Question

External respiration involves the movement of O2 in which of the following ways?

1) Diffusion across the respiratory membrane
2) Active transport by red blood cells
3) Transport by the circulatory system
4) All of the above

Answer 1

External respiration primarily involves the passive process of diffusion across the respiratory membrane, facilitated by partial pressure gradients, and is not associated with active transport by red blood cells.

Step-by-step explanation:

External respiration involves the movement of oxygen (O2) through different processes:

1. Diffusion across the respiratory membrane from the alveolus to the capillary.
2. Active transport is not part of this process; instead, O2 binds to hemoglobin in red blood cells passively.
3. Transport by the circulatory system to deliver oxygen throughout the body.

The external respiration occurs when there is a partial pressure gradient between the alveoli in the lungs and the blood in the pulmonary capillaries, allowing oxygen to move into the blood and carbon dioxide to be released from it.