Gas Exchange and Ventilation

Gas exchange is the process of taking in oxygen for respiration and removing the waste carbon dioxide produced by cells. In humans this occurs in the lungs, where air is brought close to blood across an extremely thin, moist surface.

The Ventilation System

Air enters through the nose and mouth, passes down the trachea, and divides into two bronchi, one for each lung. The bronchi branch repeatedly into narrower bronchioles, which end in clusters of tiny air sacs called alveoli. The trachea and bronchi are supported by rings of cartilage that keep the airways open, and their linings contain ciliated cells and goblet cells that produce mucus to trap dust and microbes, sweeping them away from the lungs.

Alveoli and Gas Exchange

The alveoli are the site of gas exchange and are superbly adapted