MRCP UK EXAMINATIONS

Detailed explanation-1: -When TB bacilli are inhaled, they rapidly pass through the mouth and nose and pass into the lowest and smallest parts of the airways. They move into the terminal bronchioli and alveoli of the lung.

Detailed explanation-2: -The process of becoming infected with TB begins when inhaled TB bacteria, also known as tubercle bacilli, begin to multiply in the small air sacs of the lungs. Some TB bacteria then enter the bloodstream and spread throughout the body.

Detailed explanation-3: -Tuberculosis (TB) infection can develop after breathing in droplets sprayed into the air from a cough or sneeze by someone infected with the Mycobacterium tuberculosis bacterium. The resulting lung infection is called primary TB. The usual site of TB is the lungs (pulmonary TB), but other organs can be involved.

Detailed explanation-4: -Lung tissue is usually very thin and almost sponge-like because it is filled with air in the alveoli, where oxygen is exchanged from the air into the blood. The lung tissue affected by TB bacilli first becomes hard, making the oxygen exchange impossible. This is called fibrosis.

Detailed explanation-5: -The primary site of infection in the lungs, known as the Ghon focus, is generally located in either the upper part of the lower lobe, or the lower part of the upper lobe. Tuberculosis of the lungs may also occur via infection from the blood stream.