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.
left and right bronchi (-us: sing.) = primary bronchi cartilage in plates; submucosa with fewer sero-mucous glands; smooth muscle layer separates submucosa from lamina propria; lamina propria with lg quantity elastin superficially; respiratory epithelium fewer goblet cells; secondary or lobar bronchi.