Transcript IB Immune Core Topics part 2

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.
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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.