Physiology of lactation

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1. Physiology of lactation PRESENTATION BY –SANDEEP KUMAR RN

2. Physiology of lactation preparation for effective lactation starts during pregnancy physiological basis of lactation is divided into four phases: mammogenesis 2. lactogenesis 3. galactokinesis 4. galactopoiesis Preparation of breasts Synthesis and secretion from the breast alveoli Ejection of milkh Maintenance of lactation

3. mammogenesis Pregnancy is associated with remarkable growth of both ductal and lobuloalveolar systems. An intact nerve supply is not essential for the growth of mammary glands during pregnancy.

4. The alveolar cells are the principal sites for production of milk. milk secretion actually starts on 3rd or 4th postpartum day. Around this time, the breasts become engorged, tense, tender and feel warm. Inspite of a high prolactin level during pregnancy, milk secretion is kept in abeyance. estrogen and progesterone circulating during pregnancy make the breast tissues unresponsive to prolactin. 2. lactogenesis

5. When the estrogen and progesterone are withdrawn following delivery, prolactin begins its milk secretory activity in previously fully developed mammary glands. Prolactin, insulin, growth hormone and glucocorticoids are the important hormones in this stage. Th e secretory activity is also enhanced directly or indirectly by growth hormone, thyroxine and insulin. Continuous

6. Oxytocin is the major galactokinetic hormone. Discharge of milk from the mammary glands depends not only on the suction exerted by the baby during suckling but also on the contractile mechanism which expresses the milk from the alveoli into the ducts. 4.Galactokinesis

7. durinG suCKlinG, a CondiTioned reflex is seTuP Th e ascending tackle impulses from the nipple and areola pass via thoracic sensory (4, 5 and 6) afferent neural arc to the paraventricular and supraoptic nuclei of the hypothalamus to synthesize and transport oxytocin to the posterior pituitary Oxytocin (efferent arc via blood) is liberated from the posterior pituitary, produces contraction of the myoepithelial cells of the alveoli and the ducts containing the milk milk ejection” or “milk let down” reflex whereby the milk is forced down into the ampulla of the lactiferous ducts, where from it can be expressed by the mother or sucked out by the baby. Presence of the infant or infant’s cry can induce let down without suckling. Presence ion of rise of pressure in the breasts by milk experienced by the mother at the beginning of sucking is called “draught”. This can also be produced by injection of oxytocin. Continuous

8. The ejection reflex may be deficient for several days following initiation of milk secretion and results in breast engorgement. milk ejection reflex is inhibited by - pain, anxiety, breast engorgement or adverse psychic condition (depression).

9. 4.GALACTOPOIESIS Prolactin -, Single most important galactopoietic hormone Maintenance of effective and continuous lactation – frequency of sucking (>8/24hr) essential Failur of sucking Distention of alveoli by retained milk Decrease secretion of milk by alveolar epithelium Lactation failure Healthy mother will produce about 500-800ml of milk a day to feed her infant

10. Stimulation of lactation Following delivery important steps – To put the baby to the breast at 2-3hr intervals from the 1 st day Plenty of fluids to drink Avoid breast engorgement 4.Exclusive Breastfeeding Start early (1/2-1hr) Lactation failur Infrequent sucking Endogenous suppression of prolactin Pain, anxiety, insecurity

11. Drugs to improve milk production Metoclopramide-increase prolactin level Sulpiride Domperidone Intranasal oxytocin Lactation suppression To stop breastfeeding To avoid pumping or milk expression To wear breast support Ice packs to prevent engorgement Analgesics to relieve pain A tight compression bandage is applied for 2-3day

12. Thanks Reference – DC DUTTA’S TEXTBOOK OF OBSTETRICS