Light microscopy typically shows neutrophils in bronchi, bronchioles and adjacent alveolar spaces. Crackles are often associated with inflammation or infection of the small bronchi, bronchioles, and alveoli. Bronchoconstriction is defined as the narrowing of the airways in the lungs (bronchi and bronchioles). The branching process forms the bronchi, bronchioles, and ultimately the alveoli. There are oxygen sensors in the smaller bronchi and bronchioles. The bronchial arteries supply blood to the bronchi and connective tissue of the lungs. Bronchial adenomas are adenomas in the bronchi. The trachea extends from the larynx and branches into the two primary bronchi. It continues down the bronchi and bronchioles, which it completely encircles. Sputum is mucus that is coughed up from the lower airways (the trachea and bronchi). The trachea and the first portions of the main bronchi are outside the lungs. The mammalian lung branching occurs in the epithelium of the developing bronchi and lungs. For nasal mucosa, sinuses, bronchi, and lungs. In contrast to emphysema, asthma affects the bronchi, not the alveoli. MAC usually affects patients with abnormal lungs or bronchi.