Question 1

What is the positive-feedback mechanism during parturition?

Accepted Answer

Stretch of the cervix and foetal membranes activates a reflex that signals hypothalamic neurons; oxytocin is synthesised in the hypothalamus and released from the maternal posterior pituitary. Oxytocin strengthens uterine contractions, which increase stretch and cause still more oxytocin release until birth is completed.

Question 2

How much does the cervix dilate at full dilatation?

Accepted Answer

The cervix dilates to approximately 10 cm at full dilatation. This allows the foetus to pass through the birth canal, and the placenta is delivered or expelled after the foetus.

Question 3

How do prolactin and oxytocin differ in lactation?

Accepted Answer

Prolactin from the anterior pituitary regulates mammary gland growth and the formation of milk. Oxytocin released from the maternal posterior pituitary causes milk ejection by contracting smooth muscles around the alveoli, moving milk through the ducts toward the nipple.

Question 4

What is colostrum and why is it important for a newborn?

Accepted Answer

Colostrum is the first milk produced during the initial few days of lactation. It is yellowish and especially rich in antibodies such as IgA, providing passive immunity to the newborn before its own immune system matures.

Question 5

Does oxytocin produce milk or eject already-made milk?

Accepted Answer

Oxytocin does not produce milk. It causes milk ejection, or let-down, by moving already-formed milk from the alveoli through the ducts to the nipple. Prolactin is the hormone responsible for milk production.

Parturition & Lactation 3D — Oxytocin, Milk Ejection & Colostrum

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