Respiration

See also the section on the Respiratory system here

This is the process that releases energy from food, converting glucose into energy.

There are 2 kinds of respiration:

Aerobic respiration -with oxygen (O₂)

During aerobic activity, your heart and lungs supply the muscles with O₂

Glucose + O₂ > CO₂+ H₂O + energy

You breath out the CO₂ through your lungs, and lose water through sweat, urine or in the air.

As long as your muscles are supplied with enough O₂, you can take part in aerobic exercise, so this is used for long periods of exercise. e.g. Marathon runners

This video shows Science presenter Jon Chase describing aerobic respiration as the release of energy from glucose in the presence of oxygen. The word equation is shown. Mitochondria are stated as the major site of cellular respiration. The reaction is described as slow and controlled. A practical demonstration of the oxidation a jelly baby in molten potassium chlorate(V) is shown to demonstrate how much energy is stored in food.

Anaerobic respiration -without oxygen

Muscles are not supplied with enough O₂ during this

Glucose + no O₂ > lactic acid + energy

Lactic acid builds up if there is a shortage of O₂ (O₂ debt).

This is a mild poison, which makes the muscles feel tired, so is used over short, strenuous activities. e.g. Sprinters