bio chap 6 n 7 ( immunity)

• Rapid reproduction of the pathogen being faster than body
• Disease


  Any change that impairs the function of someone
• Non-cellular agents


  Not made of cells and can’t reproduce/function without a host
• Non-cellular agents


  • COVID-19
• Cellular agents


  Can reproduce and function by themselves
• Cellular agents


  • Gastro, fungi, protists
• Infection


  When pathogenic bacteria, viruses or other microbes gain entry to the human body and begin to multiply
• Pathogen gains entry into the body through the nose, throat, mouth, urethra, and genital opening
• Asymptomatic carriers


  Carriers of the pathogen but don’t show any symptoms/signs
• Asymptomatic carriers can spread the pathogen to many people without knowing
• How infectious diseases are spread

  • Direct (kissing, sexual contact)
  • Indirect (droplets, sneezes, ingestion)
  • Vectors (carry pathogen from a host bird to people)
• Shape of bacteria


  • Round shaped - coccus
  • Rod shaped - Bacillus
  • Spiral shaped - spirochaete
• Gram staining


  • Gram positive (A), wall takes up stain, susceptible to penicillin
  • Gram negative (B), doesn’t stain, resistant to penicillin
• Flagella in bacteria


  Allow bacteria to move, thin thread appendage
• 1st line of defense


  • Intact skin
  • Mucous membrane
  • Saliva
  • Tears
  • Sweat
  • Natural flora
  • stomach acid
• Pathogen


  An organism or agent that causes a disease in another
• Exotoxins


  Toxins that are released into surroundings of bacteria
• Endotoxins


  Toxins in the cell wall and only released after the cell breaks open
• Virus


  A virus is a cell that injects nucleic acid into a host and takes over cell machinery
• Bacteriophages


  Viruses that infect bacteria and they enter and lyse bacteria
• How infected prions convert other prions

  1. Come in contact

  2. Change amino acid to unfold and refold into an abnormal shape
• Antigen (immunogen)


  A protein that triggers an immune response from B or T cells
• The immune system ignores cells with self antigens because of the self receptors on WBC that recognize the self antigens
• Viruses


  Obligate intracellular parasites that must infect a host cell before they reproduce
• The rate of mutation on RNA viruses is faster because RNA nucleotides tend to be more unstable
• Purpose of the 2nd line of defense

  To ID, engulf and destroy pathogens
• How viruses cause damage to host

  Virus injects nucleic acid into host cells where it damages the cell machinery
• How viruses spread


  1. Rupture the cell (lysis)

  2. Cell exploding releases viral particles to other host cells
• How prions infect other proteins in neurons

  Change the amino acid shape to unfold and refold it abnormally
• Self antigens


  Cells that our body makes
• How WBC recognize non-self antigens

  They have non-self receptors on WBC
• Physical barriers for 1st line of defense

  • Intact skin
  • Hair
  • Shedding dead skin
  • Sebum production
  • Tears
  • Sweat
• Chemical barriers for 1st line

  • Mucous
  • Acid secretion from vagina
  • Natural flora
• Natural flora


  Micro bacteria that acts as competition to pathogens, inhibiting growth of pathogenic bacteria
• Physical barriers for plants

  • Bark (dead layer)
  • Waxy cuticles
  • Cell wall
  • Verticals
  • Spikes
  • Hairs
• Chemical barriers for plants

  • Secretion of a toxin or odour
  • Production of enzymes
  • Defensins
  • Saponins
• Second line of defense

  • White blood cells
  • Soluble proteins (inflammation)
• Main function of phagocytic cells

  To ID, engulf and digest
• Granulocytes


  WBC that have digesting enzymes inside, e.g. lysosome
• Complement proteins


  Helper proteins that spray and coat the infected cells, disarming them from spreading