All are action of oxytocin, except-
Ans. is 'd' i.e., Contraction of lower uterine segment Oxytocin* Oxytocin is a nonapeptide, synthesized predominantly in the paraventricular nucleus of the hypothalamus along with its binding protein neurophysin II. Oxytocin has following physiological actions: -1) Uterus:# It increases the force and frequency of uterine contraction during labor.# Estrogens sensitize the uterus to oxytocin, while progestins decrease the sensitivity.# The increased contractility is restricted to the fundus and body, lower segment is not contracted, may even be relaxed at term.2) Breast:# Oxytocin contracts myoepithelium of mammary alveoli and forces milk into bigger sinusuids - Milk ejection or milk letdown reflex.* Oxytocin secretion is inhibited by sympathetic discharge and circulating catecholamines, by pain and enkephalins, by emotional stress, especially fear, and by alcohol.* Oxytocin Acts on G-protein coupled IP3-DAG system receptors (same as VI receptors).
Increased contractility of uterus
Contraction of myoepithelial cells
Milk ejection
Contraction of lower uterine segment
Endocrinology and Reproduction