Final answer:
Pneumonia leads to fluid-filled alveoli, preventing gas exchange in the lungs and causing symptoms such as coughing, chest pain, and breathing difficulties.
Step-by-step explanation:
A respiratory infection like pneumonia can severely affect the exchange of gases between the alveoli in the lungs and the surrounding capillaries. During pneumonia, the alveoli become filled with fluid, which inhibits gas exchange by preventing oxygen from entering the blood and carbon dioxide from being expelled. The capillaries surrounding the alveoli cannot effectively exchange gases because of the fluid barrier, leading to symptoms like coughing, chest pain, and difficulty breathing. Moreover, the presence of inflammatory cells and debris due to the infection can further escalate this impairment, aggravating the patient's condition.