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.
The terminal bronchi and alveoli are located at the very end of the conducting zone and the beginning of the respiratory zone in the respiratory system. The bronchi (or bronchus) are the air passages into the lungs that begin at the end of the trachea.