VMBO Year 3 · Organs and cells · Section 1.2
The organisation of an organism
From cell to organism
Living things are made of cells. In multicellular organisms, these building blocks are organised at different levels. Cells form tissues; tissues form organs; organs work together in organ systems. Together, the organ systems make up an organism. These steps are called levels of organisation.
Cell → tissue → organ → organ system → organism
How does this work in the body?
An organ system is a group of organs working together on a task, such as digesting food or circulating blood. Each organ has one or more functions. The stomach, for example, churns food and mixes it with gastric juice.
Organs consist of different tissues. A tissue is a group of cells with a similar structure and a shared function. Muscle tissue contains elongated muscle cells that can contract. Many tissues also contain extracellular matrix, material between the cells. This can be soft or fluid, or hard as in bone. Its properties help make a tissue flexible or strong, depending on its function.
Everything works together
When you kick a ball, your bones, muscles, nerves and brain work together. All the levels of organisation are involved, allowing your body to coordinate a quick movement.
Glossary
- Cell
- The smallest living building block of an organism.
- Organ
- A part of the body with one or more functions.
- Organ system
- A group of organs working together, such as the digestive or respiratory system.
- Level of organisation
- A level at which biologists study life. Smaller levels form the building blocks of larger ones; organs, for example, form organ systems.
- Extracellular matrix
- Material outside and between cells which, together with the cells, forms a tissue. Its properties affect the tissue's characteristics.
- Tissue
- A group of cells with a similar structure and a shared function.