Week 11

Question 1

what is type 1 hypersensitivity?

Answer 1

IgE mediated hypersensitivity - IgE bound to mast cells via Fc portion

Question 2

what is type 2 hypersensitivity?

Answer 2

Ab mediated cytotoxic hypersensitivity

- cells are destroyed by bound Ab either by activation of complement or cytotoxic T cell (ADCC)

Question 3

what is the biphasic response in effector phase of type 1 hypersensitivity?

Answer 3

initial: preformed mediator release (vasodilation, vascular leakage, SM spasm)
late phase: inflammatory cell influx (mucosal edema, music secretions, leukocyte infiltration, epithelial damage, bronchospasm)

Question 4

where dose mast cell degradation and activation occur in type1?

Answer 4

GIT
nasal passage, eyes, airways
BV

Question 5

what is type 3 hypersensitivity?

Answer 5

immune complex hypersensitivity
Ag:Ab complexes are deposited into sites of tissues which activates complement and attracts more neutrophils to the site of infection

Question 6

what is type 4 hypersenstivity?

Answer 6

cell mediated hypersensitivity

Th1 cells secrete cytokines and activate macrophages which can accumulate at the site and CTLs

Question 7

what are some immune complex related disease?

Answer 7

bacterial
viral
parasitic
autoimmune
serum sickness

Question 8

how does a hapten work?

Answer 8

it can only trigger an immune response when coupled with an Ag
small molecules that contact skin and bind host proteins and converting that self Ag to highly immunogenic foreign peptides- bind to skin APC and activate T cells
upon subsequent exposure that same hapten triggers a memory T cell response

Question 9

what are the 5Rs of radiotherapy?

Answer 9

radiosensitivity 
repair
redistribution 
repopulation 
re-oxygenation

Question 10

what causes acute effects to radiotherapy?

Answer 10

suppression of cell proliferation in tissues with high cell turnover (bone marrow, GI, airway mucosa)

Question 11

what causes the late adverse effects of radiotherapy?

Answer 11

damage to non-proliferating tissues which cannot compensate for cell death

Question 12

what is biphasic response of the effector phase in type 1 hypersensitivity

Answer 12

initial response is <15 min, release of preformed mediators = vasodilation, vascular leakage and smooth muscle spasm

late phase reaction is 4-24 hours, inflammatory influx = mucosal edema, mucosal secretions, leukocyte infiltration, epithelial damage, bronchospasm

Question 13

where are mast cells found?

Answer 13

CT throughout the body, GIT, resp tract, heart

Question 14

when are the connective tissue mast cells degranulated?

Answer 14

intravenous or subcutaneous mast cell degranulation

Question 15

when are the mucosal mast cells degranulated?

Answer 15

inhalation or ingestion of allergen

Question 16

symptoms of mast cell degranulation with intravenous allergen?

Answer 16

widespread histamine release which acts on BV to increase permeability = hives or anaphylactic shock

Question 17

symptoms of mast cell degranulation with subcutaneous allergen?

Answer 17

local histamine release causes wheal and flare (red and swelling)
topical allergen penetrating can also be a cause of atopic asthma

Question 18

symptoms of mast cell degranulation with inhaling an allergen?

Answer 18

allergic rhinitis - due to increased mucus production and nasal irritation

asthma due to contraction of bronchial smooth muscle and increased mucus secretion

Question 19

symptoms of mast cell degranulation with ingestion of allergen?

Answer 19

contraction of intestinal SM induced vomitting

outflow fluid into the gut causes diarrhea

Question 20

clinical signs of anaphylaxis?

Answer 20

pale gums 
cold limbs
increased HR
weak pulse
urticaria (increased V perm)
angioedema 
dyspnoea
hypoxia
hypotension 
contraction of intestinal SM = cramp and diarrhea
swelling of lips, tongue, larynx = block respiration 
bronchoconstriction blocks expiration

Question 21

examples of type 2 hypersensitivity?

Answer 21

incompatible blood transfusion
hemolytic disease newborn
hyperacute graft rejection

Question 22

tx for anaphylactic reaction?

Answer 22

adrenalin which reforms the tight junctions of endothelial cell and relaxation of bronchial SM and heart

Question 23

arthus reaction?

