<unk> typically enter the lung with inhalation, though they can reach the lung through the bloodstream if other parts of the body are infected. Often,<unk> live in parts of the upper respiratory tract and are continuously being inhaled into the alveoli, the cavities deep in the lungs where gas exchange takes place. Once inside the alveoli,<unk> travel into the spaces between the cells and also between adjacent alveoli through connecting pores. This invasion triggers the immune system to respond by sending white blood cells responsible for attacking microorganisms (neutrophils) to the lungs. The neutrophils engulf and kill the offending organisms but also release cytokines that result in a general activation of the immune system. This results in the fever, chills, and fatigue common in<unk>  and fungal pneumonia. The neutrophils,<unk>  and fluid leaked from surrounding blood vessels fill the alveoli and result in impaired oxygen transportation.<unk> can travel from the lung into the blood stream (bacteremia) and can result in serious illness such as sepsis and eventually septic shock, in which there is low blood pressure leading to damage in multiple parts of the body including the brain, kidney, and heart. They can also travel to the area between the lungs and the chest wall, called the pleural cavity.
Bacterial pneumonia
Viral pneumonia
Fungal pneumonia
Atypical pneumonia
Dust pneumonia
Community-acquired pneumonia
Aspiration pneumonia
Pneumococcal pneumonia