Context: TB infection begins when the mycobacteria reach the pulmonary alveoli, where they invade and replicate within endosomes of alveolar macrophages. Macrophages identify the bacterium as foreign and attempt to eliminate it by phagocytosis. During this process, the bacterium is enveloped by the macrophage and stored temporarily in a membrane-bound vesicle called a phagosome. The phagosome then combines with a lysosome to create a phagolysosome. In the phagolysosome, the cell attempts to use reactive oxygen species and acid to kill the bacterium. However, M. tuberculosis has a thick, waxy mycolic acid capsule that protects it from these toxic substances. M. tuberculosis is able to reproduce inside the macrophage and will eventually kill the immune cell.

Question: What specific part of the lungs marks the start of tuberculosis infection?
Answer: pulmonary alveoli

Question: What's the process by which macrophages try to get rid of the TB bacterium?
Answer: phagocytosis

Question: What do you get when you combine a lysosome and a phagosome?
Answer: a phagolysosome

Question: What does the M. tuberculosis bacterium have that protects it from being affected by toxins?
Answer: mycolic acid capsule

Question: What vesicle is the temporary holding room for the M. tuberculosis bacterium during phagocytosis?
Answer: phagosome

Question: What replicates inside the pulmonary alveoli?
Answer: Unanswerable

Question: What begins when the endosomes reach the pulmonary alveoli?
Answer: Unanswerable

Question: What do the bacterium identify?
Answer: Unanswerable

Question: What envelopes the macrophage?
Answer: Unanswerable

Question: What does the combination of a lysosome and a phagolysosome create?
Answer: Unanswerable