Explain regulation of ADH secretion and actions of ADH; include what osmoreceptors are.
- 1. High blood osmotic pressure stimulates hypothalamic osmoreceptors due to
(decline in blood volume)-diarrhea, -hemorrhage, -excessive sweating
Osmoreceptors-neurons in the hypothalamus that monitor blood osmotic pressure.
2. Osmoreceptors activate hypothalamic Neurosecretory cells that synthesize and release ADH
3. ADH into bloodstream from posterior pituitary, neurosecretory cells receive excitatory input from osmoreceptors. Excytosis cause ADH containing vesicles. Liberated ADH diffuses into capillaries of PP then carried to bloodstream to target tissues.
4.Kidneys stimulated; water loss; decrease output of urine, blood pressure increased
5. Low blood osmotic pressure inhibits the osmporeceptors
6. Reduce or stop ADH secretion. Kidneys retain less water forming a larger volume of urine, sweat glands increase and arterioles dilate. Blood volume and osmotic pressure of body fluids return to normal. (decreased urination can be caused by drugs, morphine, alchohol and nicotene)