Urinary system

The urinary system of a person performs the function of removing slag, unnecessary, harmful compounds, while maintaining the necessary amount of mineral salts and water in the body. This task is realized through the formation of urine in the kidneys in a certain volume and with a certain concentration.

The structure of the urinary system.

Its structure includes organs that produce urine (kidneys), accumulating and removing urine from the body (bladder, urethra, ureters).

The kidneys located in the space behind the peritoneum on both sides of the spine are shaped like beans. The left kidney is slightly higher than the right kidney. The upper edges of this paired organ are close to the spine, the lower ones are distant.

The kidney defines the lower and upper pole, the inner and outer edges. In the center of the inner edge are the gates (groove). Through them, the organ enters the nerves and artery, the ureter, the lymphatic vessels, the vein exit. The totality of these elements forms a renal pedicel.

The fat capsule, its own membrane and connective tissue fascia surround each kidney. In the kidney material is two layers - cerebral and cortical. The first is represented by twelve to fifteen formations in the form of a cone. They are called pyramids. Cortical substance seeps between nearby pyramids. The cortical layer has a thickness of four to thirteen millimeters.

The urinary system has several regulatory mechanisms.

The amount of water in the body affects the concentration of urine. Excessive volume of water contributes to the suppression of the release in the pituitary gland of antidiuretic hormone (ADH), which controls the absorption of salts and water. When there is a lack of water, sensitive special formations (osmoreceptors) are excited. In this case, ADH is released into the blood, which promotes the reabsorption (re-absorption) of water.

The urinary system carries out together with urine the excretion of water, salt, uric acid, urea. Isolation of these components is made and through the lungs, skin, intestines, salivary glands, however, they can not replace the kidneys.

The formation of urine, including the stage of fluid filtration from the blood, secretion and reverse absorption, is carried out in nephrons (constituents of the kidney tissue). In each nephron are kidney (Malpighian) bodies, which provide the filtration process, and the urinary tubules. Taurus is a semi-spherical two-walled chalice. The gap between its walls covers the capillary glomerulus. From the slit there is also a canaliculus.

Intravascular pressure (70-90 mm Hg) promotes the infiltration of the liquid part of the blood into the nephron capsule. This process is called filtration, the leaked liquid, respectively, is called "filtrate" (primary urine).

The urinary system forms a filtrate consisting mainly of water. The concentration of low molecular substances in the primary urine is approximately the same as in plasma. When the filtrate moves along the tubules, its composition constantly changes, eventually it becomes the final urine. The average urine volume is about one and a half liters per day.

The urinary system also includes a bladder in its structure. This organ performs the function of accumulating urine. In the organ wall is a powerful muscle shell. With its reduction, the volume of the cavity of the bladder decreases. In the area of the ureteral holes, the internal opening of the urethra are the sphincters (compressors). They regulate the urine flow.

To the bottom of the bladder are the tubes (ureters).

Excretion of urine outwards is carried out through the urethra leaving the bladder.