Final answer:
Lactation refers to the synthesis and secretion of milk from the mammary glands in response to an infant sucking at the nipple. Hormones like prolactin and oxytocin play a role in the production and ejection of milk. The level of prolactin increases during pregnancy, but is inhibited by other hormones until the placenta is expelled. The correct option is b. false
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 mother, consuming the fat reserves stored during pregnancy.
The mother's mammary glands go through changes during the third trimester to prepare for lactation and breastfeeding. When the baby begins suckling at the breast, signals are sent to the hypothalamus causing the release of prolactin from the anterior pituitary. Prolactin causes the mammary glands to produce milk. Oxytocin is also released, promoting the release of the milk.
Near the fifth week of pregnancy, the level of circulating prolactin begins to increase, eventually rising to approximately 10-20 times the pre-pregnancy concentration. However, estrogen, progesterone, and other placental hormones inhibit prolactin-mediated milk synthesis during pregnancy. It is not until the placenta is expelled that this inhibition is lifted and milk production commences. The correct option is b. false