Breastfeeding Flashcards
What is the anatomy of the breast?
- ~20 radially arranged lobeswith duct system draining to nipple
- 9 lobes are functional - each is a separate functional unit
- Non-lactating breast is about 50% fat, lactating is 30%
- Ducts are tortuous and branch near nippe
What is the structure of mammary glands?
- Basic-secretory unit is alveoli set within connective tissue structure
- Lined by mammary epithelial cells
- Myoepithelial cells surround alveoli - contractile, responsible for milk ejection
What causes lactogenesis post partum?
- Fall in P and oestrogen levels -> reduced inhibition to milk production
- Suckling releases prolactin driving milk synthesis (led by infant demand)
- Suckling (and higher centres) release oxytocin driving milk ejection
- Some autocrine inhibition from duct cells
What is the let-down reflex?
- Suckling causes afferent impulses to travel to CNS (hypothalamus)
- This promotes oxytocin release from posterior pituitary
- This travels in the blood to mammary gland
- Acts directly on myoepithelial cells to cause milk ejection
What is oxytocin?
- normally produced by paraventricular nucleus of hypothalamus and released by posterior pituitary
- Released in response to breastfeeding, stretching of cervix and uterus
- Helps with birth, bonding of the baby and milk production
What drugs suppress lactation?
- Dopamine agonists - bromocriptine, cabergoline
- Decrease prolactin secretion
What drugs augment lactation?
- Dopamine ANTagonists - domperidone, metoclopramide
- Increases prolactin secretion
What are the 5 main components of breast milk?
- Nutrients
- Ig (secretory IgA)
- Cells (macrophages and lymphocytes)
- Non-specific immune components
- GFs
What are the 5 secretory pathways involved?
- Exocytosis - major milk components such as proteins, lactose, ca and phosphate are packaged into vesicles and secreted by exocytosis
- Milk fat globule - TGs are synthesised in cytoplasm and sER, coalsece into droplets
- Osmosis - water moves from the cell in response to gradient set up by lactose; Na and K follow water
- Ig secretion - combine with receptor, transported in endocytotic vesicle and emptied into golgi or apical membrane
- Paracellular pathways - normally closed but can be open in pregnancy
What is the visible difference in breast-fed vs formula-fed babies?
- Breast = longer and leaner
- Formula = shorter and fatter
How does the volume and composition of milk change with time post-partum?
- As number of days increases post-partum, the volume of milk increases, as does the concentration of lactose
- The concentraions of Cl, Na and K all decline
How does the composition change during the feed?
- Fat concentration increases during feed
What nutritional benefits are there to the baby from breastfeeding?
- Human milk has more whey protein than casein, whereas cows milk is the opposite. Whey protein is more easily digested and promotes gastric emptying
- Lactoferrin, lysosyme and sIgA are whey proteins important in host defence
- Human milk contains more lipids important for brain and retinal development
What gastrointestinal benefits are there for the baby?
- Human milk improves gastric emptying - far more digestible
- Human milk is important in preventing necrotising enterocolitis in preterm infant
What immunity benefits are there?
- sIgA
- complement - high amounts of C3, able to opsonise bacteria with IgA
- Lactoferrin - inhibits bacterial growth by binding iron
- Lysosymes - cleaves peptidoglycans of bacterial walls
- Cytokines - anti-inflammatory predominate
- PAF acetylhydrolase - inhibits platelet activating factor
- Oligosaccharides - inhibit binding of enteric/ resp pathogens
- EGF - enhance development of GI epithelium
- Cells - neutrophils and macrophages
