Question

Short / long answer type questions.
Describe the mechanism of pulmonary gaseous exchange.

Answer 1

• Pulmonary gaseous exchange occurs in the alveoli by simple diffusion. The blood flowing past the alveoli is rich in carbon dioxide and very poor in oxygen. The gas molecules naturally flow in the direction of lower concentration through the thin gas exchange membrane.
  
• The alveoli are small, round protrusions in the lungs. The interior of the alveoli is maximized to provide a large surface area for gas exchange. Capillaries cover the outside walls of the alveoli. These capillaries contain deoxygenated blood that is high in carbon dioxide waste.
  
• The carbon dioxide moves through the thin capillary wall into the alveoli where it mixes with air and is exhaled. At the same time, oxygen in the inhaled air passes into the capillaries, which carry it to nourish other parts of the body.