Fig. 4.1 shows a vertical section of the mammalian heart. The differences in the thickness of the cardiac muscle in the walls of the four chambers are shown. Explain, with reference to their functions, why the walls of the left ventricle and right ventricle differ in thickness.
The alveolus is the gas exchange surface in mammals. For efficient oxygen uptake, a steep diffusion gradient is kept between the alveolar air and the blood. Suggest how the steep diffusion gradient for oxygen is maintained at the gas exchange surface.
Compared with when they were non-smokers, the ability of people who smoke tobacco to deliver oxygen to their body tissues is reduced. Two reasons for this reduction are a smaller volume of air per breath moving towards the alveoli and a lower capacity of red blood cells to carry oxygen. Suggest one reason why smoking tobacco, even after only a short time, may reduce the volume of air per breath moving towards the alveoli.
Explain why smoking tobacco reduces the ability of red blood cells to carry oxygen.