The neck and abdominal muscles are involved in a:

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. Carbon dioxide does diffuse into the blood from the alveoli, but oxygen diffuses into the blood from the alveoli, not into the alveoli.
B. Oxygen diffuses from the alveoli into the blood where it binds to hemoglobin in red blood cells, while carbon dioxide diffuses from the blood into the alveoli to be exhaled.
C. Both oxygen and carbon dioxide do not diffuse from the alveoli into the blood at the same time. Only oxygen moves into the blood, and carbon dioxide moves in the opposite direction, from the blood to the alveoli.
D. While carbon dioxide moves from the blood into the alveoli, oxygen moves in the opposite direction, from the alveoli into the blood, so this answer is incorrect.