A diagram showing the way in which prolactin is stimulated and inhibited. Prolactin is a hormone involved in lactation and is secreted by the anterior pituitary. Some diseases may cause abnormal production of prolactin.
TRH: Thyrotropin-releasing hormone.
Gross anatomy of the breast. There are three groups of lymph nodes that drain breast tissue; the axillary nodes (75%), parasternal nodes (20%), and posterior intercostal nodes (5%).
- The breast is an organ whose structure is clearly linked with it's function - lactation and breastfeeding.
- The breast usually extends from the 2nd to the 6th rib vertically, and from the lateral edge of the sternum to the mid-axillary line horizontally.
- The internal mammary artery supplies 60-70% of the blood to the breast, the remainder by the lateral thoracic artery. 6,7
- During 1st trimester of pregnancy there is fast growth of the ductule-lobular-alveolar system in the breasts.5
- Near full term, glandular luminal cells begin to actively synthesise milk fat and proteins.
- After birth, prolactin stimulates alveolar cells to produce and release milk (lactogenesis).
- Prolactin, secreted by the anterior pituitary, responds to nipple stimulation and infant suckling. (See diagram below for the way in which prolactin is inhibited and released.)
- Milk ejection reflex = let down reflex. Mechanical pressure from the infant suckling, signals to the hypothalamus to release oxytocin from the posterior pituitary. Oxytocin causes myoepithelial cells, surrounding each alveolus, to contract which forces milk into the ductal system and out the nipple.
- Oxytocin release can occur without mechanical pressure from things such as hearing a baby cry or even just thinking about the baby.
- Colostrum is the first milk produced and is rich in antibodies. Although the amount of colostrum produced in the first few days after birth is quite small, mothers should be reassured that it is sufficient to meet the nutritional needs of the neonate.