6.3

• Opportunistic microorganisms


  Can invade the body but also live outside it
• Specialized microorganisms


  Can only survive inside a human body
• Pathogenic/Pathogens

  Microbes that cause disease
• Sebum


  Maintains skin moisture and slightly lowers skin pH
• Mucus

  A physical barrier; pathogens and harmful particles are trapped in it and either swallowed or expelled; has antiseptic properties
• Antiseptic properties

  In mucus; due to the presence of the anti-bacterial enzyme lysozyme.
• Clotting

  Process that stops bleeding
• Cascade of reactions


  Happens in the clotting of blood; each reactions produces a catalyst for the next reaction
• Platelets


  Cellular fragments that circulate in the blood
• Thrombin


  Enzyme that converts fibrinogen into fibrin
• Fibrinogen


  Soluble protein that is converted to fibrin by thrombin
• Fibrin


  Insoluble protein that helps in the formation of scabs
• Phagocytes

  Engulfs pathogens through endocytosis and digests pathogens with enzymes from lysosomes
• Antigen


  Any chemical that stimulates an immune response
• Immune response


  The production of antibodies in response to a specific pathogen
• Antibodies

  Bind to antigens on a pathogen
• Hyper-variable region (antibody)


  Binds to a specific antigen
• Another region (antibody)

  Makes pathogens more recognisable to phagocytes so they can be more readily engulfed; prevents viruses from latching onto host cells
• Plasma cells


  Large clones of lymphocytes that can produce antibodies
• Lymphocytes


  Produces antibodies
• Memory cells


  Lymphocytes produced in a previous infection that remain inactive until the same pathogen infects the body again; they then become active and divide to rapidly produce plasma cells
• Immunity

  Involves either having antibodies against a pathogen, or memory cells that allow the rapid production of an antibody
• Antibiotic


  Chemical that inhibits the growth of microorganisms
• Virus


  Non-living infectious agent
• Antiviral


  Control viruses without harming the host cell
• Thrombus


  Blood clot
• Coronary thrombosis


  Formation of blood clots in the coronary arteries
• Fibrillation


  Quivering movements of the wall of the heart that causes ineffective pumping of blood
• Atherosclerosis


  Causes occlusion in the coronary arteries
• HIV (human immunodeficiency virus)


  Retrovirus that has genes made of RNA and uses reverse transcriptase to make DNA copies of its genes once it has entered a host cell
• Kaposi's sarcoma


  Marker disease for the latter stages of an HIV infection
• Syndrome


  Several diseases or conditions existing together
• AIDS (acquired immune deficiency syndrome)


  Spread by the HIV virus