breast

Question 1

what are the purposes of the breast?

Answer 1

1. nutrition of the young

2. spacing of pregnancies e.g. contraceptive

Question 2

derivation of the breast

Answer 2

• mammary glands are modified sweat glands
• they’re derived from tissue that is first identified in the mammary (or milk) crests that arise between the axilla and the groin
• breast development begins with the formation of mammary buds at about 6 weeks

Question 3

first development of the breast

Answer 3

takes place as a down growth of the dermis to form the primary breast bud

secondary buds develop from the primary bud
-they become the lactiferous ducts

Question 4

canalisation

Answer 4

under the influence of hormones e.g. P4 and E2, as gestation progresses the buds develop lumens (become canalised)

is induced by placental steriods (P4 and E2)

Question 5

lactiferous ducts at birth

Answer 5

by birth 15-20 lactiferous ducts are present

Question 6

when are breast fully developed and could potentially make milk

Answer 6

at birth

milk production would require hormonal stimulus

because the fetus has been exposed to the placental steroids and maternal hormones at birth some babies do make a colostrum-like secretion called witch’s milk

Question 7

increase in male breast tissure

Answer 7

gynaecomastia

Question 8

structure of the nipple

Answer 8

raised (usually) cyclindrical pigmented structure

can be inverted

the lacterferous ducts join the skin at the nipple

Question 9

structure of the areola

Answer 9

pigmented circle of tissue surrounding the nipple

contains sebaceous glands which give a granular texture to the surface

Question 10

internal structures of the breast

Answer 10

major component = adipose tissue of the pectoral fat pad

breasts are supported by ligaments = suspensory ligaments of cooper

Question 11

lobes within the breast

Answer 11

human breast contains 15-20 lobes each made up of milk-secreting lobules

each lobules connect to a signle lactiferous duct

these structures look a little like a bunch of grapes

Question 12

estrogens effect on the breast

Answer 12

causes cell growth of epithelial cells that make up the milk producing alveoli within the lobules

Question 13

menstrual cycle and the breast

Answer 13

estrogen and progesterone promote the growth of the alveolar buds - successive cycles cause increased growth

Question 14

estrogen essential for…

Answer 14

breast growth

Question 15

progesterone induces

Answer 15

side branching of ducts

Question 16

prolactin

Answer 16

necessary for alveolar development but also stimulates casein and causes milk production

produced in large amounts in pregnancy and falls at birth

Question 17

hormones cause

Answer 17

the expansion of the alveoli and ductile system. The ducts grow, branch and bud

Question 18

lactational amenorrhea

Answer 18

Is the temporary postnatal infertility that occurs when a woman is amenorrheic (not menstruating) and fully breastfeeding.

lactational amenorrhea can last for 9 months

• it is an effective form of contraception in some women
• is entirely unpredictable

Question 19

progesterone prevents

Answer 19

major milk production

is a smooth muscle relaxant and prevents milk ejection
no ejection of milk during pregnancy

Question 20

what induces the secretion of prolactin

Answer 20

suckling of the infant on the nipple induces secretion of prolactin by the anterior pituitary (outside of pregnancy)

secretion is stimulated by a neuroendocrine reflex
-cutting the nerves to the nipple prevents this reflex

Question 21

endocrine control of lactation

Answer 21

suckling causes reduced secretion of dopamine (prolactin inhibiting factor) into the portal blood

concurrently vasoactive intestinal peptide (VIP) secretion by the paraventicular nuclei is increased

both factors act on the lactotrophs to secrete prolactin

prolactin induces production of milk proteins

amount of suckling is proportional to the amount of prolactin secreted

Question 22

milk ejection response

MER

Answer 22

suckling also stimulates synthesis and secretion of oxytocin by the posterior pituitary

oxytocin induces the contraction of the myoepithelial cells of the alveoli causing ejection of the milk into the ducts

Question 23

factors that induce the MER

Answer 23

• stimulation of the female reproductive tract can induce oxytocin release
  during sex
• crying of baby
• smell of baby

Question 24

supernumeroury nipples/breasts

Answer 24

• usually found along the line of the embryonic milk ridge
• additional nipples can occur on the breast or along the milk ridge and lactiferous ducts can exit the breast at sites outside the nipple