Reproduction Part 4: Parturition and Lactation

Flashcards covering the stages of parturition, hormonal regulation, pharmacology of uterine smooth muscle, and lactation.

What is parturition?

The process of giving birth, occurring around 40 weeks of pregnancy.

What is lactation?

The production of milk in the mammary glands.

What is the typical position of the fetus before birth?

Head-first on the cervix.

What is the first stage of labor characterized by?

Dilation of the cervical canal to accommodate the fetus.

How much dilation of the cervix is required to accommodate the fetus's head?

10 cm

What is the amniotic sac rupture commonly referred to as?

'Waters breaking'

What happens during the second stage of labor?

The baby is delivered after complete cervical dilation.

What happens to the umbilical cord after the baby is delivered?

It is tied and then severed.

What occurs during the third stage of labor?

The placenta is expelled through myometrial contractions.

What are the two consequences of a newborn's inspiration of air following delivery?

Elevated O2 levels in fetal circulation and fetal supply of O2 to placental circulation.

What is the regulator of parturition?

The positive feedback loop of parturition.

What hormone causes uterine contractions?

Oxytocin from the posterior pituitary.

Where does the signal that triggers parturition come from?

The fetus

What is the principal source of placental Corticotrophin Releasing Hormone (CRH)?

The placenta

How do therapeutic agents modify uterine muscle activity?

By increasing intracellular calcium (spasmogen) or cyclic AMP (tocolytics).

What is the function of spasmogens?

Increase force and frequency of contractions

What are some clinical uses of spasmogens?

Induce or augment labor, control post-partum uterine hemorrhage, induce therapeutic abortion.

What is the function of relaxants (Tocolytic agents)?

Reduce frequency and force of contractions.

What are some clinical uses of relaxants (Tocolytic agents)?

Delay or prevent premature parturition.

What hormones stimulate and inhibit lactation?

Prolactin and Oxytocin stimulate lactation. Estrogen and Progesterone inhibit lactation.

What is colostrum?

Watery milk produced in the first few days after birth, containing proteins and few nutrients.

What does prolactin and oxytocin stimulate?

Prolactin stimulates milk synthesis, and Oxytocin stimulates the milk ejection reflex.

What are the advantages of breast feeding for the mother?

Oxytocin release hastens uterine involution and Suckling suppresses menstrual cycle by inhibiting LH and FSH secretion.

Why does milk production stop at weaning?

Absence of suckling means prolactin secretion is not stimulated and there is no oxytocin release to cause milk letdown.