Defense against immune system

• What causes infectious diseases?

  Pathogens
• What types of organisms can be pathogens?

  Bacteria, fungi, protozoa, and viruses
• What are the primary defense mechanisms of the body?

  Skin and mucus membranes
• What is the outer layer of skin made of?

  Dead cells
• How does skin protect against pathogens?

  It forms an impenetrable barrier
• What are mucus membranes?

  Membranes that produce sticky mucus
• What is the function of mucus in the body?

  It traps pathogens
• What happens when the skin is cut?

  It creates an opportunity for pathogens
• What is the clotting cascade?

  A sequence of events to form a blood clot
• What are platelets?

  Tiny cell fragments in blood
• What do platelets release at a cut site?

  Clotting factors
• What does thrombin do?

  Converts fibrinogen into fibrin
• What is fibrinogen?

  A soluble blood protein
• What is the role of fibrin in blood clotting?

  It forms a mesh to trap blood cells
• What distinguishes primary defense from immunity?

  Primary defense is physical; immunity is cellular
• What are the two types of immunity?

  Innate and adaptive immunity
• What are phagocytes?

  Cells that engulf pathogens
• How does the innate immune system function?

  It attacks anything that doesn't belong
• What are lymphocytes responsible for?

  Building immunity and memory
• What are the two types of lymphocytes?

  T cells and B cells
• What do T cells do?

  Identify B cells that produce antibodies
• What happens during clonal selection of B cells?

  B cells clone themselves via mitosis
• What do plasma cells produce?

  Antibodies
• What are memory cells?

  Cells that remain for future infections
• How do phagocytes identify pathogens?

  By reading antigens on the cell surface
• What is antigen presentation?

  Displaying a destroyed pathogen on the surface
• What activates T cells?

  Antigen presentation by phagocytes
• What is the role of B cells in the immune response?

  Produce specific antibodies against pathogens
• What is the significance of having many types of lymphocytes?

  To produce antibodies for various antigens
• What happens if type A blood is injected into a type B individual?

  Anti-A antibodies will bind to type A cells
• Why is matching blood types important for transfusions?

  To prevent immune responses against foreign antigens
• What is the first step in the adaptive immune response?

  Engulfing the pathogen by phagocytes
• What is the role of helper T cells?

  To locate specific B cells for antibody production
• What happens after a B cell is activated?

  It clones itself and differentiates
• What do plasma cells do after differentiation?

  Secrete large amounts of antibodies
• What is the function of rough endoplasmic reticulum in plasma cells?

  To produce antibodies
• What is the overall goal of the immune response?

  To produce antibodies against pathogens