physiology of lactation and lactation hormones

physiology of lactation/ physiology of breastfeeding

physiology of lactation relates a lot with pregnancy. Lactation is the secretion of milk from specialized glands (mammary glands) to supply nourishment to offspring.

During pregnancy, the hormones oestrogen and progesterone activate the breasts. the breasts become larger and produce some fluid called colostrum. During the puerperium, they are expected to secrete milk which is different from the colostrum. The secretion or production of milk is known as lactation. "physiology of lactation"

The hormone which initiates lactation is called prolactin. it is a secretion of the anterior pituitary gland. Prolactin is antagonized by the hormone oestrogen. For this reason, prolactin does not function until the level of oestrogen in the blood is low. The reduction in the level of oestrogen occurs within the first two days of the puerperium. This explains why milk is secreted from about the third day of the puerperium. The effect of prolactin wears off after eight days. Further production of milk and maintenance of lactation are discussed as follows."physiology of lactation"

Preparation for Lactation

Within the fifth or sixth month of pregnancy, the breast is ready to produce milk. During the latter a part of pregnancy, the woman’s breasts enter into the lactogenesis I stage. This is when the breasts create colostrum, a thick, sometimes yellowish fluid.

During this stage/level, high levels of progesterone inhibit most milk production.

At birth, prolactin levels stay high, while the delivery of the placenta results in a sudden drop in progesterone, estrogen, and human placental lactogen levels. This abrupt withdrawal of progesterone within the presence of high prolactin levels stimulates the copious milk production of the lactogenesis II stage.

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When the breast is aroused, prolactin levels in the blood rise and peak in about 45 minutes, then return to the pre-breastfeeding state about three hours later. The release of prolactin stimulates the cells in the alveoli to create milk. "physiology of lactation"

Maintenance of Lactation

The breasts should be able to produce enough mil for full or partial feeding of the baby for nine months post-partnum. In order to achieve this the following factors are necessary:

  1. Maternal good health: A mother should be physically and mentally well and she should be free from anxiety
  2. Stimulation of the breasts by the sucking reflex of the baby. The baby should suckle at the breasts at regular intervals
  3. Adequate emptying of the breasts by the baby sucking on them or by manual expression of the breasts.

When the baby sucks on the breast it stimulates the posterior pituitary gland to release an oxytocic or pressor factor. The oxytocic or pressor factor causes the plain muscles of the breast to contract thereby propelling the milk from the alveolar along the lactiferous ducts into the ampullae. The rhythmic compression of the baby's sucking action of the ampullae will empty the breast. As the breasts are emptied the acini cells are stimulated to produce more milk. "physiology of lactation"

The draught or "let down reflex" is a term used to describe the effect of the oxytocic factor on the breast. It is demonstrated by the dripping of milk from one breast as the baby sucks on the other breast. Again if one removes the baby's mouth from the breast during feeding, a shower of milk will escape via the nipple. It should be noted that oxytocic released during breastfeeding also causes uterine contractions hence "after pain" is felt more during feeding times. It is also for the above reason that breastfeeding is said to aid involution of the uterus." physiology of lactation"

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