Occupational Safety and Health Administration. 1  Department of Labor, Labor Department, DoL, Labor - the federal department responsible for promoting the working conditions of wage earners in the United States; created in 1913.
The oxygen and carbon dioxide exchange take place in the alveoli. Primary bronchi are located on the upper portion of the lungs, secondary bronchi is located at the center of the lungs and tertiary bronchi is located near bottom of the organs above the bronchioles.
Bronchi are plural for bronchus and represent the passageways leading into the lungs. A bronchus, which is also known as a main or primary bronchus, represents the airway in the respiratory tract that conducts air into the lungs. Bronchi will branch into smaller tubes that become bronchioles.