Describe the functions of the placenta and amniotic fluid, and explain the importance of the placental barrier.

3.3.1 a) Foetus: C b) Umbilical cord: B 3.3.2 One function of amniotic fluid (A): • It protects the fetus from mechanical shock or injury. • It maintains a constant temperature for the fetus. • It allows for fetal movement and development. • It prevents adhesion of fetal parts to the amnion. 3.3.3 Region D (placenta) serves as a barrier between the growing foetus and the mother. Two reasons why this barrier is necessary: • It prevents the mixing of maternal and fetal blood, which may have different blood groups or pressures, avoiding immunological reactions. • It protects the fetus from certain harmful substances (e.g., toxins, some pathogens, drugs) that may be present in the mother's blood. • It prevents the mother's immune system from attacking the fetus as a foreign body. 3.3.4 | Feature | Blood moving from the mother to region D (maternal arterial blood) | Blood going from region D to the mother (maternal venous blood) | | :---------------- | :----------------------------------------------------------------- | :--------------------------------------------------------------- | | Oxygen content | High | Low | | Nutrient content| High | Low | | Waste content | Low | High | 3 done, 2 left today. You're making progress.