Lecture 10 - The breast Flashcards
what are the breasts aka?
mammary glands
where and what from are the breasts formed?
start forming in the embryo from modified sweat glands
the mammary glands are derived from tissue that is first identified in the _______ _____ that arise between the ________ (______) and the ______
mammary crests, axilla (armpit), groin
abnormal breast development happens where?
along the lines of the mammary crests
when does breast development start?
begins with the formation of the mammary buds at about 6 weeks
describe the first development of the breast
it takes place as a down growth of the epidermis to form the primary breast bud
how do the secondary breast buds form?
form by branching off the primary breast bud
as gestation progresses, the buds develop what?
lumens, e.g the buds become canalised
what induces canalisation of the secondary breast buds?
placental steroids (oestrogen and progesterone)
how many lactiferous ducts are present at the time of birth?
around 15-20 per breast
true or false, by birth the breasts are fully developed and could potentially make milk
true, but there is no hormonal stimulus
what is witch’s milk?
the colostrum-like milk produced by a newborn due to the fetus being exposed to placental steroids and maternal hormones at birth
true or false, the internal breast structure is the same in males and females
true
what are the three external structures of the breast
body of the breast
nipple
areola
describe the nipple
a raised, usually cylindircal pigmented structure
where the lacterferous ducts join the skin at the nipple
describe the areola
pigmented circle of tissue surrounding the nipple
contains sebaceous glands which give a granular texture to the areola
what are the internal structures of the breast?
adipose tissue of the pectoral fat pad
ligaments of cooper
describe the pectoral fat pad
determines the shape and size of the breast
gives the texture
makes up most of the breast tissue
describe coopers ligaments
- support the breasts
- become less supportive with age and hormones in pregnancy
each breast contains ________ lobes, each made up of milk-secreting _______.
15-20, lobules
each of the lobules connects to a single __________ ____
lactiferous duct
what is the lactiferous sinus?
an expansion of the lactiferous duct that opens onto the nipple to allow extraction of milk
when do aveoli develop in the breast?
only after puberty and under the influence of oestrogen
how much of the breast tissue is alveoli?
a small amount in comparison to the fat and duct system
why do humans develop major mammary glands before pregnancy and most other animals dont?
due to the menstrual cycle and oestrogen and progesterone promoting the growth of alveolar buds, where sucessive cycles cause increased growth
what are the noticeable premenstrual changes in the breast?
increase in volume of the breast and tenderness
which component of the breast grows the most during pregnancy?
alveolar tissue
ostrogen is essential for?
breast growth
progesterone induces?
side branching of ducts
prolactin is necessary for?
areolar development, but also stimulates casein and alpha-lactalbumin production for breast milk
what do insulin and cortisol do in the breast?
stimulate alveolar epithelial cell division to develop glandular tissue
what is the main noticeable difference between a lactating and resting breast under histology?
lactating will have lots of alveoli compared to resting
describe breast size at pregnancy and lactation
2-3x near term pregnancy
3-4x lactating
what hormone allows lactation not to happen until after birth?
progesterone (and oestrogen) prevents milk production
it also relaxes smooth muscle to prevent milk ajection
what hormone is released by the anterior pituitary in response to a baby’s suckling?
prolactin
which reflex can cutting the nerves to the nipple prevent?
the neuroendocrine reflex of baby suckling causing prolactin secretion
describe the milk production response
more suckling induces more prolactin secretion from the anterior pituitary and leads to more milk, so the baby decides how much milk it needs
what is the milk ejection response?
happens in response to oxytocin release by the posterior pituitary, and induces the contraction of the myoepithelial cells of the alveoli, causing ejection of the milk into the ducts
what can cause the MER?
stimulation of female reproductive tract (sex)
environmental stimuli such as crying baby or baby smell
what other hormones does prolaction suppress the secretion of?
FSH and LH, mostly LH
- and so lactating women have either irregular or no menstrual cycles - contraceptive effect
benefits of breastfeeding to mother?
less cancer risk
lactation is protective against development of breast cancer
benefits to the infant of breastfeeding?
protection from GI infection
less obesity
protective against diabetes and SIDS
bottle fed babies are often ________, while breastfeed babies are often _______.
overweight, healthy weight
what are supernumerary nipples/breasts?
additional breasts or nipples, usually occur along the line of the embryonic milk ridge. additional lactiferous ducts can also happen (may want to add)
