Ischaemia, Infarction and Shock

Question 1

What is the name given to any state of reduced tissue oxygen availability?

Answer 1

Hypoxia

Question 2

What is the name given to the pathological reduction in blood flow to tissues .
(usually as a result of obstruction to arterial flow by thrombosis/ embolism)

Answer 2

Ischaemia

Question 3

Ischaemia results in …

Answer 3

hypoxia

Question 4

In prolonged ischaemia, irreversible cell damage occurs. What is the process of cell death?

Answer 4

Cell death occurs by necrosis (infarction) in sustained ischaemia

Question 5

When is therapeutic reperfusion effective in ischaemia?

Answer 5

Tissue perfusion is good if ischaemia is reversible. (short duration of ischaemia)

Question 6

what is reperfusion injury?

Answer 6

generation of reactive oxygen species by inflammatory cells causes further damage when reperfusing ischaemic tissues.

Question 7

what is the name given to the tissue damage caused when blood supply returns to the tissue after a period of ischemia or lack of oxygen (anoxia, hypoxia).

Answer 7

reperfusion injury

Question 8

What is ischaemic necrosis caused by occlusion of the arterial supply or venous drainage?

Answer 8

Infarction

Question 9

What are the main causes of Infarction?

Answer 9

• thrombosis
• embolism
• Vasospasm
• compression of vessel
• Vaculitis
• rupture of vascular supply (AAA)

Question 10

What shape are most infarctions?

Answer 10

wedge shaped

Question 11

where does colliquative necrosis normally occur?

Answer 11

brain

Question 12

What factors influence the degree of ischaemic damage?

Answer 12

1) nature of blood supply
2) rate of occlusion
3) Tissue vulnerability to hypoxia
4) Blood oxygen content

Question 13

What organs have a single blood supply which makes them vulnerable to infarction?

Answer 13

1) Kidneys
2) Spleen
3) Testis ect.

Question 14

What organs have an alternative blood supply which maked them less prone to infarction via ischaemia?

Answer 14

1) Lungs (pulmonary and bronchial arteries)
2) Liver (hepatic artery and portal vein)
3) Hand (Radial and ulnar artery)

Question 15

Slow developing occulsions are………………likely to infarct tissues

Answer 15

LESS

Slow developing occlusions are less likely to infarct tissues because:
-it allows time for development of alternative (collateral) perfusion pathways.

Question 16

What organ requires 15% of cardiac output and 20% of body oxygen?

Answer 16

Brain

Question 17

What is the name given to any abnormality of the brain caused by pathological process involving the blood vessels?

Answer 17

Cerebrovascular disease

Question 18

Give an example of a cerebrovascular accident?

Answer 18

Stroke

Question 19

what causes an ischaemic stroke?

Answer 19

• thrombosis secondary to atheroscelrosis

- embolism

Question 20

What causes haemorrhagic stroke?

Answer 20

• intracerebral haemorrhage (hypertensive)

- Ruptures aneurysm in the circle of willis&raquo_space;>subarachnoid haemorrhage

Question 21

What is the site of the thrombosis or embolism that causes ischaemic bowel disease?

Answer 21

Superior or Inferior mesenteric arteries

Question 22

Infarction of entire portion of limb (organ)

Answer 22

Gangrene

Question 23

what type of gangrene has ischaemic coagulative necrosis only?

Answer 23

Dry Gangrene

Question 24

what is the characteristic feature of wet gangrene?

Answer 24

superimposed infection

Question 25

what is the characteristic feature of gas gangrene?

Answer 25

superimposed infection with gas producing organism e.g. clostridium perfringens

Question 26

what is the name given to the physiological state characterised by a significant reduction of systemic tissue perfusion (SEVERE HYPOTENSION), resulting in DECREASED OXYGEN DELIVERY TO TISSUES

Answer 26

Shock =hypotension and decreased oxygen delivery

Question 27

What results in a critical imbalance between oxygen delivery and oxygen consumption?

Answer 27

Shock

Question 28

impaired tissue perfusion and prolonged oxygen deprivation leads to ....?

Answer 28

cellular hypoxia

Question 29

What are the cellular effects of shock?

Answer 29

1) membrane ion pump dysfunction 2) Intracellular swelling 3) leakage of intracellular contents into extracellular space 4) inadequate regulation of intracellular pH 5) Anaerobic respiration >>>lactic acid

Question 30

What are the systemic effects of shock?

Answer 30

1) alterations in the serum pH 2) Endothelial dysfunction >>> vascular leakage 3) Stimulation of inflammatory and anti-inflammatory cascades 4) end organ damage (ischaemia)

Question 31

what is the sequential result of shock

Answer 31

- cell death - end organ damage - multi organ failure - death

Question 32

what are the different types of shock?

Answer 32

1) hypovolaemic 2) Cardiogenic 3) Distributive - anaphylactic - septic - toxic shock syndrome - neurogenic

Question 33

What kind of shock can be attributable to : - intravacular fluid loss (blood,plasma) - decreased venous return to heart (ie. decreased pre-load) - therfore decreased stroke vol and decreased cardiac output.

Answer 33

Hypovolaemic shock

Question 34

How to compensate for hypovolaemic shock?

Answer 34

increase vasoconstriction | -this increases total peripheral resistance

Question 35

What are the causes of hypocolaemic shock?

Answer 35

1) Haemorrhage 2) Non-haemorrhagic fluid loss e.g. diarrhoea, vomiting Reduces circulation volume

Question 36

what are the causes of cardiogenic shock?

Answer 36

1) Myopathic (heart muscle failure) 2) Arrythmia-related (abnormal electrical activity) 3) Mechanical 4) Extra cardiac (obstruction to blood outflow)

Question 37

What kind of shock is caused my MI, right ventricular infarction, stunned myocardium?

Answer 37

Myopathic cardiogenic shock

Question 38

what causes vasodilation in septic shock?

Answer 38

increased cytokines and mediators released by the immune reaction

Question 39

What happens in anaphylactic shock?

Answer 39

1) sensitised individuals exposed to stimulus 2) IgE mediated 3) Mast cell degranulation leads to histamine release 4) vasodilation 5) contraction of bronchioles 6) laryngeal oedema

Question 40

What happens in neurogenic shock?

Answer 40

1) spinal injury leads to 2) loss of sympathetic vascular tone 3) Vasodilation 4) Hypovolaemia 5) Shock

Question 41

What organisms release exotoxins that causes Toxic Shock syndrome?

Answer 41

Staph Aureus | Staph Pyogenes