The urinary system consists of. The human urinary system is now accessible to understanding. Structure of the organs of the urinary system

The human urinary system is an organ where blood is filtered, waste is removed from the body, and some hormones and enzymes are produced. The structure, diagram, and features of the urinary system are studied at school during anatomy lessons, and in more detail at a medical school.

The urinary system includes such organs of the urinary system as:

ureters;
urethra.

The structure of the human urinary system is the organs that produce, accumulate and excrete urine. The kidneys and ureters are components of the upper urinary tract (UTT), and the bladder and urethra are components of the lower parts of the urinary system.

Each of these bodies has its own tasks. The kidneys filter the blood, removing harmful substances from it and producing urine. The urinary system, which includes the ureters, bladder, and urethra, forms the urinary tract, which acts as a sewage system. The urinary tract carries urine out of the kidneys, storing it and then removing it during urination.

The structure and functions of the urinary system are aimed at effectively filtering the blood and removing waste from it. In addition, the urinary system and skin, as well as the lungs and internal organs, maintain the homeostasis of water, ions, alkali and acid, blood pressure, calcium, and red blood cells. Maintaining homeostasis is important to the urinary system.

From an anatomical point of view, the development of the urinary system is inextricably linked with the reproductive system. That is why the human urinary system is often referred to as the genitourinary system.

Anatomy of the urinary system

The structure of the urinary tract begins with the kidneys. This is the name given to the paired bean-shaped organ located in the back of the abdominal cavity. The kidneys' job is to filter waste, excess ions and chemical elements during the production of urine.

The left kidney is slightly higher than the right because the liver is right side takes up more space. The kidneys are located behind the peritoneum and touch the back muscles. They are surrounded by a layer of adipose tissue that holds them in place and protects them from injury.

The ureters are two tubes 25-30 cm long through which urine flows from the kidneys into the bladder. They go along the right and left sides along the ridge. Under the influence of gravity and peristalsis of the smooth muscles of the walls of the ureters, urine moves towards the bladder. At the end, the ureters deviate from the vertical line and turn forward towards the bladder. At the point of entry into it, they are sealed with valves that prevent urine from flowing back into the kidneys.

The bladder is a hollow organ that serves as a temporary container for urine. It is located along the midline of the body at the lower end of the pelvic cavity. During urination, urine slowly flows into the bladder through the ureters. As the bladder fills, its walls stretch (they can hold from 600 to 800 mm of urine).

The urethra is the tube through which urine exits the bladder. This process is controlled by the internal and external sphincters of the urethra. At this stage, the woman's urinary system is different. The internal sphincter in men consists of smooth muscles, while in the woman's urinary system there are none. Therefore, it opens involuntarily when the bladder reaches a certain degree of distension.

A person feels the opening of the internal sphincter of the urethra as a desire to empty the bladder. The external urethral sphincter consists of skeletal muscles and has the same structure in both men and women and is controlled voluntarily. A person opens it with an effort of will, and at the same time the process of urination occurs. If desired, a person can voluntarily close this sphincter during this process. Then urination will stop.

How does filtering work?

One of the main tasks performed by the urinary system is blood filtration. Each kidney contains a million nephrons. This is the name given to the functional unit where blood is filtered and urine is produced. Arterioles in the kidneys deliver blood to structures consisting of capillaries that are surrounded by capsules. They are called renal glomeruli.

As blood flows through the glomeruli, most of the plasma passes through the capillaries into the capsule. After filtration, the liquid part of the blood from the capsule flows through a number of tubes that are located near the filter cells and surrounded by capillaries. These cells selectively absorb water and substances from the filtered liquid and return them back to the capillaries.

Simultaneously with this process, metabolic wastes present in the blood are released into the filtered part of the blood, which at the end of this process turns into urine, which contains only water, metabolic wastes and excess ions. At the same time, the blood that leaves the capillaries is absorbed back into the circulatory system along with nutrients, water, ions that are necessary for the functioning of the body.

Accumulation and release of metabolic waste

The krin produced by the kidneys passes through the ureters into the bladder, where it is collected until the body is ready to empty itself. When the volume of fluid filling the bladder reaches 150-400 mm, its walls begin to stretch, and receptors that respond to this stretch send signals to the brain and spinal cord.

From there comes a signal aimed at relaxing the internal sphincter of the urethra, as well as a feeling of the need to empty the bladder. The process of urination can be delayed by force of will until the bladder is inflated to its maximum size. In this case, as it stretches, the number of nerve signals will increase, which will lead to more discomfort and a strong desire to stool.

The process of urination is the release of urine from the bladder through the urethra. In this case, urine is removed outside the body.

Urination begins when the urethral sphincter muscles relax and urine exits through the opening. Simultaneously with the relaxation of the sphincters, the smooth muscles of the bladder walls begin to contract to force urine out.

Features of homeostasis

The physiology of the urinary system is that the kidneys maintain homeostasis through several mechanisms. At the same time, they control the release of various chemicals in the body.

