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6.3 Defence Against Infectious Disease 6.3.4 Outline how phagocytic leucocytes ingest pathogens in the blood and in body tissues. • 1 type of WBCs—macrophages • Lg, change shape to engulf invaders (phagocytosis) & squeeze in/out of capillaries • Recognizes self/non-self • Proteins on cell surface • Self left alone • Non-self phagocytosis, lysosomes of macrophage digest it • “NON-SPECIFIC” DEFENSE b/c invader’s identity’s not known, just that it’s non-self 6.3.5 Distinguish between antigens and antibodies. • ABs-specific proteins we produce, in response to a specific pathogen • Flu AB, measles AB, etc. • Y-shaped, Ag-binding sites at each tip • AB attaches to Ag’s sfc • Cellular invaders (bacteria) • Foreign Proteins @ outer sfc = ANTIGENS (Ags) • Usually have several diff Ag on sfc, so make several diff Abs against it • Viral invaders too 6.3.6 Explain antibody production. • • 1. 2. 3. 4. 5. 6. 7. B Cells (type of WBC) We all have lots diff B cells, each makes a diff AB Specific AG identified (cold virus) Specific B lymphocyte id’d that can produce AB to bind to AG (to proteins on virus coat) B cell & many identical B cells clone selves (mitosis) LOTS in a short period of time “army” of B cells produce ABs ABs released to bloodstream, find AG ABs help eliminate the pathogen (various ways) Some of cloned B cells remain in bloodstream, give immunity from 2nd infection by same pathogen: MEMORY CELLS 6.3.7 Outline the effects of HIV on imm sys. • Viruses work by finding a cell type in body that matches its proteins (complementary)—why only some body cells affected by flu virus (nasal cells nasal symptoms) • HIV (virus) AIDS (symptoms) • Infects Helper T cells • Latency period (infected cells remain alive) of several years before AIDS • Helper T cells communicate which cells need to clone & produce AB • They die no more communication, AB not produced • Can no longer fight off pathogens (even mild ones), often die of 2-ary infections 6.3.8 Discuss the cause, transmission and social implications of AIDS. • Cause: HIV (6.3.7) • difficult to make vaccine b/c it hides latent for yrs & b/c it mutates quickly • Medication-ethical reasons not researched much in past (drug abuse, sexual activity leading to HIV); recently, lots of $$ for research • Transmission: • person-person body fluids: sex, drugs, blood transfusions (not always tested in past!!) • Test: ELISA (HIV-AB test) • Social Implications: • Once thought only homosexuals & drug abusers (not so!—rapidly spreading, all at risk) • HIV+ discrimination: employment, insurance, education access, social acceptance, etc. • Not all countries have education/medical treatment to deal w/disease • Inadequate medical care increase in infection rates • Education is key, decrease risk of exposure: GLOBAL problem, needs a GLOBAL solution...not just within the boundaries of our own country.