Educational Resources

How the breast functions

The milk-producing breast can be compared in structure to a bunch of grapes with the grapes (alveoli) being the cells that make, store and secrete the milk. Each alveolus connects to small ducts which flow into larger ducts which lead to the nipple. A small amount of milk collects in the sinuses which lay under the areola, the dark skin surrounding the nipple. The baby’s jaws compress the areola, the tongue moves in a wave-like motion front to back and a vacuum results which extracts the milk.

When the areola is stimulated, two hormones are released: prolactin which causes the milk to be made and oxytocin which causes the milk to be squeezed out of the alveoli and into the ducts. The more a baby nurses, which stimulates the breast, the more milk is produced which builds up the milk supply.

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