Lung diseases

Pulmonary tuberculosis (TB):
TB is a lung disease caused by the bacterium Mycobacterium tuberculosis.

Infection -
When someone becomes infected with this bacteria, immune system cells build a wall around the bacteria in the lungs.
This forms small, hard lumps known as tubercles.
Infected tissue within the tubercles dies and the gaseous exchange surface is damaged, so tidal volume is decreased.
Tuberculosis also causes fibrosis which further reduces the tidal volume. If the bacteria enters the bloodstream, they can spread to other parts of the body.

Symptoms -
Common symptoms include a persistent cough, coughing up blood and mucus, chest pains, shortness of breath and fatigue.
Sufferers may also have a fever and many lose weight due to a reduction in appetite.
Many infected people are asymptomatic - they're infected but don't show symptoms as the infection is in an inactive form. They cannot pass on the infection but if they become weakened, by another disease or malnutrition, the infection can become active so they would start showing symptoms and be infectious.

Transmission -
It is transmitted by droplet infection - when an infected person coughs or sneezes, tiny droplets of saliva and mucus containing the bacteria are released from their mouth and nose. If these droplets are breathed in, others will become infected.
It tends to be more widespread in areas of poor hygiene and crowded conditions. 
It can be prevented with the BCG vaccine and treated with antibiotics.

Fibrosis:
It is the formation of scar tissue in the lungs, as the result of an infection or exposure to substances like asbestos or dust.
Scar tissue is thicker and less elastic than normal lung tissue. This means that the lungs are less able to expand so can't hold as much air…