Final answer:
The human lung cells affected by Mycobacterium tuberculosis in tuberculosis are alveolar macrophages. Tuberculosis leads to the formation of tubercles and lung tissue damage. Smoking increases susceptibility to TB due to impaired lung immune functions.
Step-by-step explanation:
When Mycobacterium tuberculosis bacteria damage human lung cells causing tuberculosis (TB), the specific cells in the lungs that are affected are the alveolar macrophages. These macrophages are responsible for engulfing and attempting to destroy the bacteria. However, M. tuberculosis has adapted to survive and multiply within these immune cells. Tuberculosis is a disease characterized by the formation of granulomas, or tubercles, within lung tissue. Over time, the persistent immune response can lead to lung tissue damage and the induction of apoptosis, creating caseous centers where the bacterium can thrive.
Furthermore, smoking increases the risk of developing TB as it impairs lung immune functions such as phagocytosis and the action of antimicrobial peptides. It is also crucial to note that M. tuberculosis is an acid-fast, high G + C, gram-positive bacillus with a waxy cell wall, which aids its survival inside macrophages. The infectious dose of M. tuberculosis is quite low, requiring only around 10 bacteria to potentially establish an infection.