Respiration

Respiration is the release of energy from glucose in the muscles.

When the body is at rest this is aerobic respiration. As you exercise you breathe harder and deeper and the heart beats faster to get oxygen to the muscles.

Glucose + oxygen → energy + water + carbon dioxide

When exercising very hard, the heart cannot get enough oxygen to the muscles. Respiration then becomes anaerobic.

Glucose → energy + lactic acid

Inhaled air contains:

• more oxygen used to create energy
• less carbon dioxide than…

Exhaled air which contains:

• more carbon dioxide produced as a waste product of energy production
• less oxygen as it has been used in respiration

Gas exchange takes place by diffusion in the…