Question

How does respiration occur?

Answer 1

Breathing consists of inhalation and exhalation. During inhalation, air enters the lungs. Oxygen from the inhaled air passes into the blood, while carbon dioxide moves from the blood into the lungs. During exhalation, carbon dioxide is expelled from the body. This exchange of gases occurs across the alveolar membrane and is called external respiration.

Red blood cells transport oxygen to every cell. Inside the mitochondria, cellular respiration, or internal respiration, takes place. Oxygen is used to produce energy, and the oxidation of food nutrients releases energy as ATP.