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Breast anatomy and milk making

posted Oct 14, 2009, 11:16 PM by Melissa Bugeja   [ updated Apr 10, 2015, 3:04 AM ]

Having an understanding of how your breasts work and make milk, will make you appreciate more the art of breastfeeding.

                                                How does the breast work?

 The lactation system inside the breast resembles a treeThe glandular tissues which make the milk are the leaves.   The ducts are the branches from which the milk travels. These ducts then flow into the larger tree trunk or milk sinuses which empty into the nipple through approximately twenty openings. The nipple appears as a short cylindrical protrusion through which the milk flows out of the breast and is surrounded by a patch of coloured and sometimes wrinkled skin called the areola. The milk sinuses are located beneath the areola. To empty the milk effectively, the baby’s gums must be positioned over them. When sucking only on the nipple, only a little milk is drawn out and the nipple gets irritated. In fact it is said that Babies feed on areolas not nipples (Sears).
  The baby’s sucking stimulates nerves in the nipples that send messages to the pituitary gland to the brain to secrete the hormone prolactin, which encourages continued milk production.  As the baby continues to suck, the sensors in the nipple signal the pituitary gland the release of another hormone, oxytocin.  This causes the tissue around each of the many milk glands to contract, squeezing a large supply of milk through the milk ducts into the sinuses and out of the nipple.  This is called the milk- ejection reflex (Sears).

 How is the milk made?

The making of milk begins mid pregnancy, when the body under the influence of the hormone prolactin starts the process to produce colostrum.  About three days postpartum, the milk starts coming in and at this stage women commonly feel fullness in their breasts which can lead to engorgement.  Around 9 days postpartum the last stage of milk making is reached and this ends whenever mother and baby decide to finish breastfeeding.  This is the stage of supply and demand.  It means that the amount of milk produced is dictated by how much milk is removed from the breast and therefore the more a breast is emptied, the more milk will be produced and that is how mothers with twins and triplets produce enough milk for all their children.

References: Martha Sears R.N & William Sears M.D The Breastfeeding Book
                    Carol L Wagner Human Milk and Lactation
                   Auerbach & Riordan Clinical Lactation: A Visual Guide