Levels of organisation
In order of increasing complexity, multicellular organisms are made of:
cells → tissues → organs → organ systems
| Structure | Description |
| Organelle | A specialised unit within a cell which performs a specific function |
| Cell | The basic building block of all living organisms |
| Tissue | A group of cells working together to perform a shared function, and often with similar structure |
| Organ | A structure made up of groups of different tissues, working together to perform specific functions |
| Organ system | A group of organs with related functions, working together to perform certain functions within the body |
| Structure | Organelle |
|---|---|
| Description | A specialised unit within a cell which performs a specific function |
| Structure | Cell |
|---|---|
| Description | The basic building block of all living organisms |
| Structure | Tissue |
|---|---|
| Description | A group of cells working together to perform a shared function, and often with similar structure |
| Structure | Organ |
|---|---|
| Description | A structure made up of groups of different tissues, working together to perform specific functions |
| Structure | Organ system |
|---|---|
| Description | A group of organs with related functions, working together to perform certain functions within the body |
An example of the levels of organisation using the circulatory system