In certain sections of the gas exchange system, cartilage is found so that the airways do not collapse when pressure changes during inhalation. State which parts of the gas exchange system contain cartilage.
Fig. 3.1 illustrates how atmospheric pressure and oxygen partial pressure vary with altitude. Using Fig. 3.1, describe how increasing altitude affects atmospheric pressure and the partial pressure of oxygen.
Calculate the change in atmospheric pressure when a person goes from sea level to an altitude of $3500\,\text{m}$. Show your working.
When a person travels from $0\,\text{m}$ (sea level) to a high altitude, lung gas exchange is affected. This can lead to hypoxia, in which the tissues of the body do not obtain enough oxygen. Explain how hypoxia develops when a person rises from sea level to a high altitude.
At high altitude, the body's short-term reactions to hypoxia include a smaller plasma volume in the blood, a lower volume of blood ejected by the heart per beat, a higher heart rate, and a higher breathing rate. Suggest why a decrease in plasma volume in the blood may reduce the effects of hypoxia.
Explain why heart rate increases in response to hypoxia.
Outline how this mutation may produce a changed amino acid sequence in the $\beta$-globin polypeptide.