Question

Describe the hormonal regulation of the kidney.

Answer 1

The kidney produces three important hormones, renin,eryhthropoitein and calcitrol

The Renin-angiotensin-aldosterone (RAAS) is a signalling pathway responsible for regulating the body's blood pressure, blood volume, sodium and potassium levels. When ever blood pressure is low or blood volume is low or sodium levles are low and potassium levels are high, the kidneys release an enzyme renin, this enzyme converts angiotensinogen produced by the liver into angiotensin -1, an enzyme by name ACE found in the lungs than converts angiotensin-1 to angiotensin -2, which causes blood vessel to constrict resulting in increasing in blood pressure, angiotensin-2 further stimulates adrenal gland to release another hormone aldosterone which acts on renal tubules to retain water and sodium and excrete potassium, together aldosterone and angiotensin-2 act to maintain blood pressure, blood volume and sodium levles in the blood.

. Erythopoietin is a protein hormone essential to production of red blood cells (erythrocytes), which themselves deliver oxygen to all tissues in the body. This hormone is synthesized in the kidney and its secretion is regulated by the amount of oxygen delivered to that organ. in a condition known as hypoxia, where blood concentration of oxygen is low, interstitial cells within almost all zones of the kidney begin to produce the hormone.erytropoietin, which increases the RBC so that more oxygen is deliverd to the tissues, but when When blood oxygen concentration is normal ,synthesis of erythropoietin occurs in scattered cells located predominantly in the inner cortex, in this condition there is no increase in production of this hormone.

Kidneys play an important role in calcium homeostasis, when blood levels of calcium are low, PTH (parathyroid hormone) blocks reabsorption of phosphate in the proximal tubule while promoting calcium reabsorption in the asscending loop of henle, distal tubule and collecting duct. If blood calcium levels increases than PTH release is inhibited.