Question

Make your own schematic diagram, based on your understanding, for the Renin-Angiotensin Aldosterone System in its role for the regulation of urine concentration and volume. Describe the effects of each parts involved.

Answer 1

• 
• Renin is secreted by the juxtaglomerular cells .
• In the presence of renin , angiotensinogen is converted into angiotensin I .
• In the presence of angiotensin converting enzyme secreted by the lungs , angiotensin I is converted into angiotensin II.
• Angiotensin II increases blood pressure by directly acting on the blood vessels and causes vasoconstriction.
• Angiotensin II acts on the adrenal cortex and increases the secretion of aldosterone . Aldosterone acts on the distal convoluted tubule of the kidney and increases retension of sodium in kidney which again is responsible for the elevation of blood pressure.
• Angiotensin II acts on the kidney directly. It constricts the efferent arteriole which causes decrease in the glomerular filtration rate after initial increase of GFR.
• It contracts the glomerular mesangial cells which leads to decrease in the surface area of the glomerular capillaries and decreases the glomerular filtration rate.
• It increases the secretion of the antidiuretic hormone which is responsible for the conservation of water and maintains osmolarity of body fluids.