Physiology of Lactation

Hormonal Regulation of Lactation

Lactation is a complex physiological process primarily regulated by endocrine signals that ensure proper milk production and secretion.

Key Hormones Involved

• Prolactin: Essential for milk synthesis, stimulated by suckling and inhibited by dopamine.
• Oxytocin: Facilitates milk ejection by inducing myoepithelial cell contraction.
• Estrogen & Progesterone: Prepare mammary glands for lactation during pregnancy but inhibit milk secretion until postpartum.
• Cortisol & Insulin: Support metabolic activity for sustained lactation.

Mechanism of Milk Production

The lactation process begins during pregnancy with mammary gland development. Once the baby is born, prolactin stimulates alveolar cells in the mammary glands to produce milk.

Milk Ejection Reflex

Oxytocin triggers the contraction of myoepithelial cells, pushing milk from alveoli into ducts where it can be expressed through the nipple.

Regulation by Feedback Mechanisms

The continuous cycle of milk removal maintains lactation, as frequent suckling enhances prolactin release while inhibiting dopamine.