Milk, the source of life

This is the 4239th article of Da Yi Xiao Hu

Do you really know the source of human life - breast milk? Today, let's briefly introduce breast milk. First, let's talk about the anatomy of the mammary gland: the mammary gland has 15 to 20 lobes, which are like reservoirs. Each lobe has its own duct - the milk duct, which is like a river. The water from the reservoir flows into the fields through the river to nourish the earth, while the milk secreted by the mammary gland lobes flows to the nipple through the milk duct to nourish life.

Breast milk in numbers

A study on the cost and benefits of breastfeeding in the United States showed that if the exclusive breastfeeding rate reached 90%, $13 billion could be saved each year and 911 infant deaths could be prevented. Breast milk contains a lot of substances, including protein, fat, lactose, oligosaccharides, hormones, vitamins, active factors, cells, minerals, etc. But did you know that 88% of breast milk is water. It is currently known that there are at least 13 growth factors, 68 cytokines, 415 proteins, more than 200 oligosaccharides, a large number of cells and medium-chain fatty acids in breast milk.

How is milk produced?

The secretion of milk is mainly affected by two hormones, namely prolactin and oxytocin. The lactation reflex plays an extremely important role in the secretion of these two hormones. The lactation reflex refers to some behaviors that can stimulate the mother to produce milk. It is a natural reflex after the nipple is stimulated. After the baby sucks the nipple, the nerves distributed in the nipple feel stimulated, and the stimulation signal reaches the brain through the afferent nerve fibers to promote the release of prolactin. Under the action of prolactin, the lactating cells begin to produce milk. Similarly, after the stimulation signal is transmitted to the brain, it will also promote the release of another hormone, that is, oxytocin. Under the action of oxytocin, the mammary myoepidermal cells contract, increasing the pressure in the alveoli, and the newly produced milk will be transported from the alveolar cavity to the nipple through the milk duct, and then ejected. In addition, the external negative pressure generated by the baby's sucking also plays an important role in the transportation and discharge of milk.

Here we would also like to remind everyone that the secretion of prolactin and oxytocin is closely related to the mother's nutrition, sleep, mood and health. It can be seen that ensuring the mother's rest, sleep and diet and avoiding mental stimulation are crucial for milk secretion. Now that we understand the principles of milk production and emptying, we can better assist milk discharge, further improve breastfeeding efficiency, and minimize the probability of milk blockage.

Author: Shanghai Fifth People's Hospital Affiliated to Fudan University

Li Zijin Resident Doctor