The lung consists of five lobes. The left lung has a superior and inferior lobe, while the right lung has superior, middle, and inferior lobes. Thin walls of tissue called fissures separate the different lobes.
Only the right lung has a middle lobe. As the name implies, this lobe is located between the upper and lower (also called the superior and inferior) lobes. Each lobe receives air from its own branch of the bronchial tree, called lobar (or secondary) bronchi. Within the lungs, these bronchi are divided into smaller tubes. The smallest of these tubes is called a bronchiole. Bronchioles control the exchange of gases with the alveoli, which are tiny air sacs in the lungs.
Each lobe of the lung has the same physiologic function, bringing oxygen into the bloodstream and removing carbon dioxide. Sections of a lobe, or even entire lobes can be removed as a treatment for conditions such as lung cancer, tuberculosis, and emphysema.