Final answer:
Lactation is the process by which milk is synthesized and secreted from the mammary glands of the postpartum female breast. Breast milk provides nutrition and immunity to the infant and has a changing composition. Suckling triggers the release of oxytocin and stimulates the release of milk from alveoli.
Step-by-step explanation:
Lactation is the process by which milk is synthesized and secreted from the mammary glands of the postpartum female breast in response to an infant sucking at the nipple.
Breast milk provides ideal nutrition and passive immunity for the infant, encourages mild uterine contractions to return the uterus to its pre-pregnancy size (i.e., involution), and induces a substantial metabolic increase in the postpartum person, consuming the fat reserves stored during pregnancy.
Suckling triggers oxytocin release, which stimulates myoepithelial cells to squeeze milk from alveoli. Breast milk then drains toward the nipple pores to be consumed by the infant.
Colostrum, the milk produced in the first postpartum days, provides immunoglobulins that increase the newborn's immune defenses.
Colostrum, transitional milk, and mature breast milk are ideally suited to each stage of the newborn's development, and breastfeeding helps the newborn's digestive system expel meconium and clear bilirubin.
Mature milk changes from the beginning to the end of a feeding.
Foremilk quenches the infant's thirst, whereas hindmilk satisfies the infant's appetite.