Developmental biologyLesson 3 of 4 in the course Development and Inheritance

Neonatal Transition: Birth Circulation, Thermoregulation, Feeding, and Apgar

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

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Summary

Birth requires an infant to move rapidly from a fetal system supported by the placenta to independent breathing and circulation. This lesson explains how the first breath starts these changes and how fetal blood vessels and shunts are altered after birth.

In the uterus, the fetus does not breathe air. The placenta supplies oxygen and removes carbon dioxide, while the partially collapsed lungs are filled with amniotic fluid and have little metabolic activity. Fetal breathing movements may occur, but they do not provide the gas exchange needed after birth.

All flashcards

What prompts the newborn’s first breath?
Reduced oxygenated blood flow during labor allows carbon dioxide to rise; the resulting acidosis stimulates the brain’s respiratory center.
What changes occur in the lungs during the first breaths?
Alveoli open, surrounding capillaries fill with blood, and lung fluid drains or is absorbed, enabling gas exchange.
What is brown fat’s role in newborn thermoregulation?
Its metabolism produces heat without shivering; specialized mitochondria release less energy as ATP and more as heat.
What does the ductus venosus become after birth?
It becomes the ligamentum venosum.
Which five criteria make up the Apgar score?
Appearance, pulse, grimace, activity, and respiration.

Quiz questions

  1. How does brown fat help a newborn produce heat without shivering?Answer: Its metabolism releases energy as heat rather than storing as much of it in ATP.
  2. Which findings are assessed in the Apgar score?Answer: Appearance, pulse, grimace, activity, and respiration.
  3. How is an Apgar score calculated and when is it routinely recorded?Answer: Five criteria receive 0–2 points each; the total is recorded at 1 and 5 minutes after birth.
  4. Why is fluid intake from breast milk or formula important for newborns?Answer: Immature kidneys produce dilute urine and cannot concentrate it efficiently, increasing water loss.
  5. What is one effect of a newborn’s first breast milk or formula on the intestine?Answer: It introduces beneficial bacteria that begin establishing intestinal flora.

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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