immunology

Question 1

discuss the role and types of toxins

Answer 1

microbes often have toxins which cause cell death of host by lysis. inhibit synthesis, activate enzymes, change hormones levels
the host then secretes products which damage neighbouring cells

endotoxins; inside bacterial cell wall. bind to hsot receptors and case an internal response
exotoxins;toxins secreted by pathogen

Question 2

state three ways apthogens cause damage to host

Answer 2

cause cell lysis by secreting toxins
physical blockage; heartworm in dogs
kill hsot directly

Question 3

how long does it take viruses and bacteria to replicate

Answer 3

viruses; under an hour

bacteria; hours-weeks

Question 4

discuss ways a pathogen can enters the body

Answer 4

inhalation; influenza
ingestion; salmonella
sexual acts; gonorrhea
skin breakage; mosquito bites cause itching.

Question 5

what are symptoms of an invasion

Answer 5

coughing
fever
loss of apetite
swelling
fatigue

Question 6

why is mammal pregnancy a challenge

Answer 6

the featus is 50% ‘‘non self’’ which opens it up to possible immune system attack

Question 7

what are the 5 stages involved in responding to an infection

Answer 7

realising the pathogon is present
innate response
aquired response
pathogen elimination
immunity

Question 8

how does a host become aware of an infection

Answer 8

it has macrophages positioned at strategic places in the body which are capable of detecting exotoxin production

Question 9

discuss the physcial and chemical defences in place to prevent most pathogens entering the body and causign pathogenesis

Answer 9

physical;
thick layer of skin with tough fiberous keratin proteins
mucus membranes in respiratory tract along with cilia

chemical;
stomach contains hydrochloric acid
dilute acid in urinary tract
lysozymes in tears and sweat; an enzyme which kills bacteria
the fatty acids in skin have antibacteiral qualities

Question 10

discuss the inflammatory response as part of the innate immune response

Answer 10

1) macrophages are activated and perform phagocytosis, release molecules
3) mast cells and platelets are activated which release histamine which causes increases permeability of blood vessels and vasodialation which causes more white blood cells to come to the scene
4) natural killer cells are activated
5) clotting system
6) complement system

overproduction of cytokines occurs which causes release of cytokines into the systemic circulation system; other organs respond. fever, fatigue, anorexia,

Question 11

discuss how macrophages perform phagocytosis

Answer 11

they extend projections around the microbe and engulf it in a vesicle. the vesicle then fuses with a lysosomal vesicle which causes the pathogen to be degraded (its protein is broken into smaller peptides via proteolytic enzymes)

Question 12

what is an opsonin

Answer 12

a protein needed for a macrophage to engulf a pathogen. it forms a bridge between the macrophage and the pathogen

Question 13

discuss the role of macrophages during the inflammatory innate response

Answer 13

phagocytosis

release cytokines

release platelet activation factor which activates platelets which begin producing histamine; this causes vasodialation and increases permeability to WbC’s and protein

release prostaglandins

cause activation, differentiation and proliferation of T and B cells

activate mast cells

Question 14

discuss the role of natural killer cells

Answer 14

these are activated by cytokinins
kill Tumour cells and pathogen infected cells (cytotoxic) by producing proteases, releasing perforins into the cell wall which causes pores to open in the wlal and the cell to burst

Question 15

discuss the different types of cytokinins

Answer 15

interleukin; activation and proliferation of T, B and NK cells

interferon; inhibit viral infections by activating macrophages and neutrophils. a virus enters a cell and the cells releases interfearon to cause neighbouring cells to begin expressing anti viral enzymes

tumour necrosis factor (TNF); inhibits viral replciation

chemokine; controls movement of cells between tissues

colony stimulating factor; causes bone marrow to differentiate and proliferate into different cells.

