Final answer:
The apex of the lungs is more prone to hypoxic and hypercarbic conditions in an upright position. Hyperventilation results in increased blood pH and respiratory alkalosis. The right ventricle sends blood to the lungs for oxygenation.
Step-by-step explanation:
In an upright position, the apex (a) of the lungs is the region where the blood exhibits a lower level of oxygen (hypoxic) and higher level of carbon dioxide (hypercarbic) compared to the base. The gravitational effect leads to more blood being present at the base of the lungs, which is closer to the diaphragm, where gas exchange is more efficient. Conversely, at the apex, blood flow is less due to gravity, and thus the ventilation-perfusion ratio is lower, which results in relative hypoxia and hypercarbia compared to the base of the lungs.
Increased ventilation that leads to an increase in blood pH is called hyperventilation (a), not to be confused with hyperpnea, acclimatization, or apnea. Hyperventilation can cause respiratory alkalosis due to the excessive removal of carbon dioxide from the blood.
The right ventricle sends blood to the lungs (c) for oxygenation, which is then returned to the left side of the heart and pumped to the rest of the body.