In vertebrates with a double-loop circulation as illustrated in Figure 27–4, the loop that passes through the lungs is responsib
le for: A. exchanging carbon dioxide for oxygen from the air.
B. exchanging oxygen for carbon dioxide from the air.
C. delivering oxygen-rich blood to the body.
D. delivering oxygen-poor blood to the heart.
A. exchanging carbon dioxide for oxygen from the air.
Explanation:
In a double circulation, the blood circulates between the heart and lungs is known as a pulmonary circuit. This circuit transports deoxygenated blood to the lungs through the pulmonary artery to the lungs. Gaseous exchanges happens within the lungs. Carbon dioxide diffuses from the blood into the air within the alveoli and oxygen diffuses from the alveoli into the blood.
The correct answer among the choices provided is option A. Lung capillaries are responsible for exchanging carbon dioxide for oxygen from the air. Blood that comes from the heart gets oxygen from the alveoli. The carbon dioxide in the blood goes into the alveoli at the same time.