The kidneys can control the release of potassium, sodium, calcium, magnesium, phosphate and chloride ions into the urine. If the level of these ions exceeds the normal concentration, the kidneys may increase their excretion from the body to maintain normal levels of electrolytes in the blood. Conversely, the kidneys can retain these ions if their levels in the blood are lower than normal. Moreover, during blood filtration, these ions are reabsorbed into the plasma.

The kidneys also ensure that the levels of hydrogen ions (H+) and bicarbonate ions (HCO3-) are in balance. Hydrogen ions (H+) are produced as a natural byproduct of dietary protein metabolism and accumulate in the blood over time. The kidneys send excess hydrogen ions into the urine for removal from the body. In addition, the kidneys reserve bicarbonate ions (HCO3-) in case they are needed to compensate for the positive hydrogen ions.

The growth and development of body cells requires isotonic fluids to maintain electrolyte balance. The kidneys maintain osmotic balance by controlling the amount of water that is filtered and removed from the body through urine. If a person uses a lot amount of water, the kidneys stop the process of reabsorption of water. In this case, excess water is excreted in the urine.

If body tissues are dehydrated, the kidneys try to return as much as possible to the blood during filtration. Because of this, the urine is very concentrated, with a lot of ions and metabolic waste. Changes in water excretion are controlled by antidiuretic hormone, which is produced in the hypothalamus and anterior pituitary gland to retain water in the body when there is a lack of water.

The kidneys also monitor the level of blood pressure, which is necessary to maintain homeostasis. When it rises, the kidneys lower it, reducing the amount of blood in the circulatory system. They can also reduce blood volume by reducing the reabsorption of water into the blood and producing watery, dilute urine. If blood pressure becomes too low, the kidneys produce the enzyme renin, which constricts the vessels of the circulatory system and produces concentrated urine. At the same time, more water remains in the blood.

Hormone production

The kidneys produce and interact with several hormones that control various systems body. One of them is calcitriol. This is the active form of vitamin D in the human body. It is produced by the kidneys from precursor molecules that appear in the skin after exposure to ultraviolet radiation from the sun.

Calcitriol works together with parathyroid hormone, increasing the amount of calcium ions in the blood. When their levels fall below a threshold level, the parathyroid glands begin to produce parathyroid hormone, which stimulates the kidneys to produce calcitriol. The effect of calcitriol is that the small intestine absorbs calcium from food and transfers it into the circulatory system. In addition, this hormone stimulates osteoclasts in bone tissue skeletal system to the breakdown of the bone matrix, which causes the release of calcium ions into the blood.

Another hormone produced by the kidneys is erythropoietin. The body needs it to stimulate the production of red blood cells, which are responsible for transporting oxygen to tissues. At the same time, the kidneys monitor the state of the blood flowing through their capillaries, including the ability of red blood cells to carry oxygen.

If hypoxia develops, that is, the oxygen content in the blood drops below normal, the epithelial layer of the capillaries begins to produce erythropoietin and releases it into the blood. Through the circulatory system, this hormone reaches the red bone marrow, where it stimulates the rate of red blood cell production. Thanks to this, the hypoxic state ends.

Another substance, renin, is not a hormone in the strict sense of the word. This is an enzyme that the kidneys produce to increase blood volume and pressure. This usually occurs as a reaction to blood pressure falling below a certain level, blood loss, or dehydration, such as increased skin sweating.

Importance of diagnosis

Thus, it is obvious that any malfunctions in the urinary system can lead to serious problems in the body. There are a variety of pathologies of the urinary tract. Some may be asymptomatic, while others may be accompanied by various symptoms, including abdominal pain when urinating and various discharges in the urine.

The most common causes of pathology are infections of the urinary system. The urinary system in children is especially vulnerable in this regard. The anatomy and physiology of the urinary system in children proves its susceptibility to disease, which is aggravated by insufficient development of the immune system. At the same time, even a healthy child’s kidneys work much worse than those of an adult.

To prevent the development of serious consequences, doctors recommend taking a general urine test every six months. This will allow timely detection of pathologies in the urinary system and treatment.

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.

Structure and functions of the urinary system

Excretion is the process of removing unnecessary and harmful metabolic products from the body. The kidneys, lungs, sweat glands and intestines are involved in the release of metabolic end products. CO2 and water vapor are released through the lungs. A small amount of water and urea and mineral salts dissolved in it are excreted through the sweat glands. Most of the metabolic products are excreted through the urinary system.

