A rise in the blood level of carbon dioxide is called:

A. Asthma is not typically linked to bedrest. Bedrest can lead to decreased lung expansion and impaired mucus clearance, which may increase the risk of infections like pneumonia, but it does not specifically increase the risk of asthma.
B. When a patient is immobile and unable to get out of bed, mucus can accumulate in the lungs, as normal coughing and deep breathing are reduced. This pooling of mucus provides an ideal environment for bacteria to grow, leading to pneumonia.
C. While supplemental oxygen might be needed for patients with certain respiratory conditions, it is not the primary risk factor for pneumonia in bedrest. In fact, oxygen therapy might be used to treat pneumonia.
D. Hospital-acquired infections, including pneumonia, are a concern, but the primary risk from bedrest is the inability to clear mucus effectively, not the presence of pathogens alone.

A. The internal exchange of gases occurs at the tissue level, where oxygen is delivered to cells and carbon dioxide is removed. The diaphragm is not involved in this process.
B. Exhalation involves the relaxation of the diaphragm, which causes the lungs to compress and air to be expelled from the lungs.
C. During inhalation, the diaphragm contracts and moves downward, creating more space in the chest cavity, which allows the lungs to expand and air to flow in.
D. The external exchange of gases occurs in the lungs, where oxygen is transferred into the blood and carbon dioxide is removed, but it is not directly linked to diaphragm contraction.