Which body system is primarily affected by pneumonia?

Pneumonia primarily affects the respiratory system because it is an infection that inflames the air sacs in the lungs, which can fill with fluid or pus. This condition directly impacts breathing and the exchange of oxygen and carbon dioxide, making it a critical respiratory illness. The symptoms often include cough, fever, difficulty breathing, chills, and chest pain—all related to lung function.

The respiratory system's primary role is to provide the body with oxygen and remove carbon dioxide through the process of breathing. When pneumonia occurs, this vital function is compromised, leading to reduced oxygen availability for the body’s tissues and organs. While other body systems, such as the circulatory or nervous systems, can be indirectly affected due to the systemic nature of the infection, the lungs and the airways are undeniably at the forefront of the disease process associated with pneumonia.