What is meant by the term placenta?
Reveal answer
Temporary exchange organ linking maternal supply to the fetal circulation.
Key words: placenta
4(a) REPRODUCTION · RECALL
4.11 The placenta
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What is meant by the term chorionic villus?
Reveal answer
Branching fetal placental projection containing capillaries.
Key words: chorionic villus
What is meant by the term umbilical cord?
Reveal answer
Cord containing vessels connecting fetus and placenta.
Key words: umbilical cord
What is meant by the term placental barrier?
Reveal answer
Thin layers separating maternal and fetal blood.
Key words: placental barrier
Placental transport: for Oxygen, give the direction and the importance.
Reveal answer
Direction: Mother → fetus. Importance: Aerobic respiration.
Key words: Oxygen
Placental transport: for Glucose/amino acids, give the direction and the importance.
Reveal answer
Direction: Mother → fetus. Importance: Respiration, growth and biosynthesis.
Key words: Glucose/amino acids
Placental transport: for Carbon dioxide, give the direction and the importance.
Reveal answer
Direction: Fetus → mother. Importance: Removal by maternal lungs.
Key words: Carbon dioxide
Placental transport: for Urea, give the direction and the importance.
Reveal answer
Direction: Fetus → mother. Importance: Removal by maternal kidneys.
Key words: Urea
Placental transport: for Umbilical vein, give the direction and the importance.
Reveal answer
Direction: Placenta → fetus. Importance: Carries relatively oxygenated blood.
Key words: Umbilical vein
Placental transport: for Umbilical arteries, give the direction and the importance.
Reveal answer
Direction: Fetus → placenta. Importance: Carry relatively deoxygenated, waste-rich blood.
Key words: Umbilical arteries
True or false, and why? “Maternal and fetal blood normally mix in the placenta.”
Reveal answer
False. They flow close together but remain in separate circulations.
True or false, and why? “The umbilical artery carries oxygenated blood because arteries always do.”
Reveal answer
False. Arteries carry blood away from a heart; fetal umbilical arteries carry blood towards the placenta.
True or false, and why? “The placenta blocks every harmful substance.”
Reveal answer
False. Alcohol, nicotine, some drugs and pathogens can cross.
Name two substances that pass from the fetus to the mother across the placenta.
Reveal answer
Carbon dioxide and urea.
Key words: carbon dioxide · urea
Name two harmful substances that can cross the placenta.
Reveal answer
Alcohol, nicotine, some drugs, some viruses (any two).
Key words: alcohol