VMBO Year 2 · HAVO/VWO Years 2–3 · Cellular respiration and breathing · Section 1.2

Cellular respiration

Energy

Cells break down glucose to release energy. This energy is needed for activities such as movement and maintaining human body temperature, normally around 37 °C.

This process is called cellular respiration. It does not involve a flame, although it uses a fuel, such as glucose.

Living cells need a continuing supply of usable energy. Respiration occurs day and night, including in plants. Some organisms and cells can also release energy through processes that do not require oxygen.

Oxygen and carbon dioxide

In aerobic respiration, glucose reacts with oxygen. Like a burning candle, this process requires a fuel and oxygen, although cellular reactions are controlled and do not produce a flame.

The products include water and carbon dioxide, and energy is released:

Glucose + oxygen → water + carbon dioxide + energy

The energy supports movement and other cellular activities. Some is released as heat, which can pass into the surroundings.

During physical activity, working muscles need more energy, so the rate of respiration increases. The heart and lungs work harder to supply glucose and oxygen and remove carbon dioxide more quickly.