Human Organ Systems

Humans have nine major organ systems which make the seven life processes:

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

9) The Muscle System

• Muscles are attached to bones
• Muscles cause movement when they contract and relax
• Muscles are a bit like fading hippies - you usually find them in pairs around a joint