Question 16

describe the acute phase response

Answer 16

this is a mechanism which involves cytokines being released into systemic circulation which reach the liver and cause it release positive acute phase proteins which inhibit microbial growth. negative acute phase proteing are those whos concentrations decrese in response to inflamation so that the amino acids can be conserved for positive phase protein synthesis

Question 17

discuss the aquired immune response to pathogen invasion

Answer 17

humoural response
B cells release antibodies which bind to extracellular pathogens. complement protein then binds to antibodies and causes the cell to burst open

cell mediated response
macrophages perform phagocytosis of infected cells and present antigens (APC’s).

T helper cells bind to the APC’s and release cytokines to activate B cells and cytotoxic T cells which kill infected cells

Question 18

how to Tc cells kill infected cells

Answer 18

activate nucleases in the cell

Question 19

describe how long the aquired immune response takes

Answer 19

days-weeks.
primary aquired response; lag, log, plateau, decline
secodnary aquired response; decline, log, decline.

Question 20

how does exposure result in immunological memory

Answer 20

memory B cells are produced

Question 21

discuss the difference between active and passive immunity

Answer 21

active; host produces response and generates it own antibodies or Tc cells
passive; host doesnt generate its own resposne; is given antibodies or Tc cells

Question 22

where do T and B cells mature

Answer 22

thymus (gland between lungs)

bone marrow

Question 23

describe the structure of an antibody

Answer 23

Y shaped
glycoprotein
4 chians (2 heavy and 2 light)
hinge region
constant region

Question 24

what is the function of an antibody

Answer 24

act as an opsonin between a pathogen and a phagocyte.

Question 25

where does an antibody bind to on a pathogen and a phagocyte

Answer 25

the antibody binds to the antigen epitope of a pathogen | the Fc region of the antibody binds to the Fc receptor of a phagocyte which initiates pahgocytosis

Question 26

how many B lymphocytes exist

Answer 26

100 million

Question 27

discuss the 5 classes of antibodies

Answer 27

IgM; first antibody made forms a pentamer has class switch ability; G, A, E IgA; protects mucosal surfaces is secreted in milk and therefore gives infacts their initial passive immunity can form dimers IgG highest concentration in body good opsinisation only antibody which can travel across the placenta can neutralise toxins by binding to their active site IgD is bound to B cell surface and signals that the B cell is mature IgE involved in allergies involved in immune response against parasites is on mast cells; when the antibody binds to a pathogen the mast cell releases histamine

Question 28

what do blood groups mean

Answer 28

it is the antigen molecule on your RBC's. A type has A antigens and anti B antibodies B is the opposite of A AB has A and B antigens and no antibodies O has no antigens but both antibodies. can give blood to anyone but can only recieve blood from another O

Question 29

whats another important thing to consider when doing a blood transfusion

Answer 29

the rhesus factor of the giver/recipient | over 30 Rhesus antigens exist

Question 30

how do pathogens evade the immune response

Answer 30

occupy intracellular sites; inside of cells that cant be attacked by the immune system cover themselves in the hosts macromolecules or mimic hsot macromolecules alter gene expression so that antigens presented change constantlys suppress the host immune system; stop production of immune cells or secrete enzymes which stop an immune response evolve in a way so that host molecules cause growth rather than death

Question 31

how do intracellular pathogens avoid phagocytosis

Answer 31

stop the phagosome and lysosome from fusing escape form the phagosome resist death in the pagosome

Question 32

how do extracellular pathogens avoid the immune response

Answer 32

secrete proteases to degrade the antibody or alter the antibody so that opsonisation cant happen produce surface molecules which bind to the antibody and mean the antibody cant bind to the phagocyte. protein A and protein G secrete toxins which kill the phagocyte or make it unable to move have surface structures which stop phagocytosis happening; pilli, capsule

Question 33

discuss 3 examples of antigenic variaiton

Answer 33

microbe has genomic rearrangement which causes a sudden shift in antigens presented microbes have DNA replicating enzymes prone to error so that the antigen composition changes gradually as a microbe matures it changes its composition of antigens so its one step ahead of the immune system

Question 34

whats requried for antigenic variation

Answer 34

multiple antigens switching ability multiple antigen sequences

Question 35

discuss the case of T. brucei

Answer 35

a protozoa with over 1000 antigens 99% of population die then 1% switch antigens and begin thriving and evading humeral response pathogen is transmitted by Tseste fly and causes african sleeping sickness;25,000 deaths a year treatment involves anti parasitic drugs

