From cell to organ system

The idea

A group of similar cells performing similar functions forms a tissue, different tissues form an organ, and several organs work together as an organ system; the cell remains the fundamental unit throughout.

A body of teamwork

Your body is made of millions of cells. They are not scattered like sand. They are organised.

How do you think cells are organised?

• In groups, which then form bigger parts
• Each cell works completely alone
• Randomly, with no order

Zoom out

Choose a level. Watch how cells build up into a whole system.

Cells → tissues → organs → organ systems

A group of similar cells doing similar functions forms a tissue. Different tissues form an organ. Several organs working together form an organ system. Through all levels the cell remains the fundamental unit.

Nasal pores, nasal cavity, trachea and lungs together form the respiratory system.

• Level | Made of | Example
• Cell | one living unit | a lining cell
• Tissue | similar cells | lining tissue
• Organ | different tissues | trachea, lungs
• Organ system | several organs | respiratory system

Notes

Similar cells form a tissue; different tissues form an organ; several organs form an organ system. The cell is the fundamental unit throughout.

Check yourself

A group of similar cells doing a similar job is called…

Nasal pores, nasal cavity, trachea and lungs together form the…

Which is the fundamental unit at every level of organisation?

• a tissue — correct. Yes.
• an organ. An organ is made of different tissues.
• an organ system. That is several organs.
• an organism. That is the whole living thing.
• respiratory system — correct. Yes. An organ system.
• respiratory tissue. A tissue is a group of similar cells.
• respiratory cell. A cell is one unit.
• the cell — correct. Yes. Tissues, organs and systems are all made of cells.
• the tissue. Tissues are made of cells.
• the organ. Organs are made of tissues, which are made of cells.