Regulatory Function of the Kidneys

Regulatory function of the kidneys: the role of the kidneys in regulating the composition of the blood and the volume of body fluids

The kidneys are a paired organ that plays an important role in regulating the composition of blood and other body fluids. Thanks to their ability to selectively excrete and reabsorb various substances, the kidneys help maintain the proper pH level of the blood, regulate the concentration of salts and the volume of body fluids.

One of the main functions of the kidneys is to regulate the pH of the blood. When metabolism results in excess acids or bases in the blood, the kidneys secrete them to maintain normal blood pH levels. This is especially important because changes in pH can have a negative impact on many biochemical processes in the body.

In addition, the kidneys regulate the concentration of salts in the blood and, therefore, the volume of body fluids. If the concentration of salts in body fluids is higher than inside the cells, this can lead to dryness and cell death. If the concentration of salts in liquids is lower than inside the cells, then the cells begin to swell and burst. The kidneys help maintain the proper level of osmotic pressure of the fluids that bathe the cells to avoid such consequences.

In addition, the kidneys play an important role in regulating overall blood volume. After bleeding, when the total amount of blood decreases, blood pressure decreases. This leads to a decrease in filtration pressure in the kidneys, and less fluid is filtered from the glomeruli into Bowman's capsules. As a result, the kidneys produce less urine to conserve body fluids. After large amounts of fluid are ingested, blood volume, blood pressure, and filtration pressure increase, and as a result, urine volume increases, returning blood volume to normal.

The amount of urine excreted by the kidneys depends not only on the amount of fluid consumed, but also on the amount of salts and other solids that must be removed from the blood. If the food a person eats is too salty, the kidneys have to excrete more salt to maintain the proper level of osmotic pressure in the blood. As a result, the volume of urine increases because more water is required to remove solids.

In addition, the kidneys regulate the rate of reabsorption of water in the renal tubules using antidiuretic hormone secreted by the posterior pituitary gland. When the body needs to conserve water, the posterior pituitary gland releases more antidiuretic hormone, causing the kidneys to produce less urine. If the body does not need to conserve water, the posterior lobe of the pituitary gland secretes less antidiuretic hormone, which leads to an increase in urine volume.

Thus, the kidneys play an important role in regulating the composition of the blood and the volume of body fluids. They maintain proper blood pH levels, regulate salt concentrations and volume of fluids, and are also involved in regulating the reabsorption of water in the renal tubules. If kidney function is impaired, an imbalance in the composition of the blood and the volume of fluids can occur, which can lead to various diseases and complications.