EMS lectures 11,12,13,14 Flashcards Preview

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Flashcards in EMS lectures 11,12,13,14 Deck (51):
1

define pathogenicity

capability of micro-organism to cause an infection

2

what are the requirements of pathogenicity

transmissibility
establishment in host
harmful effects
persistence

3

what is the chain of infection

pathogenic organism --> reservoir (multiplication) --> exit source --> transmission to host --> entry into host --> host infected

4

Virulence

degree to which microorganism can cause disease

enables relative comparison of pathogenic potential

5

What are virulence factors

components of micro-organism that result in harmful effects

6

what are virulence mechanisms?

Facilitation of adhesion
toxic effects
tissue damage
interference with host defence mechanism
facilitation of invasion
modulation of host cytokine reactions

7

what are bacterial endotoxins

part of gram negative cell wall,
active component = LPS Lipopolysaccharide
- released from dead/damaged cell walked and bind to host cell receptors
induce uncontrolled cell response =

8

What are bacterial exotoxins

protein produced in living bacteria
- produce specific host effect

9

Explain Systemic inflammatory response syndrome (SIRS)

host response to endotoxin
- uncontrolled t lymphocytes
- uncontrolled activation of clotting cascade
- uncontrolled activation of complement

cardiac/renal failure, hypotension, tachycardia, bleeding tendency, collapse, fever

10

What anaerobe causes Botulism
- how can you contract botulism
- what is the presenting complaint with botulism

Clostridium botulinum
- contaminated food/dirty wound

PC = diplopia, dysphagia, dysarthria, dry mouth, death

11

What causes Tetanus
- what is the toxin
- what is the action
- what is the common cause of death

Clostridium tetani
- Tetanospasm
- inhibits neurotransmitters in CNS
Death by respiratory paraylisis

12

Other diseases caused by exotoxins

Cholera
diptheria
whooping cough
c.dif
e.coli
scarlet fever

13

What are to virulence factors of Streptococcus pyogenes

- promote connective tissue invasion and breakdown

- Hyaluronidase and streptokinase - break down connective tissue
-C5a peptidase - inactivates complement component C5a
- Erythrogenic toxin - causes scarlet fever rash
Toxic shock syndrome toxin -
similar to syndrome of endotoxin release

14

How does S pyogenes and S pneumonia inhibit phagocytosis

Pyogenes - M protein binds fibrinogen and masks bacterial surface

Pneumoniae - polysaccharide capsule inhibits opsonisation

15

What are the components of a virus

genome (RNA or DNA)
capsid - protein
envelope

unable to exisit without host

16

Define atherosclerosis

degeneration of arterial wall - characterised by fibrosis, lipid deposition and inflammation -limit blood circulation and predisposes to thrombosis

17

What are the risk factors for artherosclerosis

age, male, family history, genetics

hyperlipidaemia, hypertension, smoking, diabetes,

18

Describe atherosclerotic plaque formation

1) damage to intima of vessel
2) lipid accumulation in intima
3) monocyte migration and ingestion of lipids in intima
4) monocytes become foam cells
5) foam cells secrete cytokines - attrack macrophages, lymphocytes, smooth muscle cells
6) formation of atherosclerotic plaque
7) plaque grows - occludes vessel, weakens vessel wall = aneurysm, erodes vessel

19

What are the differences between a clot and a thrombus

Clot
- stagnant blood, enzymatic process, elastic, adopt vessel wall shape

Thrombus
- w/i body during life, platelet dependant, firm

20

What are platelets
- what do they secrete

Fragments of megakaryocytes
bind to collaged exposed by endothelial damage and become activated

secrete alpha granules - fibrinogen, fibronectin
dense granules - chemotactic chemicals

21

Define Embolus

mass of material able to lodge in vessel and block it
can be endo/exogenous

22

What is the commonest emboli
- risk factors
- effect of size

Pulmonary emboli
- Factor 5 leiden deficiency, Protien S deficency
- smoking, pregnancy, obesity, heart failure, immobility,

SMALL - pulmonary hypertension
medium - V/Q mismatch, cardiac/ resp failure
Large = death - saddle emboli

23

What is a systemic emboli

arise with in heart and arterial circulation

24

What is an infective emboli

usually from infected heart vales
- effects compounded by infective nature - lead to mycotic aneurysm formation

25

What is a tumour embolism

parts of tumour break of when penetrating wall - route for dissemination

26

What are the types of gas emboli and when do they occur?