Question 36

define specificity in relation to immunological test principles

Answer 36

an antibody will only combine with a single antigen

Question 37

discuss cross-reactivity in relation to immunological test principles

Answer 37

some antibodies have the ability to bind with more than one antigen

Question 38

describe the agglutination test and discuss its pros/negs

Answer 38

measures amount of Ab/Ag present a latex bead with Ab's attached is added to serum. if antigens are present they will clump up on bead and agglutinate simple and quick but has little sensitivity

Question 39

what is titer in relation to immunological tests

Answer 39

the reciprocal value of the most dilute solution leading to a positive immunological test result. worked out so that immunological tests are quantifiable

Question 40

describe the complement fixation test

Answer 40

measures quantities of Ab present serum is mixed with known quantities of Ag and complement protein. the amount of unbound antigen/ complement indicates amount of antibody present

Question 41

describe the precipitation test

Answer 41

measures presence of Ab/Ag visible observation of precipitated Ag-Ab signals quantities of molecules present not very sensitive; large amount of AB/Ag must be present for a positive result

Question 42

describe the ELISA test

Answer 42

a test whcih can be used to detect Ab, Ag, toxins, hormones etc the ELISA plate has an antibody bound to an emzyme in a way that the presence of an antigen causes a substrate to be converted to a product which causes a colour change reaction to occur which can be measured used spectrophotometry

Question 43

discuss the types of ELISA test that exist

Answer 43

direct ELISA indirect; secondary antibody sandwich; third antibody competitive; inhibitor antibody leading to no colour change reaction

Question 44

discuss limitations of ELISA

Answer 44

positive result may just mean patient has been infected in the pst false negative results are possible if the body is a bad producer of the antibody or if competing substances for antibody exist false positive results are possible due to cross reactivity

Question 45

what is western blotting used for

Answer 45

detection and quantification of a protein | used to confirm the results of an ELISA test

Question 46

define self reactive lymphocyte

Answer 46

a one which attacks the bodies own cells

Question 47

why do the 2 explanations of why disease occur? more specifically, what are 3 explanations of why autoantibodies are produced>

Answer 47

usually an environmental event activates self reactive self-lymphocytes.a microbial invasion occurs which activates B and T cells complimentory to the microbes antigen. the microbes are also reactive against the bodies own ''self antigen'' rarely its genetic 1) cross reactive epitopes; a pathogen has a similar epitope on its antigen to a self antigen so B cells recognise self material 2) severe host tissue damage such as burns cause self antigens to be released which are taken up by dendritic cells and which causes autoreactive Th cells to be activated 3) mitogens stimulate B cells to produce antibodies for self antigens

Question 48

discuss 3 examples of autoimmune diseases

Answer 48

type 1 diabetes; B cells attack islets of langerhans so the body can no longer produce insulin multiple sclerosis; body attacks CNS haemolytic anaemia; antibodies attacking RBC's

Question 49

what is myasthenia gravis

Answer 49

autoimmune disease autoantibodies are produced which bind to the acetylcholine receptor and block it. electrical signals cant be passed on so muscle contraction cant occur. the autoantibodies also degrade the receptor

Question 50

what is graves disease

Answer 50

an autoimmune disease in which autoantibodies bind to throid tissue and cause excessive expression of thyroid hormones

Question 51

what is hashimotos thyroiditis

Answer 51

T cells and B cells invade the thyoid and casue destruction leading to loss of hormone production

Question 52

what is pernicious aneamia

Answer 52

when autoantibodies are prodcued which bind to floating intrinsic factors in the stomach and blocks B12 from binding to them so vitamin b12 cant be absorped

Question 53

discuss function of dendritic cells

Answer 53

cells that drink body fluids and then present antigens on their surface for Th cells

Question 54

what % of industrialised countries are effected by autoimmune diseases

Answer 54

5%