1.34. Respiratory System Diseases http://www.ck12.org
FIGURE 1.62
A public health notice from the early 20th century reminded people that
TB could be spread very easily.(including coughing up blood), and weight loss. The most common cause of lung cancer is exposure to tobacco
smoke.
FIGURE 1.63
The inside of a lung showing cancerous tissue.Emphysema
Emphysemais a chronic lung disease caused by the breakdown of the lung tissue. Symptoms of emphysema include
shortness of breath, especially during exercise, and chronic cough, usually due to cigarette smoking, and wheezing,
especially during expiration. Damage to the alveoli (Figure1.64), is not curable. Smoking is the leading cause of
emphysema.
Causes of Respiratory Diseases
Many respiratory diseases are caused by pathogens. Apathogenis an organism that causes disease in another
organism. Certain bacteria, viruses, and fungi are pathogens of the respiratory system. The common cold and flu are