Final answer:
Lactation involves the preparation of the breast during pregnancy and the production of colostrum post-birth. Suckling triggers milk ejection through oxytocin release, and breast milk composition adapts over time and even within a single feeding to meet the changing nutritional needs of the infant.
Step-by-step explanation:
Summarize the Process of Lactation and Changes in Breast Milk Composition
Lactation is a complex process preparing a woman's body to provide nourishment to her newborn. During pregnancy, hormones like prolactin promote the development of the lactiferous ducts and alveoli lined with lactocytes, which will produce milk. Colostrum, the first milk produced after birth, is rich in immunoglobulins crucial for the newborn's immune defenses. As lactation progresses, oxytocin released during suckling stimulates myoepithelial cells, causing them to contract and push milk from the alveoli towards the nipple for the infant to consume.
The composition of breast milk evolves from colostrum to transitional milk, and finally to mature milk. This ensures that at every stage of the newborn's development, their nutritional needs are met. During a single feeding session, the milk's composition varies: the initial foremilk hydrates the infant while the later hindmilk is richer in fat and provides satiety.