions of the urinary system are closely related to the reproductive organs. In particular, the male reproductive organ is a muscle and protein tissue that envelops the urethra. In women, the exit of the emission canal is located in the vaginal area. Accordingly, through these places the infection can penetrate the organs of the urinary system, after which inflammatory processes occur. Some types of bacteria have a penetrating function, which can affect the functioning of the kidneys and ureters. Sometimes this leads to spontaneous opening of the urethra, although such a disorder may also be a consequence of dysfunction of the circular muscles.

In the presence of inflammatory processes, the urinary system sends erroneous impulses to the brain. This is caused by increased blood flow to the receptors, which simply misunderstand the signal sent to them. It is because of them that we may feel a frequent urge to go to the toilet, although at the same time we cannot normally empty the bladder of urine.

And such a disturbance in the functioning of the urinary system is normal in pregnant women. But here everything is explained by the pressure caused by the increase in the volume of the uterus. By the way, the amount of liquid that can be stored in the bladder does not change - still the same 0.7-1 liters. However, when the bladder is only half full, the receptors are excited due to external pressure. That’s why the fair sex has to go to the toilet so often during pregnancy.

The human body is a “full cycle factory”, continuously producing many substances, many of which are harmful and must be eliminated from the body. There are several ways to do this. All harmful substances are eliminated through breathing, sweat, feces and urine. Thus, the urinary system is one of the main ways to get rid of everything harmful and unnecessary to the body. Its structure and diseases will be discussed today.

The most important organ that plays a leading role in detoxification processes. It is paired, but you can exist with one, and in case of genetic disorders, the kidney can be doubled. They are a parenchymal organ. Located in the lumbar region. The structure of the organ is quite complex. The organ consists of:

Capsules and barks. Nephrons are immersed in it, in which primary urine is formed. Hidden in the nephron is a glomerulus of capillaries, which is needed to filter water, urea and layers.
Brain substance. Primary urine passes through its tubules. They also return glucose and remaining water to the capillaries. After this, secondary urine remains and enters the pyramids of the kidney.
Renal pelvis. Secondary urine enters it from the pyramids and is sent to the ureters.
Gate of the kidney. Here an artery enters the organ and a vein exits. They are also the entrance to the ureters.
Inside the organ there are: renal column, adipose tissue, papilla, renal sinus and calyces (small and large).

The normal weight of a kidney is about 200 g, thickness is about 4 cm, length is from 10 to 12 cm. If the right kidney is slightly lower than the left, this is normal.

The main functions of the urinary system are:

getting rid of unnecessary and waste metabolic products;
maintaining homeostasis (meaning water-salt balance);
hormonal function (carried out by the adrenal glands).

Several organs work on all this at once:

kidneys;
ureters;
bladder;
urethra.

There are also secondary, but no less important organs, such as the aorta and inferior vena cava, as well as the adrenal glands, which are glands that synthesize hormones, including adrenaline and norepinephrine.

Ureters

They are thin and long tubes extending from the pelvis and flowing into the bladder. The ureters connect the bladder and pelvis. The walls of the organ consist of mucous (stratified epithelium), muscular and adventitial (connective tissue) layers. They are located in the retroperitoneal space, have a length of 28 - 34 cm, but the left one is usually slightly longer, which is due to the location of the kidneys. The basis of the organ is smooth muscle, the outer layer is connective tissue, and the inside is epithelium. It has the ability to peristalsis, in the area of the mouth, in the middle of the organ and in the area of \u200b\u200bthe connection with the pelvis it has narrowings.

Bladder

Quite a large organ located in the pelvis. It is an organ of smooth muscle, which is lined inside with epithelium. The top is covered with peritoneum. Comprises:

necks;
side, back and front walls;

The orifices of the ureters are located on the posterior wall of the organ. It has the shape of a bag, reaching a volume of 200 - 400 ml when filled. Urine accumulates for about three hours, when the walls contract, it leaves the urethra.

Urethra

Also called urethra. In women and men, this organ has differences in structure:

It is a tubular and unpaired organ.
It consists of smooth muscle, which is lined with epithelial tissue on the inside. Its task is to release urine into the external environment. Like the ureters, it has three layers. In men it is also needed for ejaculation and is located in the penis. The female urethra is wider, stretches well, is slightly shorter and is easily affected by infection.

