Video Transcript
The figure shows a fetus just
before birth. What is the role of the pituitary
hormone oxytocin in the birth process? (A) It stimulates fetal
movement. (B) It increases blood supply to
the placenta. (C) It stimulates uterine
contractions. Or (D) it stimulates contractions
in the cervix.
The diagram that the question
provides us with shows a fetus that is ready to be born. And the question asks us to
determine the role of the hormone oxytocin in this birthing process. To work this out, let’s first label
as much as we can on the diagram we’ve been provided with.
The fetus, which is the final stage
of development of a baby during pregnancy, develops within the mother’s uterus,
which is surrounded by a thick muscular uterine wall. We can also see the placenta in
this diagram, which is a temporary organ that develops in the uterus during
pregnancy to provide oxygen and nutrients to the growing fetus from the mother’s
blood and remove waste products from the fetal blood.
At the base of the uterus is a
region of tissue called the cervix. The cervix leads into a muscular
tract called the vagina, which is not quite visible on this diagram but would be
located just below the cervix.
Hormones play a crucial role over
the whole duration of pregnancy, as well as during childbirth, which is sometimes
known as parturition or labor. One such hormone that is involved
in the birth process is released from the pituitary gland in the brain and is of
interest to us in this question: oxytocin. When the fetus is ready to be born,
the uterus and cervix stretch, which stimulates the release of oxytocin. Oxytocin helps to induce
contractions of the muscle in the uterine wall at regular intervals. These contractions push the fetus
out of the uterus through the cervix and vaginal canal, allowing it to exit the
mother’s reproductive system and enter into the world.
Now we have enough information to
answer the question. The role of oxytocin in the birth
process is (C). It stimulates uterine
contractions.
