Respiratory System Anatomy
Visual guide to respiratory structures

Notice how the airways branch like a tree. Air travels from the single trachea to millions of alveoli.

See the branching network? The bronchi divide into smaller and smaller tubes. The pleural membranes wrap around each lung.

These tiny sacs are wrapped in blood vessels. The walls are so thin that oxygen and CO₂ can pass through easily.

Three layers separate air from blood: (1) Alveolar wall (one cell thick), (2) Basement membrane (very thin), (3) Capillary wall (one cell thick). Total thickness: Less than 1 millimeter!

During breathing: Epiglottis is open, air flows to trachea. During swallowing: Epiglottis closes, food goes to esophagus.








