Breast & Mammary Gland

What are the breast, areola & ******?

Breast: highly modified area of skin, specialised sweat glands produce nutritious secretions under hormonal influences. Aerola: area of melanin pigmentation, sebaceous glands & pressure receptors. ******: pigmented raised skin, darken after pregnancy

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What is the anatomy of the breast?

Mammary/alveolar gland within 12-20 distinct lobules, each lobe has its own duct system & separate opening to the ****** via the lacteiferous duct. A septa exits between lobes, attached to skin by fibrocollagenous bands (Cooper's suspensory ligament)

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What do the ductal systems end in? What changes happen at pregnancy?

Each ductal system ends in a cluster of blind ending terminal ductules. These ductules will transform into alveoli at pregnancy and produce milk at lactation

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How are progesterone & oestrogen involved in pregnancy?

Progesterone: high placental secretion, maintains myometrium, prevents endometrial shedding, stimulates breast development, suppresses ovulation (-ve feedback), inhibits immuno-rejection of embryo. Oestrogen: proliferation of mammary tissue

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What breast changes happen in pregnancy?

Increase in vascularity & melanin pigmentation, hyperplastic proliferation of terminal ductile epithelium & vacuoles in luminal epithelial cells. 2/3rd trimester: increase lipid rich proteinaceous secretion (not true milk) and support tissue

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How is milk produced in the lactating breast?

Milk fat synthesized in sER of alveolar->membrane bound droplets (increase size towards lumen), pinched off & released. Milk protein passes through Golgi, vacuoles released by exocytosis. Both need prolactin receptor activation on surface of alveolar

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What happens during pregnancy to prepare for postnatal nutrition?

Oestrogen, progesterone & placental prolactin are involved in increasing the breast & alveoli size. Prolactin stimulates lactogenesis, but milk production inhibited in pregnancy.

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What happens after parturition to prepare for postnatal nutrition?

Drop in levels of oestrogen & progesterone allows dominance of pituitary prolactin. This starts lactogenesis. Breast now more sensitive to prolactin. Thus alveoli become enlarged & functional. Prolactin stimulates alveolar cells to produce milk

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What two reflexes are involved in synthesis of breast milk?

Suckling induced: sensory info -> prolactin release (anterior pituitary), ****** stimulation essential, strength/duration influence prolactin levels. Let down: oxytocin causes contraction of myoepithelial cells to induce expulsion of milk into ducts

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What is the composition of breast milk?

Colostrum: yellow/creamy fluid, contains more protein/fat-soluble vit/minerals/high levels immnoglobulins. Transitional milk: more calories/lactose/water-soluble vit/proteins/elevated fat. Mature milk: high % H2O/lactose/fat/AA/minerals/vit A,D etc

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What are the immunologic advantages of breast milk?

Acquired immunity, provides varying degrees of protection e.g. secretory IgA has antiviral/bacteria/genic-inhibiting properties. Immunoglobulins, lysozyme & lactoferrin leads to modulation of proinflammatory response in sterile gut

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What are some disadvantages of breastfeeding?

Drugs/alcohol taken by mother transmit through breast milk, jaundice from milk may interrupt breastfeeding, mum personal aversion or poor nutritional/physical/mental health may be contradiction to nursing, transmission of HIV etc

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Breast & Mammary Gland

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