Thinking and Investigating 1. Explain the role of the blood and the circulatory system in:
(a) The digestive system. (b) The respiratory system.
2. All babies in the womb have a hole in their heart between the right and left atrium. This hole means that blood flows from the right atrium into the left atrium. Blood does not flow to the lungs. This hole normally seals up shortly after the baby is born. Sometimes this hole does not seal up after birth and the baby is said to have ‘a hole in the heart’. (a) Why do you think a baby in the womb has this hole in his/her heart? (b) Why does the blood not need to flow to the baby’s lungs? (c) Why do you think this hole normally closes up shortly after birth? (d) If this hole does not close up after birth, what effect do you think it will have on the baby?
(e) How do you think doctors would fix this heart defect?
3. In a typical individual, 100 ml of blood holds 14 ml of oxygen, and the ventricles each have a volume of 70 ml. Given these data and what you have learned about the heart beat, calculate how much oxygen the blood absorbs from the lungs in one minute.
