The lungs are the organs responsible for the exchange of oxygen and carbon dioxide between the air and the blood via the bronchial tree. Tuberculosis (TB) is a granulomatous disease which primarily infects the lungs but can spread to other vital organs. It is caused by bacteria called Myobacterium tuberculosis and if went untreated, can be fatal. TB is spread through the air when a person who is infected coughs or sneezes and a person nearby breathes the air. People who have been diagnosed with HIV are at a higher risk of contracting TB since their immune systems are weaker. Other risk factors include having diabetes, use of alcohol and drugs. In this paper I will discuss the normal functions and anatomy of the lungs and how TB effects these functions.
The lungs are located in the thoracic cavity above the diaphragm. They are large and cone-shaped in which the tip of the organs are called the apex. The anterior surface of the lungs is called the costal surface, the medial surface is called the mediastinal surface and the base is called the diaphragmatic surface. Both lungs are divided into lobes, lobules, and segments. The right lung has three lobes called the superior, middle, and inferior lobes. They are separated by the horizontal and oblique fissures. On the medial surface there is point called the hilus where the bronchi and blood vessels enter and leave. The left lung, being smaller, has two lobes called the superior and inferior lobes. They are separated by the oblique fissure.
Each lung is actually a composition of 150 million alveoli. There are two types of alveolar cells; squamous (Type I) and great (type II). Squamous alveolar cells cover 95% of the surface area of an alveolus while great alveolar cells only cover 5%. However great alveolar cells are more numerous than squamous alveolar cells. Squamous cells are responsible for the rapid diffusion of gases between the air and blood. Great cells repair alveolar tissues and secrete a substance to coat alveoli and bronchioles.
There are two types of Tuberculosis: Latent TB infection and TB disease....