Respiration

Respiration is a chemical process that happens in all living cells. It releases energy from glucose, which is needed for everything from muscle movement to cell repair. Learn about aerobic and anaerobic respiration, how they differ, and why respiration is vital for life.

What Is Respiration?

Respiration is a chemical reaction that takes place in every cell of your body. It releases the energy needed for essential processes like movement, cell division, and keeping warm. It’s not the same as breathing — respiration happens inside cells.

Aerobic Respiration

This type of respiration uses oxygen to release energy from glucose. The word equation is:

Glucose + Oxygen → Carbon dioxide + Water (+ energy)

Aerobic respiration happens constantly in plants, animals, and other organisms to supply energy efficiently.

Anaerobic Respiration

When there isn’t enough oxygen (like during intense exercise), your body switches to anaerobic respiration. In animals, the word equation is:

Glucose → Lactic acid (+ less energy)

Anaerobic respiration releases much less energy than aerobic respiration and leads to a build-up of lactic acid, which can cause muscle fatigue.

Exercise and Respiration

During exercise, your muscles need more energy, so breathing rate, heart rate, and blood flow increase to deliver more oxygen and glucose.
If the demand for energy becomes too high, anaerobic respiration begins, producing lactic acid and leading to an oxygen debt — the extra oxygen needed to break down the lactic acid after exercise.

Metabolism

Metabolism is the term for all the chemical reactions in the body, including respiration. These reactions are controlled by enzymes and involve building new molecules (like proteins) and breaking down substances (like glucose during respiration).

Also see The Lungs & Heart, Homeostasis, Non-Communicable Diseases

Links for learning

BBC Bitesize: Respiration
Study Rocket: Cellular Respiration
The Science Sauce: Respiration
BBC Bitesize: Anaerobic Respiration
By Jus: Aerobic & Anaerobic Respiration