Diseases of the urinary system

Unfortunately, all organs of the urinary system are susceptible to disease. Here are the most common ailments of this organ system.

Bladder:

hyperactive;
neurogenic;
(including interstitial);
hernias;
diverticulum;
Marion's disease;
tumors and cancer;
sclerosis of the bladder neck;
bladder neck stenosis;
structural anomalies.

Ureters:

strictures;
stones in the ureters;
Ormond's disease;
vesicoureteral reflux;
ureterocele;
neuromuscular dysplasia;
empyema of the organ stump;
ureteral tuberculosis;
tumors.

Kidneys:

structural anomalies;
pyelonephritis, chronic and acute;
cyst;
nephroptosis (prolapse);
glomerulonephritis;
hydronephrosis;
apostematous nephritis;
paranephritis;
abscess;
pyonephrosis;
carbuncle;
nephropathy (diabetic, during pregnancy);
acute and chronic renal failure;
tumors;
tuberculosis;
long-term renal compression syndrome.

Urethra:

fistulas;
urethritis;
anomalies (congenital narrowing, duplication, epispadias, hypospadias);
stricture;
prolapse (including mucous membrane);
diverticulum;
papillomas (aka condylomas);
polyps;
angioma;
fibroma;
caruncle;
injuries;
malignant tumors.

To diagnose any ailments of the urinary system, examinations such as laboratory diagnostics (urine and blood tests), cystoscopy, X-ray methods, ultrasound, MRI, CT should be carried out. Symptoms can be very different, but with many ailments of the urinary system, problems with urination, pain and changes in the appearance of urine can be noted.

The urinary system is one of the largest organ systems in our body. Its main task is to free the body from toxins. Not only the kidneys work for this, but also the ureters, bladder and urethra.

You can also learn about the urinary system in this video.

Excretion is the process of removing the end products formed as a result of metabolism from the body. The organs involved in excretion include the intestines, lungs, and skin. However, more than 90% of compounds are excreted by the urinary system. Next, let's look at its structure in more detail.

Structure and functions of the urinary system

Several organs are involved in the process of excretion. These include the kidneys, ureters, urethra and bladder. In some organs, metabolic products are processed. Through others, the actual elimination is carried out. So, urine formation occurs in the kidneys, accumulation - in the bladder. Excretion is carried out through the urethra. The kidneys are a paired organ. The system also contains ureters. They are presented in the form of hollow tubes. With their help, the kidneys and the urinary system, presented in the form of the urethra and bladder, are connected. The latter is a hollow organ. It is located in the pelvis. The connection between the bladder and the surface of the body is through the urethra. Unlike other organs, this channel has differences depending on gender. This is the general structure of the human urinary system.

Filtration organs

On the sides of the spinal column, in the area between the 12th thoracic and 2nd lumbar vertebrae, are the kidneys. They are adjacent to the back of the abdominal cavity. The right kidney is located slightly lower than the left. The organs are bean-shaped. The kidneys have posterior and anterior surfaces, lower and upper ends, as well as medial and lateral edges. The gate is located on the concave area (medial), facing the spine. They include arteries and nerves, lymphatic vessels, veins, and ureter exit. The fixation of the kidneys is facilitated by the membrane covering them. Fibrous tissue is directly adjacent to the substance of the organ. Outside this shell is a living capsule. It is surrounded in front and behind by the fascia of the kidney. The organ is covered in front by the peritoneum. Intra-abdominal pressure and blood vessels enhance the fixation of the kidneys. They enter and exit the organ. The kidney contains a cortex. Its thickness is 5-7 mm. It is located on the periphery. The kidney also contains medulla. It consists of 7-12 pyramids. The medulla faces the cortical base, and the apex faces the renal sinus. The organ also has pillars. They are formed due to the cortical substance wedging into the medulla.

Structural units

They are nephrons. This is a system of renal tubules that takes part in the formation of urine. One nephron can have a length in the range of 18-50 mm, but their total length is about 100 km. The number of elements in each kidney is about a million. The nephron includes a capsule and a three-part tube. It, in turn, consists of the proximal part of the first order convoluted tubule, the loop and the distal part of the 2nd order convoluted tubule. The initial part of the nephron is located in the cortex. It has the appearance of a double-walled cup, tightly covering the capillaries of the renal glomerulus, forming the so-called corpuscle. The proximal part is considered the most active part of the nephron. In it, the processes of urine formation take place most intensively.

