Disease and Immune Flashcards
what is a disease ?
condition that impairs the normal functioning of an organism
what is a communicable disease ?
disease that can be spread
what organism does ring rot affect ?
potatoes, tomatoes
what organism does black sigatoka affect ?
banana plants
what organism does bacterial meningitis affect ?
just humans
name the three bacterial diseases
TB / bacterial meningitis / ring rot
name the three virus diseases
HIV / influenza / tobacco mosaic virus
name the three fungus diseases
black sigatoka / ringworm / athlete’s foot
name the three protocist diseases
potato blight / malaria
what several ways can direct transmission occur ?
droplet inflection / sexual intercourse / touching infected organism
give examples of pathogens which use direct transmission
- HIV (sex)
- athlete’s foot (touch)
what is indirect transmission ?
disease is transmitted via an intermediate
name the intermediates for indirect transmission
air / water / food / vector (another organism)
give examples of pathogens which use indirect transmission
- potato blight (spores in air, then water)
- malaria (mosquito as vectors)
what are the three factors that affect disease transmission ?
living conditions climate / social factors
how does skin protect from pathogens ?
- acts as physical barrier
- produces antimicrobial chemicals that lower pH, inhibiting pathogen growth
how does mucous membranes protect from pathogens ?
(exposed areas) - secrete mucus which traps pathogens and contains antimicrobial enzymes
how does blood clotting protect from pathogens ?
plug wounds, preventing pathogen entry
how does expulsive reflexes protect from pathogens ?
expels foreign objects
what is inflammation characterized as ?
redness / swelling / heat
what triggers inflammation ?
when tissue is damaged
what happens when tissue is damaged ?
mast cells are activated - releasing histamines and cytokines
what do histamines do ?
- dilate blood vessels, increasing heat at damage site, stops pathogens reproducing
- increases permeability of capillary walls to let neutrophils to pathogens
what do cytokines do ?
attract white blood cells
name some plant physical defences against pathogens
- waxy cuticle
- cell walls
- callose
describe how callose defends plants from pathogens
- callose deposited between cell wall and membrane in times of stress
- callose makes it harder for pathogen to enter cells
name some plant chemical defences against pathogens
- produce antimicrobial chemicals to kill / inhibit growth of pathogen
- secrete chemicals that are toxic for insects to reduce plant viruses carried by insect vectors
what are the two types of phagocytes ?
neutrophil and macro phage
what is a phagosome ?
pathogen enclosed in a membrane in a phagocyte
what is a phagolysosome ?
lysosome fused with a phagosome
phagocytes are …
non - specific
what is special about macrophages ?
they keep some of pathogens antigens, which they attach to the glycoproteins MHC
what does MHC stand for ?
major histocompatibility complex
what does MHC do ?
- moves to plasma membrane of macrophage and puts antigens into membrane
- cell is now antigen - presenting
what does antigen - presenting mean ?
‘shows’ antigens to cells of specific immune system (lymphocytes), activating them
what are opsonins ?
- bind to pathogens and identify them to phagocytes
- most are antibodies / immunoglobulins produced by lymphocytes
define natural immunity
occurs naturally without medical treatment
what processes do T lymphocytes undergo ?
clonal selection + clonal expansion
what is clonal selection ?
- antigen (from APCs) binds to complementary receptors of T lymphocyte
- (T lymphocytes are specific)
what is clonal expansion ?
divides to produce clones of itself
what is function of T helper cells ?
release substances (interleukins) to activate B lymphocytes and T killer cells
what is function of T killer cells ?
attach and kill cells infected with a virus
what is function of T regulatory cells ?
- suppress immune response from other WBCs
- this helps stop immune system cells attacking host’s body cells
what do some T lymphocytes become… ?
memory cells
how are B lymphocytes activated ?
- complementary antigen binds to antibodies on lymphocyte (antigen-antibody complex)
- interleukins released from T helper cells binds to B lymphocyte receptors
what happens to B lymphocytes once activated ?
divide by mitosis into plasma cells / memory cells
what is the function of plasma cells ?
secrete antibodies
what are the three things antibodies do ?
agglutinate / neutralise toxins / prevent pathogen from binding to human cells
what does it mean that antibodies agglutinate pathogens ?
- has two binding sites, so can bind to two, causing them to clump
- means phagocytes can engulf multiple at a time
- this antibodies are known as agglutinins
why is primary response slow ?
- not many B lymphocytes ready to make antibodies
what cells are activated in primary response ?
B and T lymphocytes
what cells are activated in secondary response ?
memory cells
what is the nucleus + cytoplasm of a neutrophil described as ?
multi - lobed + grainy
what does a lymphocyte look like ?
small, nucleus takes up most of cell
what is the biggest white blood cell called ?
monocyte
what is an autoimmune disease ?
immune system treats self antigens as foreign, and launches an immune response against its own tissue
what is herd immunity ?
vaccinating most people in a community
what is immunization ?
process by which you develop immunity
what is vaccination ?
administration of antigens
why are booster vaccines given later ?
to make sure memory cells are produced
why does the influenza vaccine change every year ?
antigens of influenza changes regularly, so will not be recognized by memory cells
give function of variable region in antibody
antigen binding site
give function of constant site in antibody
binding site to receptors of phagocytes
give function of disulfide bridge in antibody
holds polypeptide chains together
give function of hinge region in antibody
allows flexibility when binding
state the 4 differences between active and passive immunity
- active requires exposure to antigens (passive doesn’t)
- active takes for protection to develop, active is immediate
- active is long term, passive is short term
- active memory cells produced, passive there aren’t
define health
disease free, good nutrition, physical mental social well being
what to say with growth of bacteria
multiply / divide not growth
what is irradiation
way of destroying pathogen DNA
what is pickling
lower pH to denature pathogen enzymes
increased fats cause
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