Lesson: Chapter 6 — Human body processes

6.2. Breathing 1 of 4

Respiration in three stages

Human respiration is a complex process that happens in three stages.

1. External respiration

Air moving between the lungs and the outside — breathing.

2. Gas exchange

Gases passing between the alveoli and the blood.

3. Cellular respiration

Food being oxidised inside the cells to release energy.

External respiration takes oxygen-rich air into the lungs and removes from them the gaseous waste produced by the cells.

Breathing is not respiration

As grade 10 put it, breathing only moves air. Respiration is the chemistry in the cells that releases energy; breathing is just the first of the three stages that make it possible.