Lactation is a complex physiologic process under neuroendocrine control. It is the biologic completion of the reproductive cycle. Starting at about 16 week’s gestation the breasts develop and prepare for full lactation. In the first few postpartal hours and days the breast respond to hormones and the stimulation of the infants suck to produce and release milk.
PHYSIOLOGY OF LACTATION
The physiological basis of lactation is divided into four phases:
Mammogenesis or preparation of breasts
Lactogenesis or initiation of milk sectetion
Galactokinesis or ejection of milk and
Galectopoiesis or maintenance of established milk secretion.
Pregnancy is associated with a remarkable growth of both buctal and lobulo-alveolar system. During lactation the breast tissue is characterized by large numbers of alveoli. After lactation when, milk is no longer removed from the breast by the infant the alveoli gradually collapse and adipose tissue increases.
Complex nervous and endocrine factors are involved in the establishment of milk production in the first 2 to 5 days postpartum. Child birth results in a rapid decrease in oestrogen and progestron and an increase in prolactin secretion. Prolactin from the pituitary gland triggers milk production by stimulating the alveolar cells of the breast. Prolactin levels increase in responsible to tactile stimulation of the breast and sucking by the infant.
Discharge of milk from mammary glands depends not only on the suction exerted by the baby during sucking, but also on the contractile mechanism which expresses the milk from the alveoli into the ducts. The milk ejection is inhibited by factors such as pain, breast engorgement or adverse psychic condition.
Prolactin is the most important galactopoietics – hormone. For maintenance of effective and continuous lactation, suckling is essential as it causes release of porlactin. Milk pressure reduces the rate of production and hence periodic breast feeding is necessary to relieve the pressure which in term maintains the secretion.
Percentage Composition of colostrums and breast milk
PROTEIN FAT CARBOHYDRATES WATER
COLOSTRUM 8.6 2.3 3.2 86
BREAST MIKL 1.2 3.2 7.5 87