Answer 23

type 3 hypersensitivity
following penetration of Ag locally - ind gets vaccinated but already has pre-existing Ab to this Ag thus forms an immune complex initiating an inflammatory response

Arthus reactions (type III hypersensitivity reactions) are rarely reported after vaccination and can occur after tetanus toxoid–containing or diphtheria toxoid–containing vaccines. An Arthus reaction is a local vasculitis associated with deposition of immune complexes and activation of complement.

Question 24

serum sickness?

Answer 24

eg, snake venom give the ind anti-venom serum however they already have Ab against anti-venom = form immune complex

bitten again = anti-anti venom Ab will bind anti venom serum and cause vasculitis

Question 25

what are haptens?

Answer 25

small molecules that contact skin and bind host proteins thus converting self Ag into highly immunogenic foreign peptide which skin APCs can take up and sensitize naive hapten specific CD4 and CD8 T cells upon subsequent exposure to the same hapten the hapten specific memory T cells in skin are activated = Th1 and CTLs

Question 26

role of Th1 and CTLs in haptens?

Answer 26

Th1 secretes cytokines IFNy which activates macrophages to secrete IL1, IL6 and TNF TH1 also activates keratinocytes which secrete IL1 and TNF

Question 27

example of type 4 hypersensitivity?

Answer 27

mantoux skin test IBD RA MS

Question 28

what is injury prevention?

Answer 28

prevention from an accident from occurring which would have resulted in injury reduction in the exchange of energy thus reducing the severity in injury

Question 29

draw out haddon matrix for road trauma

Answer 29

see notes

Question 30

what is the hierarchy of control? purpose?

Answer 30

system used to minimize and eliminate exposure to hazards | its unlikely people will change unless its made a rule or a law (eg, seat belts)

Question 31

different components of hierarchy of control?

Answer 31

elimination- physically remove hazard substitution- replace hazard engineering controls- isolate people from hazard administrative controls- change the way people work personal protective equipment - protective the work with gloves etc

Question 32

5 steps of project planning?

Answer 32

``` identify the problem analyze the problem design solutions plan your program evaluate (use SMART) - specific, measurable, achievable, relevant, timely ```

Question 33

photon therapy?

Answer 33

``` better for deeper tumours travel in beam like visible light inverse square law entry and exit dose ```

Question 34

electron therapy

Answer 34

for superficial tumours entry dose only small light particles that cannot penetrate all the way

Question 35

what are the signs of early radiation toxicity?

Answer 35

alopecia denudation of skin erythema inflammation caused by suppression of cell proliferation in tissues with high cell turnover radiation causes local damage of DNA in healthy cells and release of ROS

Question 36

what are the signs of late radiation toxicity?

Answer 36

``` microvascular damage fibrosis telangectasia atrophy necrosis LOF hypo/hyperpigmentation glomerulonephritis ``` caused by damage to non-proliferating cells which are unable to compensate for cell death

Question 37

which cancers are sensitive / resistant to radiotherapy?

Answer 37

sensitive: lymphoma, small cell, seminoma resistant: pancreatic, renal, glioblastoma, melanoma

Question 38

why do we fractionate radiotherapy treatment?

Answer 38

to allow hypoxic cells to become oxic (reoxygenation) to allow greater chance of targeting sensitive stages of the cell cycle (redistribution) to allow healthy cells to repair from radiotherapy as tumour cells don't repair (repair)

Question 39

how does radiotherapy work on a molecular and cellular level?

Answer 39

direct damage to DNA: radiation physically breaks sugar phosphate backbones of base pairs of DNA indirect damage to DNA: due to production of toxic free radicals from interaction of radiation with water/ oxygen within cell both result in single and double stranded breaks that if not repaired will accumulate and lead to reproductive death double stranded breaks may persist without accurate repair resulting in mutations

Question 40

external beam radiation therapy

Answer 40

delivered in photon beams

Question 41

internal beam radiation

Answer 41

delivered from radiation sources placed inside or on the body radioactive isotopes sealed in pellets implanted using delivery devices can deliver higher doses to some cancers than some external beam while causing less damage to healthy cells

Question 42

systemic radiation therapy

Answer 42

oral/ parenteral administration of radioactive substance bound to a monoclonal ab used target delivery to specific tissues

Question 43

3 principles to radiation safety?

Answer 43

time distance shielding