Cell Organisation

• Differentiation

  the process by which cells become specialised for a particular job
• Differentiation occurs during the development of a multicellular organism
• Specialised cells form tissues, which form organs, which form organ systems
• Large multicellular organisms have different systems inside them for exchanging and transporting materials
• Tissue

  a group of similar cells that work together to carry out a particular function
• A tissue can include more than one type of cell
• Examples of tissues in mammals:

  • muscular tissue - contracts to move whatever it's attached to
  • glandular tissue - makes and secretes chemicals like enzymes and hormones
  • epithelial tissue - covers parts of the body like the inside of the gut
• Organ

  a group of different tissues that work together to perform a certain function
• Example of an organ: stomach

  • muscular tissue - moves stomach wall to churn up the food
  • glandular tissue - makes digestive juices to digest food
  • epithelial tissue - covers the outside and inside of the stomach
• Organ system

  a group of organs working together to perform a particular function
• The digestive system in humans breaks down and absorbs food
• The digestive system is made up of:

  • glands - produce digestive juices
  • stomach and small intestine - digest food
  • liver - produces bile
  • small intestine - absorbs soluble food molecules
  • large intestine - absorbs water from undigested food, leaving faeces
• Organ systems work together to make entire organisms