Name a common cause of respiratory acidosis.

Hypoventilation is a common cause of respiratory acidosis because it leads to an accumulation of carbon dioxide (CO2) in the bloodstream. When a person hypoventilates, they do not exhale enough CO2, resulting in increased levels of CO2 in the body, which subsequently causes the blood's pH to decrease, leading to acidosis. This condition can occur in various scenarios, such as respiratory conditions that impair lung function, central nervous system depression, or obstructions in the airway, all of which can hinder proper ventilation.

In contrast, hyperventilation typically results in decreased levels of CO2 and can lead to respiratory alkalosis, where the blood becomes too alkaline. Normal breathing maintains a balance in CO2 and oxygen levels and does not contribute to acidosis or alkalosis. High altitudes may cause respiratory difficulties but primarily lead to hypoxia or respiratory alkalosis due to hyperventilation in response to lower oxygen levels rather than causing acidosis. Thus, hypoventilation stands out as a direct mechanism that causes respiratory acidosis through CO2 retention.