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level: 16.7 The role of hormones in osmoregulation

Questions and Answers List

level questions: 16.7 The role of hormones in osmoregulation

QuestionAnswer
What may cause the lowering of water potential- Too little water being consumed - Much sweating occurring - Large amounts of ions, for example, sodium chloride, being taken in
Body response to fall in water potential (1)- Decrease in water potential of blood e.g. by sweating - This is detected by osmoreceptors in the hypothalamus - More ADH released by pituitary glands
Body response to fall in water potential (2)- Increases permeability of collecting duct to water by increasing no. of aquaporins - More h2o leaves collecting duct by osmosis - Increase in water potential of blood
Body response to fall in water potential (3)- When the water potential is returned to normal, osmoreceptors cause pituitary to release less ADH (=negative feedback)
Body response to rise in water potential (1)- The osmoreceptors in the hypothalamus detect the rise in water potential + increase frequency if nerve impulses to the pituitary gland to reduce its release of ADH
What may cause the rise of water potential (2)- Less ADH, via the blood, leads to a decrease in the permeability of the collecting ducts of water + urea - Less water is reabsorbed into the blood from the collecting duct
What may cause the rise of water potential (3)- More dilute urine is produced - Water potential of blood falls
What may cause the rise of water potential (4)- When the water potential of the blood has returned to normal, the osmoreceptors in the hypothalamus cause the pituitary to raise its ADH release back to normal levels (=negative feedback)