(a)[3]
Use a label line and the correct letter to identify each of the following on Fig. 4.1: W right atrium X tricuspid valve Y aorta.
(b)[3]
Starting at the left ventricle, describe the route blood follows on its journey to the lungs.
(c)[4]
Describe and explain how the structure of the human gas exchange surface is adapted to work as efficiently as possible.