Circulation

Its characteristics are associated with the ability of the kidneys to form urine, as a result of which, in fact, the release of metabolic products occurs. More than 40 liters of blood pass through the organs of an adult in an hour, and about 1000 liters per day. The system begins with an artery that enters the gate and disintegrates into small channels. They pass to the cortex between the renal pyramids. At their base they form arcuate arteries. The branches from them, in turn, extend to the cortex, where the afferent vessel runs from them into the renal capsule. In the bowl of the capsule, the arteries branch into capillaries, forming the glomerulus. The channels are collected into the efferent arterial vessel. Its diameter is approximately half that of the bearer. Due to this, increased (70-90 mm Hg) pressure is created in the glomerulus. When it decreases to 40-50 mm Hg. Art. urine formation stops. Leaving the glomerulus, the efferent vessels break up into venous capillaries. They gradually unite into larger vessels and exit the renal hilum. For such a specific structure, the branching is called the “wonderful network.”

Anatomical and physiological features of the urinary system

The vessels of the glomerulus and capsule are in close contact with each other. Together with increased pressure, this interaction provides conditions for the formation of urine. It is formed from blood plasma. As it flows through the vessels of the glomerulus into the capsule, due to filtration, almost all components pass into the lumen, except for the formed elements and protein compounds. This is how primary urine is formed. During the day, about 100 liters are produced. As primary urine passes through the tubules into the blood, a number of salts, water, and sugar are reabsorbed from it, resulting in the formation of secondary urine. Its quantity is about 1-1.5 liters. It has a higher concentration; There is 40 times more ammonia in it, and 70 times more urea. The final urine flows through the collecting ducts, passing first in the cortex and then in the medulla, towards the openings located at the tops of the pyramids. First it gets into the small and then into the large cups. After this, it flows into the pelvis, and from there it enters the ureter. Small calyxes are present in the amount of 7-10 pieces. They surround the papillae of the renal pyramids. There are about 2-3 large cups. There is one pelvis in each kidney. All these elements are located in the sinus, which is surrounded by adipose tissue.

Connecting channels

The ureters consist of three parts: the vesical, pelvic and large. The first is located in the thickness of the bladder. The wall of the ureter is covered with connective tissue, muscle and mucous membrane. Due to peristaltic contraction of the smooth muscles of the canal wall, urine moves through it.

Storage organ

The bladder has two openings for the ureters and one for the urethra. Through the latter, periodic emptying occurs. The wall of the bladder has 3 shells: connective tissue, muscle and mucosa. The capacity of the organ is about 0.5 liters. As it fills, the wall stretches, and the folds of the mucous membrane begin to straighten out. When the opening of the urethra is open, contraction of smooth muscles promotes emptying.

Urethra

In men and women, the beginning of the urethra is located on the wall of the bladder, in the internal (third) opening. In males, from there it passes through the prostate and penis, then opening at the head with an external opening. In women, the urethra only comes into contact with the genitals, opening into the vestibule of the vagina. In the area where the urethra runs along the urogenital diaphragm, a sphincter is formed near it. It consists of striated muscle tissue. The sphincter voluntarily regulates emptying.

Effect of physical activity

When performing exercises, the kidneys with the pelvis and calyces, as well as the ureters, are subject to slight displacement. On the right, changes are more pronounced and occur somewhat more often than on the left. Presumably this is due to the liver located on top. When performing exercises, the shape of the pelvis and cups remains the same. In the ureters, both the shape and degree of curvature change. After completing the exercises, the urinary system quickly returns to its original state in the process of vigorous deep diaphragmatic (abdominal) breathing.

Formation of structure

There are certain age-related characteristics of the urinary system. For example, the filtering organs of a newborn are thick and short. They protrude into the peritoneal cavity stronger than in an adult. On the surface of the kidneys, grooves are visible that correspond to the boundaries between their lobes. The organs remain lobulated for up to 2-3 years. The size of the kidneys in newborns varies. So, the left one is slightly larger than the right one. The weight of the first is 13-15 g, and the second is 11-12 g. After 3-5 years, the size of the kidneys does not increase. Growth continues into second childhood and adolescence. Upon reaching 15 years, the weight of the organs reaches about 225-250 g. Further development of the urinary system occurs slowly until 30-40 years. The location of the kidneys in newborns is lower than in adults.

