Breastfeeding Flashcards
What is the structure of the breast?
20 lobules radiating around areola
Duct system draining down to the nipple
Lobules further divide into structures that produce milk
Which has more fat? The lactating or non-lactating breast?
Non-lactating breast (has 50% fat) has more
Lactating breast has hyperplasia of glandular tissue that takes up the space
Describe the structures located near the nipple
9 ducts emerge at the nipple where milk is secreted – ducts are tortuous and branch near the nipple
70% of glandular tissue is located within 8cm of the nipple
What type of epithelial cells surround alveoli?
cuboidal or low columnar myoepithelial cells surround the alveoli
What do myoepithelial cells do?
They contract and are responsible for milk ejection
What is lactogenesis I?
Preparing the breast for milk production during pregnancy
Increase in human placental lactogen (HPL) + prolactin once pregnant
This causes hyperplasia of the glandular tissue within the breast
High progesterone + oestrogen from placenta inhibit milk production but breast is being prepared and increasing in size
What is lactogenesis II?
Fall in progesterone + oestrogen = no more inhibition
Milk production = lactogenesis post partum
Suckling of infant on breast = stimulation on prolactin = milk synthesis
Also release of oxytocin = milk ejection (positive feedback)
Duct cells = autocrine inhibition = inhibition if there is lots of milk around anyway
How is milk synthesis controlled?
Mechanical stimulation of suckling
Release of prolactin from anterior pituitary
Acts on cuboidal cells of milk-producing alveoli to increase milk synthesis
When do prolactin levels peak?
Suckling episode stimulates more prolactin for the next feed
Prolactin causes milk synthesis
What is the let down reflex?
Suckling stimulates the hypothalamus to causes the release of oxytocin from posterior pituitary gland
Oxytocin causes myoepithelial cells to contract and secrete milk down the milk duct and out the nipple
Controlled by higher centres so can be stimulated by other stimuli as well
How do we augment lactation?
Encouraging lactation to occur
Increases prolactin secretion
What drugs augment lactation?
Dopamine antagonists. Domperidone + Metoclopramide (Galactogogues)
When would we augment lactation?
When a preterm infant is taken away to an incubator
Mother lacks the normal stimuli that allow her to produce breast milk
How can we suppress lactation?
Decrease prolactin secretion
What drugs suppress lactation?
Dopamine agonists e.g. bromocriptine + cabergoline
What are the 5 secretory pathways that get components of milk into the lumen of the milk-producing alveoli?
Exocytosis MFG Osmosis Immunoglobulin secretion Paracellular Route
How is exocytosis involved in making milk?
Milk proteins, lactose, calcium, phosphate (major components of milk)
Packaged into secretory vesicles
Secreted by exocytosis