Presentation on theme: "AP Biology Immune System phagocytic leukocyte Fighting the Enemy Within! Big Questions: 1.What is the purpose of a immune system? 2.How does the immune."— Presentation transcript:
AP Biology Immune System phagocytic leukocyte Fighting the Enemy Within! Big Questions: 1.What is the purpose of a immune system? 2.How does the immune system function? 3.Why do animals have a more developed immune system?
AP Biology Immune Systems Highly developed in mammals Two types of immunity: 1. Innate immunity (nonspecific) 2. Adaptive immunity (specific) What about other organisms? Lymphatic System: Production & transport of leukocytes (WBC) Traps foreign invaders
AP Biology 2nd line: Non-specific patrolling cells attack pathogens, but don’t “remember” for next time leukocytes phagocytic white blood cells macrophages, neutrophils, natural killer cells, dendritic cells Antimicrobial proteins Complement system Interferons inflammatory response increase in body temp. increase capillary permeability attract macrophages/neutrophils yeast macrophage bacteria
AP Biology Inflammatory response Histamine and cytokines increase blood flow to damaged site, making it look red and puffy = INFLAMMED!
AP Biology Fever When a local response is not enough system-wide response to infection activated macrophages release interleukin-1 triggers hypothalamus in brain to readjust body thermostat to raise body temperature higher temperature helps defense inhibits bacterial growth stimulates phagocytosis speeds up repair of tissues causes liver & spleen to store iron, reducing blood iron levels bacteria need large amounts of iron to grow
AP Biology Specific defense with memory lymphocytes B cells - humoral response T cells – cell mediated response They respond to… Antigens! 3rd line: Adaptive (active) Immunity B cell
AP Biology B cells Involved in HUMORAL RESPONSE Attacks foreign antigens in blood or lymph Produce specific antibodies against specific antigens Types of B cells plasma cells immediate production of antibodies rapid response, short term release memory cells continued circulation in body long term immunity
AP Biology “self”“foreign” How are invaders recognized? Antigens - cellular name tag proteins “self” antigens no response from WBCs Major Histocompatibility Complex – MHC Protein used by all cells for recognition “foreign” antigens response from WBCs pathogens: viruses, bacteria, protozoa, parasitic worms, fungi, toxins non-pathogens: cancer cells, transplanted tissue, pollen Mature lymphocytes are tested to make sure they can distinguish self vs. non-self
T cells Involved in CELL MEDIATED RESPONSE 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 helper T cells alerts rest of immune system killer (cytotoxic) T cells attack infected body cells memory T cells long term immunity T cell attacking cancer cell
AP Biology How do T cells know a cell is infected? Infected cells digest some pathogens MHC proteins carry pieces to cell surface foreign antigens now on cell membrane called Antigen Presenting Cell (APC) Many different WBC’s can also serve as APC tested by Helper T cells MHC proteins displaying foreign antigens infected cell T cell with antigen receptors T H cell WANTED
AP Biology Cell-Mediated Response Cytotoxic T cells destroy infected body cells or cancer cells secretes perforin protein causing apoptosis or lysis of infected cell Creates memory killer-T’s for further exposures
AP Biology What is Immunity? 2 Types: ACTIVE and PASSIVE
AP Biology Active Immunity Get exposed to pathogen! Naturally – get sick Artificially – get a vaccination Both methods cause memory cells to be made for future exposures. Rapid response to second exposure. You don’t even know you were exposed!
Naturally obtaining antibodies from mother antibodies pass from mother to baby across placenta or in mother’s milk critical role of breastfeeding in infant health Artificially injection of antibodies Ex: anti-venom serum short-term immunity Passive immunity (antibodies not immune cells)
AP Biology Human Immunodeficiency Virus virus infects helper T cells AIDS: Acquired ImmunoDeficiency Syndrome infections and death by opportunistic diseases pneumonia, cancers HIV & AIDS HIV infected T cell
Immune system malfunctions Auto-immune diseases immune system attacks own molecules & cells rheumatoid arthritis Diabetes multiple sclerosis Allergies makes wrong antibody for foreign antigen allergens = proteins on pollen, dust mites, in animal saliva 1 st exposure you are not allergic. Allergy is confirmed after subsequent exposures