Antidiuretic hormone (ADH) or Vasopressin ::
It is a polypeptide hormone released from posterior pituitary Its main actions are :;
(1) Constriction of capillaries and blood vessels to raise blood pressure and
(2) Retention of Na+and thus redusing the urine volume
Due to rise in blood pressure it causes cardiac slowing and hyperpnoea with occasional apnoea by reflex mecm The intestinal musces are also stimulated by vasopressin
Decrease in plasma volume increases osmotic pressure of the blood This causes release of vasopressin Other stimuli for vasopressin release are pain stress and hypoxia Decrease in plasma volume or osmotic pressure of blood and stimulation of atrial receptors inhibits the release of vasopressin through hypothalamus
Oxytocin ::
It is a polypeptide hormone of posterior pituitary gland The main action of oxytocin is contraction of uterus In addition it also causes contraction of myoepithelial cells in the ducts of glands to expell the accumulated milk from the mammary glands It facilitates transport of sperms in non pregnant female genital tract Oxytocin also stimulates contraction of gall bladder intestine and urinary bladder
0 Comments