Exchange Of Gases

The thoracic cavity is anatomically an air tight chamber as it consists of lungs that further consist of air sacs in which the air remains trapped. The contraction of the external intercostal muscles lifts up the ribs and sternum. transport both and . Healthy man can inspire or expire to of air per minute.

and are exchanged in the alveoli by simple diffusion. The factors that affect the diffusion are pressure gradient of the gases, solubility of the gases and the thickness of the membranes involved in diffusion.