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Human Body Study

Lungs

The pair of spongy organs that house gas exchange — the central organs of breathing.

The respiratory tract From the upper airway down through larynx, trachea and bronchial branching into the two lungs, with the diaphragm at the base. A separate inset shows alveoli — the microscopic gas-exchange sacs inside the lungs. Each label links to the article for that part. Alveoli Upper respiratory tract Larynx Trachea Bronchi Lungs Diaphragm The respiratory tract — schematic, not to scale.

Structure

Section titled “Structure”

Two lungs (the right has three lobes, the left two, leaving room for the heart), filled with the branching airway tree and roughly 300 million air sacs (alveoli). Each lung is wrapped in a slippery double membrane, the pleura.

What they do

Section titled “What they do”
  • Hold the surface where oxygen and carbon dioxide are exchanged.
  • Expand and recoil with each breath.

Key idea

Section titled “Key idea”

The lungs themselves cannot move air — they are passive, inflated and deflated by the diaphragm and rib muscles around them.