Function of the major organs
Home learning focus
An organ is a group of different tissues that work together to do a particular job. Organs are grouped together into organ systems. Learn about the organs in the human body.
This lesson includes:
- two videos to help you understand organs
- three practise activities to help reinforce learning
Animals and plants are made of cells. Tissues are made from cells of a similar type. Organs are made from tissues, and systems are made from several organs working together.
An organ is a group of different tissues that work together to do a particular job.
Organs are grouped together into organ systems.
Examples of organ systems include the circulatory system and the digestive system.
In this film learn how cells are organised into tissues, organs, systems and organisms:
Living organisms have certain life processes in common.
There are seven things that they need to do to count as being alive.
The phrase MRS GREN is one way to remember them:
- Movement - all living things move, even plants
- Respiration - getting energy from food
- Sensitivity - detecting changes in the surroundings
- Growth - all living things grow
- Reproduction - making more living things of the same type
- Excretion - getting rid of waste
- Nutrition - taking in and using food
In this film we hear from a specialist nurse talking about her work in organ donation:
Layers of organisation
The human body is made up of many cells, so it is an example of a multicellular organism.
A multicellular organism has five layers of organisation, called a hierarchy.
Here they are in order of complexity:
- Organelles - tiny structures which carry out various functions within a cell.
- Cells - the basic unit of all living organisms.
- Tissues - groups of similar cells that work together to perform a specific function. For example, brain tissue, muscle tissue and heart tissue.
- Organs - different tissues working together to carry out a particular function.
- Organ system - a group of organs that work together to do a job.
In an organ, different tissues work together to carry out a particular function.
These are the main organs, as well as their primary function:
- The brain controls thoughts, memory and other organs.
- The heart pumps blood around the body.
- The lungs separate oxygen from the air and remove carbon dioxide from the blood.
- The stomach helps to digest food.
- The intestines absorb nutrients from food.
- The liver removes poisons from the blood.
- The kidneys filter blood and produce urine.
- The bladder stores urine.
- The skin protects and contains the other organs.
Organs are organised into organ systems. An organ system is a group of organs that work together to do a job.
Key human organ systems:
- The circulatory system includes the heart, veins and arteries. Its function is to transport substances in the blood, around the body.
- The respiratory system includes the nose and the lungs. It takes in oxygen and removes carbon dioxide.
- The digestive system includes the stomach and intestines. It breaks down food and absorbs nutrients.
- The reproductive system includes the uterus and vagina in women, and the penis and testes in men. Its function is to create offspring.
- The musculoskeletal system includes bones and muscles. It supports the body and allows movement.
- The immune system includes bone marrow. It protects the body from infection.
There are lots of fun ways to practise what you know about organs.
Drag and drop the labels to the correct organ:
Test your knowledge of organs in this quiz:
There's more to learn
Have a look at these other resources around the BBC and the web.