To address the statements based on the provided table of partial pressures of gases in different compartments, let's examine each statement carefully.
### Statement 1: [tex]\( O_2 \)[/tex] diffuses from tissues to oxygenated blood.
For oxygen to diffuse from one area to another, it must move from a region of higher partial pressure to a region of lower partial pressure. According to the table, the partial pressure of oxygen in the tissues is less than 30 mmHg, whereas in oxygenated blood, it is 100 mmHg. This indicates that oxygen would actually diffuse from the oxygenated blood (where its partial pressure is higher) to the tissues (where its partial pressure is lower). Therefore, the statement is:
False.
### Statement 2: [tex]\( CO_2 \)[/tex] diffuses from deoxygenated blood to alveoli in the lungs.
For carbon dioxide to diffuse, it must move from a higher to a lower partial pressure. According to the table, the partial pressure of [tex]\( CO_2 \)[/tex] in deoxygenated blood is 46 mmHg, while in alveolar air, it is 40 mmHg. This indicates that [tex]\( CO_2 \)[/tex] will diffuse from the deoxygenated blood (where its partial pressure is higher) to the alveoli (where its partial pressure is lower). Therefore, the statement is:
True.
### Statement 3: The partial pressure of oxygen in expired air is lower than the partial pressure of inspired air because tissues have used up some of the oxygen.
According to the table, the partial pressure of oxygen in inspired air is 160 mmHg, while in expired air, it is 116 mmHg. The reduction in the partial pressure of oxygen is due to the fact that some oxygen is used by the tissues during the process of respiration. Therefore, the statement is:
True.
### Statement 4: [tex]\( CO_2 \)[/tex] diffuses from tissues to oxygenated blood.
For carbon dioxide to diffuse, it must move from a higher to a lower partial pressure. The table shows that the partial pressure of [tex]\( CO_2 \)[/tex] in the tissues is greater than 50 mmHg, while in oxygenated blood, it is 40 mmHg. Since the partial pressure of [tex]\( CO_2 \)[/tex] is higher in the tissues, it will diffuse to the deoxygenated blood, not the oxygenated blood. Therefore, the statement is:
False.
### Summary of statements:
1. [tex]\( O_2 \)[/tex] diffuses from tissues to oxygenated blood. → False
2. [tex]\( CO_2 \)[/tex] diffuses from deoxygenated blood to alveoli in the lungs. → True
3. The partial pressure of oxygen in expired air is lower than the partial pressure of inspired air because tissues have used up some of the oxygen. → True
4. [tex]\( CO_2 \)[/tex] diffuses from tissues to oxygenated blood. → False
These answers match the detailed explanations provided.
