Question

1. Choose an example of a hormone (e.g epinephrine) that uses either cAMP or Ca++ as a second messenger. What are the stimuli for the release of the hormone? What are the steps in the process of changing what a target cell is doing? Give a specific example of a process that is changed in the target cell after the cell receives the hormone signal.

Answer 1

VASOPRESSIN (ADH)

Decreased blood pressure activates the kidney to release renin. Renin then causes release of angiotensinogen from the liver which is converted to agiotensin l and angiotensin ll. Angiotensin acts on adrenal cortex and posterior pituitary to release aldosterone and ADH which causes water and sodium retention and vasoconstriction and increases blood pressure.
low blood volume stimulates ADH release from posterior pituitary. The ADH binds to V2 receptors present on the apical membrane and activates cAMP formation through second messenger system. cAMP causes release of aquaporins from the vesicles through exocytosis. Aquaporins insert in the apical membrane and causes absorption of water from the collecting duct. This results in increased water reabsorption and decreased urine output.