1) The Digestive System
Digestion breaks down food into simpler substances so it can be used and absorbed into the body
It takes place in the alimentary canal, (food tube), mainly in the stomach and small intestine
Digested food is absorbed into the blood system

2) The Respiratory System
This is for taking in oxygen and removing waste carbon dioxide
Air enters the lungs by movement of the rib muscles and diaphragm
Oxygen is absorbed into the blood system

3) The Excretory System
This removes toxic and other waste materials from the body.
Waste material is filtered out of the blood by the kidneys and made into urine
This is stored in the bladder and released via the urethra

4) The Circulatory System
The heart pumps blood around the body
It supplies cells with oxygen and food, then carries away the wastes like carbon dioxide

5) The Reproductive System
This is for producing offspring
Eggs are produced by the ovaries in a female
Sperm are produced by the testes of a male and they then endeavour to fertilise the eggs

6) The Nervous System
The five sense organs are: eyes, ears, nose, tongues, skin
They all contain nerves, which send messages to the brain about what's happening
The brain produces a response, which it sends via other nerves to the muscles

7) The Endocrine System
This system produces and discharges chemicals called hormones
A number of glands around the body (endocrine system) produce these hormones
Hormones control activities such as growth or sexual characteristics and also bodily functions like menstruation

8) The Skeletal System
There are 206 bones in the human body and their main job is support
Some bones (e.g. the skull) provide a tough barrier to protect delicate organs like the brain
Muscles are attached to the bones which contract and relax allowing movement