# 77 Respiration realeases energy from food
Respiration is the chemical reactions that break down nutrient molecules in living cells to release energy.
In humans, our cells need energy (ATP) for:
All this energy comes from the food we eat. Water soluble molecules are absorbed from the intestine into the blood.
The main energy–providing nutrient: glucose (contains a lot of chemical energy).
There are 2 types of respiration:
- muscle contraction
- making protein molecules: linking together amino acids into long chains
- cell division: to repair damaged tissues and so that we can grow
- active transport
- transmitting nerve impulses
- maintenance of constant body t°
All this energy comes from the food we eat. Water soluble molecules are absorbed from the intestine into the blood.
The main energy–providing nutrient: glucose (contains a lot of chemical energy).
There are 2 types of respiration: