Function of Kidney, Functional Anatomy of the Kidney

Lecture II: Function of Kidney, Functional Anatomy of the Kidney

Function of Kidney:
1. Excretion of metabolic waste products: the kidney eliminate waste product of metabolism that are not needed by the body. These products include urea (from the metabolism of amino acids), creatinine (from muscle creatine), uric acid (from nucleic acids), bilirubin (from hemoglobin breakdown) and metabolites of various hormone the kidneys eliminate most toxins and other substances such as drugs.
2. Regulation of water and electrolyte balance: The capacity of the kidneys to alter sodium excretion in response to change in sodium intake is 10 fold than normal. This also true for water and other electrolytes such as potassium, calcium and hydrogen.
3. Regulation arterial pressure: By excreting variable amount of sodium and water, and secretary vasoactive factors such as rennin, that lead to formation of vasoactive products such as Angiotensin II.
4. Regulation acid-base balance: By excreting acid and by regulating the body fluid buffer stores. Kidneys eliminate certain types of acid such as sulfuric acid and phosphoric acid by metabolism of proteins.
5. Regulation of erythrocytes production: The kidneys secrete erythropoietin which stimulates the production of red blood cells; one important stimulus for erythropoietin secretion is hypoxia. The people with severe kidney disease, severe anemia develops as result of decreased erythropoietin production.
6. Regulation of 1, 25-Dihyroxy vitamin D3 production: the kidneys produce the active form of D3 (1, 25-Dihydroxy vitamin D3) calcitriol, which is essential for normal calcium deposition in bone and calcium reabsorption by gastro-intestinal tract. It play role in calcium and phosphate regulation.
7. Glucose synthesis: The kidneys synthesis glucose from amino acid during prolonged fasting (gluconeogenesis).