Fighting the Enemy Within! Immune / Lymphatic System phagocytic leukocyte Fighting the Enemy Within! Immune / Lymphatic System lymphocytes attacking cancer cell lymph system 2007-2008

Avenues of attack Points of entry Routes of attack _________ respiratory system ______________ break in skin Routes of attack _____________ lymph system

What’s in your lunchbox? Why an immune system? Attack from outside animals must defend themselves against invaders (pathogens) ______________ HIV, flu, cold, measles, chicken pox bacteria pneumonia, meningitis, tuberculosis Lyme disease yeast (“Athlete’s foot”…) protists amoeba, malaria Attack from inside _______________________ Mmmmm, What’s in your lunchbox?

Lymph system Production & transport of leukocytes Traps foreign invaders Lymph system lymph vessels (intertwined amongst blood vessels) lymph node

Bacteria & insects inherit resistance. Vertebrates acquire immunity. Lines of defense 1st line: ___________________ broad, external defense “walls & moats” skin & mucous membranes 2nd line: ________________ broad, internal defense “patrolling soldiers” leukocytes = phagocytic WBC 3rd line: _________________ specific, acquired immunity “elite trained units” lymphocytes & antibodies B cells & T cells Bacteria & insects inherit resistance. Vertebrates acquire immunity.

1st line: Non-specific External defense Barrier skin __________ mucous membranes, cilia, hair, earwax Elimination coughing, sneezing, urination, diarrhea ______________ stomach acid, sweat, saliva, urine Lining of trachea: ciliated cells & mucus secreting cells

2nd line: Non-specific patrolling cells bacteria Patrolling cells & proteins attack pathogens, but don’t “remember” for next time leukocytes phagocytic white blood cells macrophages, neutrophils, natural killer cells complement system proteins that destroy cells inflammatory response increase in body temp. increase capillary permeability attract macrophages macrophage yeast

Leukocytes: Phagocytic WBCs Attracted by chemical signals released by damaged cells ingest pathogens digest in lysosomes _______________ most abundant WBC (~70%) ~ 3 day lifespan “big eater”, long-lived ______________ destroy virus-infected cells & cancer cells

Destroying cells gone bad! Natural Killer Cells perforate cells ________________________ insert into membrane of target cell forms pore allowing fluid to flow in & out of cell cell ruptures (lysis) apoptosis vesicle natural killer cell perforin cell membrane perforin punctures cell membrane cell membrane virus-infected cell

Inflammatory response Damage to tissue triggers local non-specific ___________________________ release chemical signals capillaries dilate, become more permeable (leaky) delivers macrophages, RBCs, platelets, clotting factors ______________________ decrease bacterial growth stimulates phagocytosis speeds up repair of tissues

Fever When a local response is not enough ___________________________ higher temperature helps defense _____________________ stimulates phagocytosis ________________________ causes liver & spleen to store iron, reducing blood iron levels bacteria need large amounts of iron to grow Certain bacterial infections can induce an overwhelming systemic inflammatory response leading to a condition known as septic shock. Characterized by high fever and low blood pressure, septic shock is the most common cause of death in U.S. critical care units. Clearly, while local inflammation is an essential step toward healing, widespread inflammation can be devastating.

3rd line: Acquired (active) Immunity Specific defense with memory _________________ B cells T cells antibodies Responds to… _____________ cellular name tags specific pathogens specific toxins abnormal body cells (cancer) B cell

How are invaders recognized? Antigens cellular name tag proteins ________________ no response from WBCs _________________ response from WBCs pathogens: viruses, bacteria, protozoa, parasitic worms, fungi, toxins non-pathogens: cancer cells, transplanted tissue, pollen “self” “foreign”

Lymphocytes B cells T cells “Maturation” humoral response system bone marrow Lymphocytes B cells humoral response system _______________ T cells cellular mediated response system _________________ “Maturation” learn to distinguish “self” from “non-self” antigens if react to “self” antigens, cells are destroyed during maturation Tens of millions of different T cells are produced, each one specializing in the recognition of oen particar antigen.

B cells Attack, learn & remember pathogens circulating in blood & lymph Produce specific ___________ against specific __________ Types of B cells __________________ immediate production of antibodies rapid response, short term release memory cells continued circulation in body long term immunity

Antibodies Proteins that bind to a specific antigen Y Y Y Y Y Y Y Y Y binding region matches molecular shape of antigens each antibody is unique & specific tagging “handcuffs” “this is foreign…gotcha!” Y Y Y antigen- binding site on antibody antigen Y Y Y Y variable binding region Y Y each B cell has ~50,000 antibodies

What do antibodies do to invaders? neutralize capture precipitate apoptosis macrophage eating tagged invaders invading pathogens tagged with antibodies Y

invader (foreign antigen) 10 to 17 days for full response B cell immune response B cells + antibodies Y invader (foreign antigen) tested by B cells (in blood & lymph) memory cells “reserves” Y Y recognition Y captured invaders macrophage Y clones 1000s of clone cells plasma cells release antibodies Y Y

Vaccinations Immune system exposed to harmless version of pathogen ________________________________________________________________ “active immunity” rapid response on future exposure creates immunity without getting disease! _______________

Passive immunity Obtaining antibodies from another individual _________________ antibodies pass from mother to baby across placenta or in mother’s milk critical role of breastfeeding in infant health mother is creating antibodies against pathogens baby is being exposed to _______________ injection of antibodies short-term immunity

What if the attacker gets past the B cells in the blood & actually infects (hides in) some of your cells? You need trained assassins to recognize & kill off these infected cells! Attack of the Killer T cells! T But how do T cells know someone is hiding in there? 2007-2008

T cells Attack, learn & remember pathogens hiding in infected cells recognize antigen fragments also defend against “non-self” body cells cancer & transplant cells Types of T cells ___________ alerts rest of immune system ___________________ attack infected body cells _______________ long term immunity T cell attacking cancer cell

Attack of the Killer T cells Destroys infected body cells binds to target cell ______________________ punctures cell membrane of infected cell apoptosis vesicle Killer T cell Killer T cell binds to infected cell cell membrane perforin punctures cell membrane cell membrane infected cell destroyed target cell

Immune system & Blood type antigen on RBC antibodies in blood donationstatus A type A antigens on surface of RBC anti-B antibodies __ B type B antigens on surface of RBC anti-A antibodies AB both type A & type B antigens on surface of RBC no antibodies universal recipient O no antigens on surface of RBC anti-A & anti-B antibodies universal donor Matching compatible blood groups is critical for blood transfusions A person produces antibodies against foreign blood antigens