Possible operational disruptions

This or that pathology of the urinary system can manifest itself in different ways. The most common sign of disorders is incontinence. The urinary system may malfunction when an infection enters. Diseases of other organs, inflammatory or malignant processes can also act as provoking factors. Examination of the urinary system is of great diagnostic importance in this case. If the development of any disorders is suspected, laboratory tests are prescribed. In many cases, radiography, ultrasound, and CT are used. The most common diseases that may impair the functions of the genitourinary system include the following:

Cystitis.
Weakness of the bladder muscles.
Urethritis.
Chronic renal failure.
Pyelonephritis.
Prostate adenoma.
Urolithiasis.

When the first signs of disturbances appear, you should consult a doctor. Many other vital processes in the body depend on how well the genitourinary system works.

The human urinary system is represented by the kidneys, ureters, urethra and bladder.

Main functions of the system:

Release of metabolic products;
Maintaining water-salt balance in the body;
Hormonal function due to biologically active substances synthesized by the adrenal glands.

It should be noted that the functions of excretion and maintenance of homeostasis are vital.

Bud

The kidney is a bean-shaped parenchymal organ consisting of a cortex and medulla. .

From the inside, blood vessels (inferior vena cava and aorta) enter the kidney through the renal gate. In turn, the ureters emerge from the kidneys in the same place.

On the outside, the organ is covered with fatty and connective tissue capsules.

The structural and functional unit of the kidney is the nephron - a collection of glomeruli and excretory tubules.

In general, the kidney is an organ that plays a major role in the detoxification process of the body. The remaining organs of the urinary system perform only the functions of storing and excreting urine.

Ureter

The ureter is a hollow tube with a length of up to 32 cm and a lumen thickness of up to 12 mm. The size of the ureter is purely individual and depends not only on a person’s height and build, but also on genetic factors. So, with developmental anomalies, the length may differ sharply from the indicated one.

The wall of the ureter has several layers:

Internal (mucous) – lined with multilayered transitional epithelium;
Medium (muscular) - muscle fibers are oriented in different directions;
The outer (adventitial) consists of connective tissue.
The function of the ureter is to remove urine from the kidneys by contracting muscle fibers and maintaining normal urodynamics.

M bladder

This is a hollow organ in which urine accumulates until the moment of urination. The signal for the urge to urinate is the volume of accumulated urine of 200 ml. Bladder capacity varies, but the average is 300-400 ml.

The bladder has a body, a bottom, an apex and a neck. Its shape changes depending on the degree of filling.

The wall on the outside is covered with a serous membrane, followed by a muscular (smooth muscle tissue), inside the bladder is lined with a mucous membrane consisting of transitional epithelium. In addition, glandular epithelium and lymphatic follicles are present. The muscle tissue is not homogeneous and generally forms a detrusor, which has a narrowing closer to the bottom - the sphincter of the bladder.

Urethra

Immediately from the bladder, urine, under the influence of muscle contractions, enters the urethra. Further, through the urethra (sphincter), it is released into the environment.

The urethra, like the ureter, consists of three layers. The epithelium of the mucous membrane varies depending on the location. In the prostate area (in men), the mucous membrane of the urethra is covered with transitional epithelium, then with multilayer prismatic epithelium, and finally, in the head area with multilayered squamous epithelium. On the outside, the canal is covered with a muscular layer and connective tissue consisting of fibrous and collagen fibers.

It should be noted that in women it is shorter than in men, which is why women are more susceptible to inflammatory diseases of the urogenital tract.

I offer you a visual video “Structure of the human urinary system”

Diseases of the urinary system

Diseases of all components of the urinary system can be infectious or congenital genetic. During an infectious process, specific structures become inflamed. Inflammation of other organs, as a rule, is less dangerous, but leads to unpleasant sensations: stinging and pain.

Genetic diseases are associated with abnormalities in the structure of a particular organ, usually anatomical. As a result of such disorders, the production and excretion of urine is difficult or impossible.

Genetic diseases include: In this case, instead of two kidneys, the patient may have one, two, or none at all (as a rule, such patients die immediately after birth). The ureter may be absent or may not open into the bladder. The urethra is also subject to developmental abnormalities.

Women are more likely than men to be at risk of contracting infectious agents because their urethra is shorter. Thus, the infectious agent can rise to higher organs in less time and cause inflammation.

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