Question

Why is parturition called a neuroendocrine mechanism? Explain.

Answer 1

Hint: The nervous system and endocrine system together form the neuroendocrine system which controls and coordinates the body functioning. A system of glands that secretes hormones for transport to target tissues is called the endocrine system. A system of specialized organs and nerves that control and coordinate activities of different organs and systems of the body is called the nervous system.

Complete answer:
Parturition is induced by a complex neuroendocrine mechanism. A fully formed fetus and the placenta together called the fetal ejection complex triggers parturition. A fetus secretes hormones from its adrenal glands that diffuse into the maternal blood and accumulate to release the oxytocin from the mother’s posterior pituitary. Oxytocin, also called birth hormone, is a peptide hormone that influences the working of smooth muscles.
Oxytocin causes the forceful myometrium contraction, called labor pain, which pushes the fetus gradually out through the dilated cervix (caused by relaxin) and vagina. In turn, uterine contraction stimulates further secretions of oxytocin. The stimulatory reflex between the oxytocin secretion and uterine contraction leads to stronger and stronger contractions. It is aided by a reflex and voluntary contraction of abdominal muscles whose center lies in the lumbar region of the spinal cord. In the beginning, the ejection reflex is mild, occurring at an interval of a quarter or half an hour, but soon becomes more frequent.
The expulsion stage lasts about 20 minutes to an hour during which fetal membranes burst and amniotic fluid is released but fetal membranes remain behind. It is followed by a placental stage, during which the umbilical cord, placenta, and fetal membranes are expelled after birth. This stage lasts for 10-45 minutes.
Parturition is controlled by two hormones:
1. Oxytocin: Causes endometrium to contract during parturition.
2. Relaxin: Relaxes the pubic symphysis of the pelvic girdles to widen the pelvis.
The above explanation clearly indicates that a partition is a neuroendocrine mechanism.

Note:
After childbirth, the placenta detaches, the uterus reduces in size. The umbilical cord is tied and then cut which becomes a depressed scar called umbilicus or navel. Sometimes, due to some complications, the fetus fails to come out, then the baby is delivered by a surgical procedure and the baby is called a cesarean.