The kidney's role in homeostasis

1. Renal metabolism

1.1. removal of waste products via urine formation

1.1.1. a. filtration: allows water and small solutes to pass but blocks blood cells and large proteins

1.1.2. b. reabsorption: of electrolytes and nutrients back into the bloodstream

1.1.3. c. secretion: of waste material (waste ions and hydrogen ions) into the renal tubules which when combine with filtrate becomes urine

2. Electrolytes Balance: The kidneys help maintain electrolyte concentrations by filtering electrolytes and water from blood, returning some to the blood, and excreting any excess into the urine.

2.1. 1. Sodium: help the body maintain the normal fluid levels in the fluid compartments

2.2. 2. Potassium: helps regulate fluid balance, muscle contractions and nerve signals

3. Regulation of Hormone

3.1. 1. Erythropoietin: regulates erythropoiesis or production of red blood cells in the bone marrow

3.1.1. when oxygen supply decrease in blood, red blood cells are produced

3.2. 2. Renin: an enzyme which catalyzes the conversion of angiotensinogen to Angiotensinogen 1 which is converted to Angiotensinogen 2 by ACE which stimulated the secretion of aldosterone and increase thirst

3.3. **aldosterone: causes vasoconstriction

4. Regulates the volume of body fluids

4.1. Increase BP: low BP will activate release of renin which cause the conversion of Angiotensin 1 to Angiotensin 2, stimulates release of aldosterone into the renal tubule to retain sodium and water and excrete potassium

4.2. ** Angiotensin Conventing Enzymes (ACE) Inhibitors: class of drugs that lower blood pressure by inhibiting the formation of angiotensin 2 and aldosterone