Cells, tissues, organs and systems

Multicellular organisms are organised into increasingly complex parts. In order, from least complex to most complex:

  • cells
  • tissues
  • organs
  • organ systems
  • organism

Tissues

Animal cells and plant cells can form tissues, such as muscle tissue in animals. A living tissue is made from a group of cells with a similar structure and function, which all work together to do a particular job. Here are some examples of tissues:

  • muscle
  • the lining of the intestine
  • the lining of the lungs
  • xylem (tubes that carry water in a plant)

Organs

An organ is made from a group of different tissues, which all work together to do a particular job. Here are some examples of organs:

  • heart
  • lung
  • stomach
  • brain
  • leaf
  • root

Organ systems

An organ system is made from a group of different organs, which all work together to do a particular job. Here are some examples of organ systems:

  • circulatory system
  • respiratory system
  • digestive system
  • nervous system
  • reproductive system

Cells are organised into tissues, organs, systems and organisms

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