Final answer:
A partial blockage of the trachea causes inadequate ventilation, leading to increased carbon dioxide levels and decreased oxygen levels in the alveoli, which results in an impaired gas exchange known as V/Q mismatch.
Step-by-step explanation:
When a partial blockage of the trachea occurs, it leads to inadequate ventilation, which in turn disrupts the efficient exchange of gases in the alveoli. The result is a reduced clearing of carbon dioxide (CO2) and a lesser intake of oxygen. Since the alveoli are not being ventilated properly, the concentration of CO2 in the alveolar air increases because it is not being removed as efficiently by exhalation. Meanwhile, oxygen that normally fills the alveoli when we inhale is not replenishing the supply, causing a decrease in the partial pressure of oxygen. This imbalance, known as a V/Q mismatch, affects gas exchange and can result in decreased oxygen levels in the blood and increased CO2 levels.