B8W3 Med Quiz

Breast anatomy: what drains into what

• lobule drains into ductule

• 15-20 ductules drains into lactiferous duct

• lactiferous duct drains into ampulla

contents of breast milk

• sugar (lactose)

• protein (lactalbumin +casein)

• fats (emulsion of fats in aqueous solution)

• Cations (K, Ca2+, Na)

• Anions (Cl-, phosphate)

mammogenic control of lactation

• what is does

• what hormones does it use

• what is does- promote proliferation of alveolar + duct cells

• what hormones does it use- progesterone + estradiol

lactogenic control of lactation

• what is does

• what hormones does it use

• what is does- initiate milk production by alveolar cells

• what hormones does it use- prolactin, placental lactogen, progesterone withdrawal +dopamine withdrawal

galactokinetic control of lactation

• what is does

• what hormones does it use

• what is does- milk ejection

• what hormones does it use- oxytocin

galactopoietic control of lactation

• what is does

• what hormones does it use

• what is does- milk production

• what hormones does it use- prolactin

what triggers the release of prolactin during lactation

suckling

what effect does TRH have on milk production

it increases milk production (by activating prolactin)

What effect does estradiol have on the sensitivity to TRH and DA

• TRH- increases sensitivity to stimulation

• DA- decreases sensitivity to inhibition

during the first 3 weeks of neonatal period are prolactin levels low or high

they remain elevated but eventually drop

what is the let down reflex

when oxytocin from the posterior pituitary induces release of pre-existing milk

What hormone stimulates contraction of myoepithelial cells surrounding the alveoli and ducts

oxytocin

Steps in lactation

1. suckling stimulus travels to hypothalamus through the spinal cord afferent pathway

2. dopamine release from the arcuate nucleus is inhibited but prolactin is released from the anterior pit

3. oxytocin from the paraventricular + supraoptic nuclei is released from the posterior pit

4. spinal cord neurons inhibit arcuate nucleus + preoptic neurons, this decreases GnRH and inhibits ovarian cycle (no period)

how does breast feeding delay ovulation +menstruation

suckling inhibits GnRH release (which is needed for mentstruation)

what effect does stress/fear have on oxytocin

they inhibit oxytocin