Osmoregulation

Question 1

How do the kidneys regulate the water levels in the body if there is too much water?

Answer 1

• The blood water levels are detected in the hypothalamus in the brain
• When the water levels are too high the hypothalamus tells the pituitary gland to release less ADH into the bloodstream
• The decreased ADH which is released means less water will be absorbed into the blood so urine will be dilute

Question 2

How do the kidneys regulate the water levels in the body if there is too little water?

Answer 2

• The blood water levels are detected in the hypothalamus in the brain
• When water levels are too low the hypothalamus tells the pituitary gland to release more ADH into the bloodstream
• The cells in the collecting duct of the nephrons of the kidney have receptors for ADH
• The increased release of ADH makes the collecting duct becomes more permeable to water
• Water is drawn out of the collecting duct and the Loop of Henle which reabsorbs the water by osmosis back into the blood so urine will be concentrated