Nephrology

The Mechanism and Function of the Kidneys

1. The Mechanism of the Kidneys

2. The Function of the Kidneys

1) Excrete waste materials

(1) Excrete uremic toxins
(2) Excrete excess drugs / toxic substances no longer required by the body

2) Adjust fluids

The kidneys adjust the concentration and amount of urine to maintain body fluids at a set level. For example, when there is less fluid within the body, the urine becomes more concentrated, and less urine is produced. Conversely, when there is more fluid in the body, the urine is less concentrated, and more urine is produced. In other words, the amount of fluid entering and leaving the body is well-balanced.

3) Adjust electrolytes

Electrolytes include sodium (Na), potassium (K), chloride (Cl), calcium (Ca), phosphorous (P), and magnesium (Mg). The kidneys have the function of maintaining the concentration of these electrolytes at normal levels.

4) Secrete hormones that stimulate hematopoiesis

Red blood cells in the blood are made by the bone marrow. The kidneys secrete a hormone known as erythropoietin, which stimulates hematopoiesis, and promote the production of red blood cells by the bone marrow. When this is insufficient, it leads to anemia. This is why anemia occurs when the kidneys are damaged.

5) Activates vitamin D

Once vitamin D is consumed through food, it is activated in the skin, liver, and kidneys to become activated vitamin D. Activated vitamin D has the function of absorbing calcium from the intestines into the blood. When the kidneys are damaged, there is insufficient calcium, and the bones become brittle.

6) Adjusts blood pressure

The kidneys secrete hormones such as renin, which adjust blood pressure. When the kidneys are damaged, the blood pressure is not adjusted and has a tendency to rise.