Air - vessels opened to air
- obstetric procedures
- chest wall injury
>100ml to cause clinical effects

Nitrogen - decompression sickness - the bends

27

Explain what an amniotic fluid embolism is
- frequency
- causes

increased uterine pressure causes amniotic fluid into maternal uterine veins
= 1:50,000
- lodge in lungs --> resp distress


28

what is the common cause of a fat embolism
- % fatality
- what does it cause

- trauma
- 15%
- sudden resp distress

29

How can foreign body emoblism occur
- common in who?
- lead to?

particles injected IV
- IVDU
- granulomatous disease

30

define hypoxia

state of reduced tissue oxygen availability

31

Define ischaemia

pathological reduction in blood flow to tissue
results in tissue hypoxia

32

How harmful is ischaemia

short duration - cell injury reversible

prolonged - cell death by necrosis = irreversible cell damage

33

When will therapeutic reperfusion work?
What happens if ischaemic tissue is reperfused?

- is ischaemia is reversible

- reactive o2 species will call further cell damage = reperfusion injury

34

define infarction
- common causes

ischaemic necrosis caused by occlusion
- thrombosis, embolism
- vasospasm, atheroma expansion, volvulus, AAA,
- venous occlusion

35

Morphology of infarction
- how is it classified

Classified by colour
Red infarction - hemorrhagic
- dual blood supply/venous infraction

White infarction -anaemic
- single blood supply therefore totally cut off

36

define shock

systemic reduction in tissue perfusion
decrease in o2 delivery to tissues
-imbalance o2 delivery and consumption
- leads to cellular hypoxia

37

what are the cellular effects of shock

membrane ion pump dysfunction
intracellular swelling
leakage of centents
inadequate regulation of intracellular pH
anerobic respiration - lactic acid

38

What are the SYSTEMIC effects of shock

alterations in serum pH
endothelial dysfunction - vascular leakage
stimulation inflammatory and antiinflammatory systems
end - organ damage

39

Explain hypovolaemic shock
- presentation
- causes
- what happens

Intra-vascular fluid loss
lower venous return to heart, lower stroke vol, decreased cardiac output
Increased stroke vol rate (vasocontriction)

present - cool, clammy, shut down
causes - haemorrhage, diarrhoea, vomiting, heatstroke, third spacing

40

What is third spacing

loss of fluid into internal body cavities

41

explain cardiogenic shock

cardiac pump failure
- low Cardiac Output
- increased Stroke vol rate

- myopathic - muscle failure
-arrythmia related - abnormal beats
- mechanical
- extra-cardiac - obstruction
60-90% mortality

42

explain distributive shock

severe vasodilation - low SVR
increase Cardiac Output
- flushed bounding heat

= septic shock, anaphylactic shock, neurogenic shock, toxic shock syndrome

43

explain anaphylactic shock

type 1 hypersensitivity reaction
vasodilation

44

neurogenic shock

spinal injury, loss of sympathetic vascular tone
vasodilation --> shock

45

toxic shock syndrome
- cause

exotoxin - s.aureus, s.pyogenes
nonspecific binfing of class 2 MHC to T cell receptors
massive cytokine activtion - decrease SVR

46

How common is inborn metabolic disease

RARE
1-2000 live births

47

What are the clinical effects of hyperammoneaemia toxicity
- what is the cause

ammonia accumultion dyr to urea cycle defect

-lethargy, poor feeding, vom, thachypnoea, convulsions, coma, death

48

what accumulates in porphyrais
- signs acute porphyria
- signs photosenstive porphyria

Porphyrins

Acute
= Abdo pain, vom, insomnia, palpatatoin, HBP, anxiety, seizure,breathing probs, red/brown urine, muscle pain

Photosensitve porphyria
- sensitivity to sun, painful erythema, blisters, itching, fragile skin, inc hair growth, red/brown urine

49

when can inborn errors of metaboilism be diagnosed

Presymptomatic population screening

Investigation of symptomatic individuals

50

Test for inborn errors of metabolism

urine metabolic screening

51

What prenatal screening is available
- neural tube defect
- down syndrome

Neural tube defect
- 16 week ultrasound, maternal serum and Amnoitic fluid AFP

Down syndrome
- 1st trimester - PAPA, HCG, nuchal translucency
- 2nd trimester - maternal serum AFP, HCG, inhibin and estrol