Anatomy and Physiology of Lactation Flashcards

Which hormone is primarily responsible for milk synthesis and secretion in the lactating breast?

Answer: Prolactin

Prolactin, secreted by the anterior pituitary, is the primary hormone driving milk synthesis (lactogenesis) in the alveolar cells.

Which hormone triggers the milk ejection reflex (let-down) by causing myoepithelial cells to contract?

Answer: Oxytocin

Oxytocin, released from the posterior pituitary, causes myoepithelial cells surrounding the alveoli to contract, ejecting milk into the ducts.

The functional milk-producing unit of the breast is called the:

Answer: Alveolus

The alveolus is the microscopic sac lined with secretory epithelial cells (lactocytes) where milk is synthesized and stored.

During pregnancy, high levels of which hormone inhibit full lactogenesis despite rising prolactin levels?

Answer: Progesterone

High progesterone levels during pregnancy block prolactin receptors on alveolar cells, preventing full milk production until progesterone falls after placental delivery.

Lactogenesis II, the onset of copious milk production, typically occurs how many hours after birth?

Answer: 30–73 hours

Lactogenesis II generally begins 30–73 hours postpartum, corresponding to the drop in progesterone after placental delivery and the surge in prolactin activity.

The cells that surround alveoli and contract in response to oxytocin are called:

Answer: Myoepithelial cells

Myoepithelial cells form a basket-like network around each alveolus and contract when stimulated by oxytocin to propel milk into the ductal system.

Which breast structure opens onto the nipple surface and transports milk from the lobules outward?

Answer: Lactiferous ducts

Lactiferous ducts channel milk from the lobular-alveolar units toward the nipple, where 15–20 duct openings release milk during feeding.