Physiology 2130 Lecture 10: Module 10
8 Dec 2016
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Document Summary
The lungs are located in the thoracic cavity and are surrounded by the rib cage and the diaphragm. The airways consist of the nasal cavity and the mouth, which join together at the pharynx. The pharynx leads into the larynx or voice box, which then becomes the trachea. The trachea divides into two main bronchi (left and right), which continually divide into smaller and smaller bronchioles. These bronchioles continually divide and eventually end in the alveoli, which are the site of gas exchange in the lung. The pulmonary artery, which delivers deoxygenated blood to the lungs, branches extensively to form a dense network of capillaries and blood ow characteristics maximize gas exchange. These characteristics include thin endothelial walls, large total cross-sectional area, and a very low blood velocity. Hence, in the capillaries oxygen diffuses into the blood while co2 diffuses out. From the capillaries the oxygen-rich blood ows back to the left side of the heart through the pulmonary vein.
