Lactation Flashcards
What are two functions of the breasts?
- Nutrition of the young
- Spacing of pregnancies
Where do the lactiferous ducts join the skin?
At the nipple
What causes the granular texture on the surface of the areola?
Sebaceous glands
What comprises the majority of breast tissue?
Adipose tissue from the pectoral fat pad
What is the function of Cooper’s ligaments?
Lift and support to the breasts
Breasts are modified ____ glands and are derived from _____ that arise between the axilla, armpit and groin
Sweat glands
Milk crests
Describe the embryological development of the breast.
- Development starts ~6wks gestational age
- Primary bud is a downgrowth of the dermis
- Secondary bud develops into primary buds and form the lactiferous ducts
- Breast bud lumen develops as gestation progresses
- Canalisation induced by placental steroids
What is witch’s milk and why does it form?
- Breasts are fully developed at birth and could produce milk
- Exposure to placental steroids and maternal hormones can cause production of witch’s milk
What effect does oestrogen and progesterone have on the breast during puberty?
- Promote growth of alveolar buds during menstrual cycle
- Successive cycles cause increased growth
What effect do the following hormones have on breast development and lactation?
- Oestrogen
- Progesterone
- Prolactin
- Growth hormone
- Insulin and cortisol
- Oestrogen: mitogen, essential for growth
- Progesterone: branching of ducts
- Prolactin: milk prod., alveolar development
- Growth hormone: same family as prolactin
- Insulin and cortisol: alveolar cell growth
What prevents milk production from occurring during pregnancy?
Inhibition by progesterone
- Prevents production
- Prevents milk ejection (smooth muscle relaxant)
What effect does baby suckling on the nipple have on hormone production?
- Prolactin
- Dopamine
- VIP
- Oxytocin
- Induces secretion of prolactin by anterior pituitary
- Decreases dopamine secretion
- Induces secretion of VIP (vasoactive intestinal peptide), acts on lactotrophs
- Synthesis and secretion of oxytocin from the posterior pituitary
What is the effect of oxytocin on the breast?
Induces contraction of myoepithelial cells of alveoli, causing injection of milk into ducts
What is the effect of prolactin on the breast?
Induces production of milk proteins
Through what mechanism does prolactin suppress FSH and LH?
Thought to be through effect on kisspeptin neurons in the hypothalamus
Where do supernumeroury nipples/breasts usually form?
On the embryonic milk ridge
What are the four stages of lactation?
- Lactogenesis stage I
- Lactogenesis stage II
- Galactopoesis
- Involution
What occurs in lactogenesis stage II?
- PP 3-8 days is the start of large scale milk production
- Increase in a-lactalbumin, decreased Na and Cl in milk
What causes dec. Na and Cl in milk in lactogenesis stage Ii?
Tight junctions in alveolar epithelium - reduce passage of salts
What is galactopoesis?
Lactation
Maintenance of established milk secretion
What is involution?
Lactation
- Cessation of breast milk production approx 40 days after last feed
How does the composition of colostrum compare to mature milk?
- Less fat and sugar
- More protein
- Rich in antibodies, mainly IgA
How dose lactose content in breast milk compare to cows’ milk? What is the significance of this?
- 6.8g vs 3.3g
- Lactose is an energy source and used for myelination
How does the casein:lactalbumin ratio compare in human and cows milk? What is the significance of this?
- 1:2 vs 3:1
- A-lactalbumin increases production of lactose (enzyme inducer)
