What happens to ADH when you are dehydrated?
Reveal answer
Brain detects → pituitary releases more ADH → collecting duct more permeable → more water reabsorbed.
Key words: pituitary · permeable
3(i) EXCRETION · RECALL
3.28B ADH and the water content of the blood
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Which gland releases ADH?
Reveal answer
The pituitary gland.
Key words: pituitary
Why does alcohol cause more urine?
Reveal answer
Less ADH → collecting duct less permeable → less water reabsorbed.
Key words: ADH
What is meant by the term ADH?
Reveal answer
Antidiuretic hormone that increases collecting-duct water permeability.
Key words: ADH
What is meant by the term osmoreceptor?
Reveal answer
Receptor sensitive to water potential or solute concentration of body fluids.
Key words: osmoreceptor
What is meant by the term target cell?
Reveal answer
Cell with receptors for a particular hormone.
Key words: target cell
ADH response to water status, Low water potential/dehydration. ADH and collecting duct? Urine?
Reveal answer
ADH and collecting duct: More ADH; more aquaporins. Urine: Small volume, concentrated.
Key words: Low water potential/dehydration
ADH response to water status, High water potential/excess water. ADH and collecting duct? Urine?
Reveal answer
ADH and collecting duct: Less ADH; fewer aquaporins. Urine: Large volume, dilute.
Key words: High water potential/excess water
ADH response to water status, Return toward normal. ADH and collecting duct? Urine?
Reveal answer
ADH and collecting duct: Signal reduces by negative feedback. Urine: Output stabilises.
Key words: Return toward normal
True or false, and why? “The pituitary detects blood concentration alone.”
Reveal answer
False. Osmoreceptors are in the hypothalamus; ADH is released from the posterior pituitary.
True or false, and why? “More ADH makes more urine.”
Reveal answer
False. It increases water recovery, producing less urine.
True or false, and why? “ADH actively pumps water.”
Reveal answer
False. It increases aquaporin permeability; water moves by osmosis.
What does ADH stand for?
Reveal answer
Antidiuretic hormone.
Key words: antidiuretic
What happens to ADH release after drinking a lot of water?
Reveal answer
Blood water content rises → less ADH released → collecting duct less permeable → more dilute urine.
Key words: less ADH
Which organ is the target of ADH?
Reveal answer
The kidney (its collecting ducts).
Key words: kidney