The respiratory system consists of the nose, pharynx, larynx, trachea, bronchi, and lungs. Its primary function is to provide oxygen to cells and remove carbon dioxide. External respiration is the exchange of gases in the lungs, while internal respiration is the exchange of gases at the cellular level. The respiratory system works with the circulatory system to oxygenate blood and remove carbon waste. Issues like pneumonia can cause inflammation and fluid buildup in the lungs. Monitoring vital signs like respiration rate helps assess a person's health status.