---
title: "Cells to organ systems"
description: "Describe organisation in humans and other complex multicellular organisms: cells, tissues, organs, organ systems and the whole organism."
canonical: https://lightmysky.com/learn/science/cells-to-organ-systems-mt_7hB8s5eOP1
source: https://lightmysky.com/learn/science/cells-to-organ-systems-mt_7hB8s5eOP1.md
retrieved: 2026-10-19
---

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# Cells to organ systems

Describe organisation in humans and other complex multicellular organisms: cells, tissues, organs, organ systems and the whole organism.

Subject: Science · Area: Organisms & Life Processes · Ages 11 to 12
Page: https://lightmysky.com/learn/science/cells-to-organ-systems-mt_7hB8s5eOP1

## Ready when they can

- Places cells, tissues, organs, organ systems and the organism in the correct order of organisation
- Gives a specific example of each level, such as cardiac muscle cell, muscle tissue, heart, circulatory system and human
- Explains why specialised cells are needed in a multicellular organism

## Lesson: From cells to organ systems

Some organisms consist of one cell. Humans are multicellular: they have many cells. A cell is the smallest living unit. Cells working together form tissues, such as muscle cells forming muscle tissue. Two or more tissue types work together in an organ. Several organs work together in an organ system. The organism is the whole living thing. This five-level plan describes humans and many other complex organisms.

*(drawing: From smallest to biggest: cell, tissue, organ, organ system, organism.)*

**Example.** Cardiac muscle cells form muscle tissue in your heart. This tissue contracts to help pump blood. Other tissue types also help the heart work. The heart and blood vessels are parts of the circulatory system. Skin is another organ, with several tissue types. The brain is an organ in the nervous system, which also includes nerves. Your organ systems work together in you, the organism.

Specialised cells have structures suited to their jobs. Muscle cells contract, nerve cells carry signals, and red blood cells carry oxygen. Different tasks need cells and tissues working together. A tissue can contain more than one cell type: nervous tissue includes nerve cells and support cells.

**Recap.** Cells group into tissues, tissues into organs, organs into organ systems, and organ systems into you.

## Practice

8 questions on this page, each with its working shown.

## Needs first

- [Plant cells vs animal cells](https://lightmysky.com/learn/science/plant-cells-vs-animal-cells-mt_fhqBH9scsU)

## Opens up

- [Digestion & Enzymes](https://lightmysky.com/learn/science/digestion-and-enzymes-mt_0NlbulkB5P)
- [Pathogens & the Immune System](https://lightmysky.com/learn/science/pathogens-and-the-immune-system-mt_1VIE8FlZvL)
- [The Human Skeleton](https://lightmysky.com/learn/science/the-human-skeleton-mt_Qkl46lyris)
- [Gas Exchange & Breathing](https://lightmysky.com/learn/science/gas-exchange-and-breathing-mt_V9SQS9gLFw)