Week 1 - Cells, Tissues, Organs And Systems

• Structural levels of organisation in the human body

  • Chemical Level
  • Cellular Level
  • Tissue Level
  • Organ Level
  • System Level
  • Organismic Level
• Cell


  The basic unit of any living organism. Cells differ in their size, shape, chemical composition, etc.
• Cell structure


  • Determined by function
  • Muscle cells have the ability to move or contract
  • Nerve cells are specialised for conductivity giving them the ability to transmit impulses
• Types of cells


  • Eukaryotic (contain a nucleus, can be single-celled or multicellular)
  • Prokaryotic (do not contain a nucleus, single celled only)
• Mitochondria


  • Site of cellular respiration
  • Originally a prokaryote that entered into a symbiotic relationship with another cell
  • Contains protein that are the site of ATP, which is referred to as energy
• Passive processes


  Occur due to Brownian motion, which is the random movement of all substances due to their charges
• Diffusion


  Movement of substances from where there is more of it (higher density) to where there is less of it (lower density)
• Active transport


  Movement of a substance from a lower concentration to a higher concentration using a carrier and energy
• The trillions of cells found in the human body are made up of over 200 different cell types, that vary in size, shape and function
• Basic tissue types


  • Epithelial
  • Nervous
  • Muscular
  • Connective
• Epithelial tissue


  • Sheets of cells that cover exterior surfaces of the body, lines the internal cavities and passageways
• Nervous tissue


  • Responds to stimulus, contains two categories of cells which include neurons and neuroglia. Examples include spinal cord, brain and nerves
• Muscular tissue


  • Responds to stimulus, There are three types of muscle tissue which include skeletal, visceral (smooth) and cardiac
• Connective tissue


  • Specialises in absorption, secretion and provision of protective barriers. Examples include bones, cartilage and blood
• Examples of organs


  • Heart
  • Brain
  • Skin
  • Liver
  • Pancreas
  • Kidneys
  • Intestines
  • Bladder