A diagram of the human lungs can depict different parts, including the alveoli, bronchi, pleura, diaphragm and bronchioles, notes WebMD.com. Although humans have two lungs, these organs are not identical because the right lung has three lobes and the left has two lobes. The lungs are important organs of the respiratory system, and their main function is to move oxygen into the bloodstream and remove carbon dioxide from the blood.
Other parts of the respiratory system that may appear on a lung diagram include the airway and muscles used for respiration, states InnerBody.com. Human respiration involves taking in the oxygen in air through the different sections of the airway passage, which includes the mouth, nostrils, pharynx, larynx and trachea. From the trachea, or windpipe, air enters each lung through two branch-like tubes called bronchi. Each bronchus subdivides into smaller, branch-like parts called secondary and tertiary bronchi, which divide further into much smaller branches called bronchioles.
At the end of the bronchioles are very small air sacs called alveoli, which is where gas exchange occurs. In the alveoli, oxygen is taken into the bloodstream and the carbon dioxide in blood moves into the alveoli for expulsion as a waste product through exhalation.
The lungs are sponge-like organs, and the pleura is a sheet of tissue or membrane that lines these organs. The right lung is larger than the left lung. The diaphragm, which is a muscular membrane, is necessary for breathing. When the diaphragm contracts and pulls in a downward position, the lungs expand to take in air. The exhalation process causes the diaphragm to relax.