CLE Anatomy & Physiology of Lactation 2 — Questions and Answers
Question 1: Which hormone is primarily responsible for triggering milk ejection during breastfeeding?
- Prolactin
- Estrogen
- Oxytocin (Correct answer)
- Progesterone
Correct answer: Oxytocin
Oxytocin, released from the posterior pituitary, causes myoepithelial cells surrounding alveoli to contract and eject milk.
Question 2: What is the primary role of prolactin in lactation?
- Triggering milk let-down
- Stimulating milk synthesis in alveolar cells (Correct answer)
- Constricting mammary ducts
- Inhibiting oxytocin release
Correct answer: Stimulating milk synthesis in alveolar cells
Prolactin, secreted by the anterior pituitary, binds to receptors on alveolar epithelial cells to drive milk synthesis.
Question 3: During pregnancy, high levels of which hormones suppress full milk production despite rising prolactin?
- Oxytocin and cortisol
- Estrogen and progesterone (Correct answer)
- Insulin and glucagon
- FSH and LH
Correct answer: Estrogen and progesterone
Placental estrogen and progesterone block prolactin's action on alveolar cells, preventing full lactogenesis until after delivery.
Question 4: Which cells in the breast surround alveoli and contract in response to oxytocin?
- Adipocytes
- Fibroblasts
- Myoepithelial cells (Correct answer)
- Lactocytes
Correct answer: Myoepithelial cells
Myoepithelial cells are basket-like contractile cells that wrap around alveoli and squeeze milk into the ductal system when stimulated by oxytocin.
Question 5: Where is prolactin produced?
- Posterior pituitary gland
- Anterior pituitary gland (Correct answer)
- Hypothalamus
- Adrenal cortex
Correct answer: Anterior pituitary gland
Prolactin is produced by lactotroph cells in the anterior pituitary gland in response to suckling stimuli.
Question 6: What effect does dopamine have on prolactin secretion?
- It stimulates prolactin release
- It has no effect on prolactin
- It inhibits prolactin release (Correct answer)
- It converts prolactin to oxytocin
Correct answer: It inhibits prolactin release
Dopamine, also called prolactin-inhibiting factor (PIF), is released by the hypothalamus and tonically suppresses prolactin secretion.
Question 7: A mother reports that her milk 'lets down' just by hearing her baby cry. Which physiological process explains this?
- Increased prolactin from auditory stimulation
- Conditioned oxytocin reflex triggered by a sensory cue (Correct answer)
- Autocrine inhibition released by the sound
- Alveolar contraction from sympathetic stimulation
Correct answer: Conditioned oxytocin reflex triggered by a sensory cue
Oxytocin release can become conditioned to associated stimuli such as the baby's cry, sight, or smell, triggering the milk ejection reflex without direct nipple stimulation.
CLE Anatomy & Physiology of Lactation 2
Which hormone is primarily responsible for triggering milk ejection during breastfeeding?