The main organ of excretion is the kidneys. They have a complex structure, which reflects the complexity of their functions. In addition to the kidneys, excretory organs include the ureter, bladder, and urethra. The kidneys are a paired organ with a bean-like shape and a weight of up to 100 g. The kidneys are located in the abdominal cavity, adjacent to its posterior wall at the level of the lumbar vertebrae. The outside of the kidney is covered with a very dense connective tissue capsule, which is surrounded by a fatty capsule. Kidney tissue consists of two layers: the outer - cortical and the inner - medulla. The medulla forms 15-20 pyramids. In the middle of the pyramids there are thin tubes ending in holes in the papillae, which protrude into a small cavity - the renal pelvis. The kidney has a complex microscopic structure and contains about 1 million structural and functional units - nephrons. The nephron consists of a capsule (in the form of a two-layer cup), which contains a tangle of capillaries, and a system of tubules. The walls of the tubules are formed by one layer epithelial cells. The capsule is located in the cortical layer; a convoluted tubule of the first order departs from it, which goes into the medulla and, straightening, forms a loop. The loop returns to the cortex and there forms a convoluted second-order tubule that flows into the collecting duct. The collecting ducts, merging, open into the cavity of the renal pelvis, from which the ureters depart.

Urine is formed from blood plasma. The process of urine formation begins in the capsules of the outer layer of the kidneys. When blood passes through the capillaries of the glomeruli, water and substances dissolved in it are displaced (filtered) from its plasma. Filtration occurs because the vessel that brings blood to the glomerulus is wider than the vessel and removes blood from it. A ball is created high blood pressure, two or more times higher than the blood pressure in other capillaries. The filtered liquid is called primary urine. Up to 150-180 liters of primary urine can be formed in the body per day. In terms of the concentration of dissolved substances, primary urine does not differ from blood plasma. In addition to dissimilation products, it contains amino acids, glucose, ions of inorganic substances, etc. In primary urine, unlike blood plasma, there are no proteins, since they are not filtered. Thus, primary urine is a filtrate of blood plasma, and the main filtering force is the blood pressure in the capillary glomerulus.

From the capsules, primary urine passes into the primary tubule, then into the secondary tubule, which is densely intertwined with a network of capillaries. In this part of the nephron, most of the water and some substances are absorbed into the blood: glucose, amino acids, proteins, vitamins, ions of inorganic substances. Primary urine that enters the collection tube is called secondary urine. It contains urea, uric acid, ammonia, etc. Up to 1.5 liters of secondary urine can be formed per day. If the kidneys function normally, then there is no protein or glucose in the secondary urine. From the tubules, secondary urine is collected in the renal pelvis, and then through the ureters it enters the bladder. Filling the bladder causes its wall to stretch. The nerve endings that are in the wall are irritated, the signals enter the central nervous system, and the person experiences an urge to excrete urine. It is carried out through the urethra and is under the control of the nervous system.

Kidney functions: excretory; regulation of the volume of blood, lymph and tissue fluid, ensuring the constancy of osmotic pressure and ionic composition of fluids in the internal environment of the body; regulation of blood pressure and hematopoiesis.

Impaired kidney function. Prevention of diseases of the excretory organs

Impairment or cessation of renal function is caused by infection in the renal parenchyma. Hypothermia of the body, kidneys, and colds contribute to this. Kidney diseases also develop due to poisoning with salts of heavy metals, drugs, acids, etc. Consumption of too spicy foods has a harmful effect on the kidneys. Alcohol affects the epithelial cells of the kidneys, disrupting or stopping the formation of urine. Stones often form in diseased kidneys.

To prevent kidney disease, you should follow certain hygiene requirements: eat right, treat teeth and sore throats in a timely manner, strengthen your body, be careful with various poisons, take medications only as prescribed by a doctor, maintain personal hygiene.

The ability to explain the processes that occur with the patient depends on understanding what the human urinary system looks like.

The structure of the urinary system is a group of organs for the formation and excretion of urine in humans.

The organs of the urinary system consist of two kidneys, a pair of ureters, a bladder and a urethra (urethra).

The work of the organs is to remove waste products and slag from the human body. After eating and drinking, the body takes what it needs for itself, the rest is garbage that must be eliminated.

The bulk of these products are excreted through urine. Entire books have been written about the functions of the urinary system; we will focus on the most basic ones.

How does the human urinary system work?

The organs of the human urinary system resemble a pipeline organized to remove fluid from the body (see pictures). The anatomy of the urinary system includes the two kidneys, the ureter, the bladder, and the urethra. This mechanism is extremely complex, but I will try to explain it in simple terms.

It all starts with you drinking water and eating foods that contain liquid. All this enters the stomach, and subsequently into the blood. Then the kidneys start working.

1. - the first organ that participates in the work of removing urine from the human body. The kidneys act as a filter, clearing the blood of toxins and leaving in it substances beneficial to the body.

Nature has provided two kidneys for each person. They are located on both sides of the spine at waist level in the posterior wall of the peritoneum.

The size of the kidney is 10-12 cm. It is held in place by a fairly large amount of fatty and connective tissue. Directly surrounding the kidney is a transparent fibrous membrane that protects the kidney from infection and damage.

Urine excreted by the kidney is a waste product, a product of filtration. Blood passing through the renal system gets rid of unnecessary ballast and is cleansed. Urine from the kidney moves to the bladder through the ureter.