# Human Organ Systems

Source: https://projectgcse.co.uk/biology/human_biology/human_organ_systems

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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