Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

K Cards > PATH 13 - ISCHAEMIA & INFARCTION > Flashcards

PATH 13 - ISCHAEMIA & INFARCTION Flashcards

1
Q

What is Ischaemia

A

Reduced blood supply and/or increased tissue requirements but no necrosis
•Characterised by insufficiency of O2, lack of nutrient substrates and inadequate removal of metabolites (perfusion)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What determines which types of tissue/organs are more likely to be susceptible to ischaemia?

A

1.Poor blood supply e.g. atheromatous arterial supply

2 Presence or absence of Collateral circulation – (latter may compensate for reduced perfusion)
>Good collateral circulation:
Liver, lung, bowel, brain (arterial anastomoses)
>Poor collateral circulation
Kidney, spleen +/- heart

3.Tissue metabolism Requirements
Organs with high metabolic rate and aerobic metabolism–more susceptible (heart)
Supporting tissues (fibrous, bone) – less susceptible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What tissues are susceptible to ischaemia?

A

Vulnerable tissues
‘Watershed’ areas (esp. during shock/hypotension)
Splenic flexure of the colon
Brain
Deep myocardium
Portal’ vasculature 1 main supplying artery pituitary, renal,exocrine pancreas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Briefly explain reperfusion injury

A

Restoration of blood flow after ischaemia may cause a paradoxical increase in cell injury

This is due to:
•Formation of free radicals following restoration of O2 supplied to cells
•Failure of Ca2+-ATPase pumps - cells unable to control levels of cytosolic calcium and accumulation in mitochondria
•Excess calcium causes loss of cell integrity and cell necrosis

Clinically relevant with haemorrhage into cerebral and myocardial infarcts
Amenable to therapeutic intervention e.g. Tx: calcium channel blockers to slow the re-entry of Ca into cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is infarction

A

Cell/tissue death due to reduced blood supply
•Area of ischaemic necrosis caused by occlusion of either the arterial supply or the venous drainage in a particular tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Define necrosis

A

Cell death in living tissue.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the common clinical Illnesses due to Infarction

A
  • Myocardial infarction
  • Cerebrovascular accident (infarct)
  • Pulmonary infarction
  • Bowel infarction
  • Ischaemic necrosis of the extremities
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the causes of Ischaemia & Infarction Reduced blood supply?

A

Shock
•Hypotension
•Septic
•Cardiogenic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Name the conditions associated with obstruction of blood vessel

A

1.ATHEROSCLEROSIS
2.THROMBOSIS
3.EMBOLUS
Other
>Vasculitis
>Local vasospasm e.g. cocaine
>Extrinsic compression of vessel
>Extrinsic compression of blood supply by oedema or entrapment (hernia)
>Torsion of vessel (testis)
>Traumatic rupture of blood supply

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Differentiate between Thrombosis and Embolus

A

Thrombosis: Solid mass in flowing blood
Embolus: Solid or gaseous or liquid mass that moves from one part of the circulation to another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the causes of Thrombi?

A
  • Virchow’s Triad
  • Endothelial damage
  • Hypercoagulability
  • Stasis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

State the different types of emboli

A
  • Thrombus
  • Tumour
  • Septic
  • Fat
  • Air
  • Cholesterol
  • Foreign Body
  • Nitrogen
  • Amniotic fluid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What types of Infarcts do you know

A 
RED (Red blood cells)
    Loose tissues (lung)
    Venous occlusion (ovary)
    Dual circulation (intestine)
    Reperfusion (Flow reestablished)
WHITE
    Solid organs
•    Heart
•    Spleen
•    Kidney
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the Macroscopic appearances of infarct in the different stages.

A

Wedge shaped (occluded vessel at apex)

EARLY

  • Poorly defined, irregular
  • Narrow rim of hyperaemia at edge due to inflam mation/repair

LATE
Solid organ (white)
Few RBCs lysed 🡪 some hemosiderin pigment
Pale and sharply defined

Spongy organ (red)
Firm and brown
Hemosiderin pigment
Pale and sharply defined

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the likely causes of cell damage?

A
  • Infarction
  • Inflammation
  • Infection
  • Immune
  • IrritantIdiopathic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

State Microscopic features of infarcts

A

> May be little in first 12 to 18 hrs, only haemorrhage (if
patient survives)
Necrotic tissue stimulates inflammatory response at edge (1-2days)
Phagocytosis of cellular debris and dead tissue
Reparative phase with scar formation

17
Q

What are the consequences of a scar/fibrosis of the myocardium following an infarct?

A

> Loss of muscle pump function

>Left ventricular failure

18
Q

Write a brief dummary of tissue changes following infarction (response to necrosis)

A 
Cell necrosis
Acute inflammation
Chronic inflammation
Granulation tissue
Scar

{note > must be able to define all these}

19
Q

State the types of necrosis

A
  • Coagulative – MI
  • Liquefactive – Stroke
  • Gangrenous - Diabetes
  • Fat necrosis – Trauma to fat
  • Caseous - TB
20
Q

Briefly describe the Factors determining degree of infarction

A

• Availability of alternative blood supply
e.g lungs, liver, vs kidney, spleen

•Rate of development of occlusion
e.g. coronary arteries & atherosclerosis

•Vulnerability of tissue
Neuron(3-4mins) vs Myocyte (20-30mins) vs Fibroblast (hours)

•Oxygen content of blood – anaemia increases likelihood of ischaemia

21
Q

Compare and contrast Ischaemia and hypoxia

A

Hypoxia: oxygen deficiency, causes cell injury
Ischaemia: loss of blood supply due to impeded arterial flow or venous drainage
Ischaemia is the most common cause of hypoxia

22
Q

Name Arterial disorders

A

• Atherosclerosis
• Arteriolosclerosis (smaller arterioles)
• Hypertension
Increases risk of atheroma Why?
Causes thickening of arterioles (arteriolosclerosis)

• Vasculitis: Subject of another lecture but
Remember vasculitis is inflammation of vessel wall
Can be artery, arteriole or venous or capillary
Often caused by an immune reaction
Causes thrombus and reduction in blood supply to organ supplied by vessel
• Aneurysms of heart or arteries

23
Q

State the disorders of Capillaries and Veins

A

Capillaries
No media: thin wall for gas exchange.
Capillaries classically damaged by the vasculitis and/or microemboli/thrombi.

Veins
• Low pressure blood reservoir.
• Decreased muscle and elasticity compared to arterial system.
• Because of lack of pressure drive need valve system to prevent incompetence: e.g. veins of the leg
• Major disease process is Thrombosis.
• Very rarely atheroma

K Cards (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions