Explain the role of oxytocin and relaxin in parturition and lactation.

Explanation

Relaxin - It is a hormone secreted by the placents and also found in corpus luteum. It helps in relaxation of the pelvic ligaments at the time of parturition.
(i) Oxytocin - It is a hormone produced by posterior lobe of pituitary gland. As pregnancy progresses, increase in oxytocin concentration promotes, uterine contractions which facilitale downward movement of the foetus. The powerful concentration of the uterine muscles leads to the expulsion of the baby through birth canal resulting in child birth or parturition.
(ii) It causes the "Let- Down" reflex - the actual ejection of milk from the alveoli of the mammary glands. During lactation, oxytocin also stimulates the recently emptied uterus to contract, helping it to return to pre pregnancy size.