Function of Kidney

FUNCTIONS OF KIDNEY

The basic anatomic and functional unit of the kidney is the nephron. Each kidney contains 1 million nephrons. As the body fluid flows through these finely structured units, the nephrons perform four significant functions to support life.

1.     Filtering : The nephrons filter most constituents to prevent them from entering the blood, except red cells and proteins.

2.     Resorbing : Needed substances are resorbed as the filtrate continues along the winding tubules.

3.     Secreting : Additional ions are secreted to maintain acid base balance.

4.     Excreting : Unneeded materials are excreted in a concentrated urine.

The primary function of the kidney is to maintain the constant composition and volume of the blood. This includes the regulation of

1.     The osmotic pressure

2.     The electrolyte and water balance and

3.     The acid-base balance. The production of urine permits the elimination of excess water and solutes such as sodium, chloride and byproducts of metabolism such as urea, and ingested substances that may be toxic

4.     Kidneys are the exclusive site for the production of 1,25 dihydroxy cholecalciferol the active form of vitamin D. Improper function can lead to bone disease

5.     Kidneys produce erythropoietin - which is essential for the formation of RBC

6.     Renin is released from the kidney in response to low blood pressure directly and stimulates the production of aldosterone.

7.     Parathyroid hormone, calcitonin, insulin and gastrin are degraded by the kidneys.