Vascular Disease (week 6) Flashcards
What is the defintion of atheroma?
Intimal lesion that protrudes into vessel wall. Consists of soft lipid core (mainly cholesterol) and covered by fibrous cap.
Which vessels are commonly affected by atheroma?
AA Coronary arteries Popliteal arteries Carotid arteries Circle of willis Any bifurcations (turbulent flow)
Which gender is more likely to have atheroma?
Male
What factros may cause initial damage to inner layer of artery?
hypertension
high cholesterol
irritants e.g. nicotine
diabetes
What type of cells form the initial fatty streak in the intima?
lipid filled foamy macrophages
Name the differences between a clot and a thrombus in:
1) platelets
2) location
3) colour
4) structure
1) platelets only involved in thrombus
2) clots can be in or outside vessel, thrombus is only inside vessl. Clots are not attached to vessel wall, thrombi are.
3) clots are red, venous thrombus is red, arterial thrombus is pale
4) clot = gelatinous, thrombus = firm
Where are likely locations of arterial and venous thrombi, and what diseases are each involved in?
Aterial = left heart chambers, arteries. ACS, ischaemic stroke, claudication. Venous = venous sinusoids of muscle, venous valves. DVT, PE.
How does the composition and therefore treatment of arterial thrombi differ to venous?
Arterial = platelets, treat with anti-platelet agents e.g. aspirin, clopidogrel Venous = fibrin, treat with anticoagulants e.g. warfarin
Define the terms ischaemia and infarction.
Ischaemia: pathological reduction in blood flow to tissues, usually as a result of arterial occlusion. Leads to hypoxia.
Infarction: obstruction of blood supply to tissue resulting in tissue death.
What may cause an infarction?
Occlusion by thrombus / embolus Atheroma expansion Vasospasm Extrinsic compression e.g. from tumour. Twisting of vessel roots e.g. volvulus Rupture of vascular supply
What is the differnece between an infarction that is red in colour and one that is white?
red infarction = haemorrhagic. Venous infarction, blood not drained.
white infarction = anaemic. single blood supply that is totally cut of.
Which type of necrosis is characteristic of infarction?
Coagulative
colliquitive in brain
What is meant by shock?
State of reduced tissue perfusion resulting in decreased oxygen delivery to tissues - decreased mean arterial pressure. Leads to cellular hypoxia.
What causes hypovolaemic shock and what are the consequences?
Intra-vascular fluid loss: haemorrhage, diorrhoea, vomiting, burns
Decreased venous return to the heart (preload) –> decreased stroke volume –> decreased cardiac output. Compensate by vasoconstriction to increase systemic vascular resistance.
What is cardiogenic shock?
Cardiac failure leading to decreased cardiac output.
What might cause cardiogenic shock?
Cardiac myopathy (muscle) Arrhythmia: abnoraml electrical activity Mechanical e.g. valvular defects Extra-cardiac: obstruction to blood flow - anything outside heart that imparis contraction / filling e.g. PE, tension pneumothorax, constrictive pericarditis
What is distributive shock?
Decreased SVR due to severe vasodilation
What is septic shock?
Severe infections with bacteria / fungi cause very high cytokine levels, which stimulate vasodilation.
What is anaphylactic shock?
Severe type I sensitivity reaction where allergen leads to IgE cross-linking causing mast cell degranulation. This leads to vasodilation, contraction of bronchioles, laryngeal oedema and circulatory collapse.
What is neurongenic shock?
Injury to nervous system leading to loss of sympathetic vascular tone. This causes severe vasodilation.
What happens in TSS?
S. aureus/pyogenes produce exotoxins that stimulate T cells. Massive cytokine release leading to vasodilation.
Component of bacterial cell wall released after cell lysis which causes harmful effects
Endotoxin
Classification of bacteria with an extra membrane beyond the cell wall
Gram negative
Acronysm denoting main agent responsible for cell injury during reperfusion
ROS
Reactive oxygen species. Ischaemic damage leads to generation of free radicals. In reperfusion, oxygen binds to these to form ROS which can damage cell membranes.
Causative agent and symptoms of Botulism
Clostridium botulinum. Double vision and dysphagia
Growth factor released by platelets
PDGF
Area of body likely to detect S. Aureus in a healthy individual
Nose
Area of body likely to detect coagulase negative staph in a healthy individual
Skin
