human body organization

• Levels of organization of life


  • Biosphere
  • Ecosystem
  • Community
  • Species
  • Population
  • Multicellular organism
  • Organ system
  • Organ
  • Tissue
  • Cell
  • Molecule
  • Atom
• Tissue


  A group of similar cells that perform a specific function
• Epithelial tissue


  • Covers and protects all body surfaces inside and out
  • Bottom layer contains proteins that serve as anchor (basement membrane)
  • Cells can be found as a single layer (simple), or many layers (stratified)
  • Three types of cells (each with function)
• Epithelial tissue cells


  • Squamous cells
  • Cuboidal cells
  • Columnar cells
• Connective tissue


  • Supports the body, connects structures, and separates tissues and organs
  • Can be loose, dense, or specialized
• Connective tissue types


  • Loose (areolar tissue, adipose tissue)
  • Dense (tendons, ligaments)
  • Specialized (bone, cartilage, blood, adipose)
• Nervous tissue


  • Made of cells called neurons
  • Found in brain, spinal cord, and nerves
  • Detects stimuli, integrates information, and controls the actions of the muscles and glands
• Muscle tissue


  • Cells are called muscle fibers
  • Found in muscles
  • Contracts in response to signals from the nervous system
  • Three types: skeletal, cardiac, smooth
• Lines of defense in the immune system


  • External defence (non-specific defences)
  • Innate immune response (non-specific defences)
  • Adaptive immune response (specific defences)
• External defence (non-specific defences)


  • Prevent microbes from entering the body and bacteria trying to invade
  • Includes external surfaces/epithelial tissue, hair/hair follicles, tears, mucous membranes, eyelashes
• Innate immune response (non-specific defences)


  1. Attack microbes once inside the body

  2. Includes white blood cells (phagocytes, natural killer cells)

  3. Inflammatory response (redness, heat, swelling, pain, loss of function)
• Adaptive immune response (specific defences)


  • Attack microbes based on their nature and remembers them for the future
  • Includes recognition, specificity, diversity, memory
• Antigen-antibody relationship


  Antibodies: slow down the progress of a disease (do not kill), proteins molecules produced by B-cells

  Antigens: spikey proteins outside pathogen
• 1. cell response

  2. cells start doing mitosis to create an "army" of b-cells

  Effector cells: mass produce antibodies to fight pathogen (attack)

  Memory cells: remember the antibody and antigen
• Autoimmune diseases occur when the immune system produces antibodies that attack the body's own tissues