PhysiologyLesson 4 of 7 in the course Development and Inheritance

Physiological Changes in Pregnancy, Labor, Birth, and Recovery

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

Pregnancy involves coordinated changes that support fetal development and prepare the body for birth. This lesson introduces how pregnancy is dated, how it is divided into trimesters, and how hormones change roles as pregnancy progresses.

A full-term pregnancy lasts approximately 270 days (38.5 weeks) from conception to birth. Because the date of conception is often difficult to know, health professionals generally calculate the due date from the first day of the last menstrual period (LMP). The estimated due date is about 284 days (40.5 weeks) after the LMP. This calculation assumes conception occurred around day 14 of a typical menstrual cycle.

All flashcards

What is the corpus luteum’s role early in pregnancy?
It supplies hormones, especially progesterone, that support the endometrium before the placenta is fully established.
How does the placenta produce estrogens during pregnancy?
It converts weak androgens from maternal and fetal adrenal glands into estrogens.
Why does a late-pregnancy decline in progesterone matter for labor?
It allows uterine contractions to become stronger as labor approaches.
What does relaxin do in preparation for birth?
It increases flexibility of the symphysis pubis and pelvic ligaments and helps the cervix dilate.
How does the myometrium become more responsive to oxytocin near labor?
It expresses more oxytocin receptors.

Quiz questions

  1. What does hCG do early in pregnancy?Answer: It supports the corpus luteum and stimulates male fetal gonads to produce testosterone.
  2. Which factors are thought to contribute to nausea and vomiting in early pregnancy?Answer: Pregnancy hormones and decreased intestinal peristalsis.
  3. By childbirth, approximately how much greater is blood volume than before conception?Answer: About 30 percent.
  4. Which pattern distinguishes true labor contractions from Braxton Hicks contractions?Answer: True labor contractions become regular and progressively stronger.
  5. How do oxytocin and prostaglandins reinforce labor contractions?Answer: Contractions promote prostaglandin release, which further strengthens contractions.

Based on Anatomy and Physiology 2e by J. Gordon Betts, Kelly A. Young, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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