Structures in the Amniotic Cavity

Question 1

Function of amniotic sac/membrane

Answer 1

Encloses the fetus in the amniotic cavity

Question 2

Function of amniotic fluid

Answer 2

1. Protects the fetus from mechanical shock
2. Allows the fetus to move around in the uterus
3. Maintains a constant temperature for the fetus

Question 3

Function of the placenta

Answer 3

1. Allows oxygen and dissolved nutrients such as glucose and amino acids to pass from the mother’s blood to the fetus’ blood via diffusion
2. Allows carbon dioxide and metabolic waste products such as urea to pass from the fetus’ blood to the mother’s blood via diffusion
3. Allows antibodies to pass from mother’s blood to the fetus’ blood (not via diffusion)

Question 4

Function of umbilical cord

Answer 4

1. Veins carry oxygenated blood with dissolved nutrients such as glucose and amino acids from the placenta to the fetus
2. Arteries carry deoxygenated blood with metabolic waste products such as carbon dioxide and urea from the fetus to the placenta

Question 5

Substances that can pass through the placenta

Answer 5

1. From mother to fetus
   - oxygen, dissolved nutrients (glucose,amino acids and fatty acids)
2. From fetus to mother
   - carbon dioxide, metabolic waste products (urea)

Question 6

Substances that cannot pass through the placenta

Answer 6

Red blood cells and plasma proteins ( too large to pass through the partially permeable capillary wall )