Explain the Physiology of Lactation?

Lactogenesis is the onset of copious milk secretion around parturition, triggered by a fall in plasma progesterone levels. Although some colostrum is secreted after delivery (2-3 days), full lactation begins later. The first 2-3 days after delivery is a period of rapid lactation initiation, followed by the longer period of maintenance of lactation. This complex neuroendocrine process is facilitated by interplay of various hormones. Oxytocin and prolactin instigate the lactation process. Prolactin is responsible for milk production and oxytocin is involved in milk ejection from the  breast.

A cyclic process of secretary activity, luminal distention and expulsion of milk into the duct system continues throughout lactation as directed by the suckling of the infant and the let-down reflex. Regular sucking stimulates the continuation of milk secretion. Milk removal from the breast is a product of coordinated interaction between sucklings of the infant and let-down reflex of the mother, as depicted in the Figure . As the infant commences suckling, afferent impulses generated in the receptors in  the areola travel to the brain where they stimulate the release of oxytocin from the posterior pituitary. Oxytocin travels through the blood stream to the breast where it combines with specific receptors on the myoepithelial cells, stimulating them to contract and force milk from the alveoli into the mammary ducts and sinuses.

We all know that human milk contains several nutrients and that it is tailor made to meet the requirements of the growing infant.