Vascular system pathology Flashcards
What factors favor fluid retention in the interstitium and body cavities?
- Low hydrostatic pressure
- Osmotic pressure
What factors retain fluid within circulation?
- Higher oncotic pressure in plasma due to ions & proteins
- The selective permeability of the endothelium which can open to allow fluid & ions through
What is exudate (inflammatory) oedema classified as?
Serous, fibrinous and suppurative
How does oedema form when there is a imbalence on fluid retaining factors?
- decreased plasma osmotic pressure
- Increase in capillary permeability, hydrostatic pressure and in osmotic pressure of interstitium (salt retention)
How does a lymphatic blockage cause vessel damage?
- vessel damage or scarring with fibrosis
- nodule pathology (tumour, hyperplastic inflammatory response))
What can lead to increased caillary hydrostatic pressure in terms of blood stagnation?
Increased capillary hydrostatic pressure caused by increased venous pressure from heart disease or with decreasing venous outflow
What are the different ways oedema could present?
- Ascites (fluid filling abdomen).
- Hydrothorax
- Subcutaneous oedema
What is hyperaemia?
increase inflow of blood causing erythema and acute inflammation
What is localised venous congestion?
- e.g intestinal torsion
- vessel compression occludes veins but blood still enters via arteries
- venous blood accumulates in capillaries and veins
- Hypoxic necrosis of tissue
What is generalised venous congestion?
- obstruction of blood flow due to decreased heart function
- blood retains behind obstruction
What tissue is affected if there is congestion on the left side of the heart?
pulmonary circulation congestion
What tissue is affected if there is congestion on the right side of the heart?
hepatic circulation congestion
What does generalised congestionin the lungs?
- Diffuse reddening
- Darkening due to the process of hypostatic congestion
- Oedema
What is the appearnace of congestion in the liver?
In liver there is a nutmeg appearance and there is a congestion around the central veins
How does a haemorrhage present in the GIT or UT?
-inflammaiton or ulcers
-haematemesis
-melena
-dysentry
What is insidious haemorrhage?
-damage to endothelium
-coagulopathy
what are the types of coagulopathies?
-haemophilia
-anticoagulants
-consumption coagulopathies
What is Thrombocytopenia?
platlet deficiency in the blood
What is Septicaemia?
blood poisoning - large amount of bacteria entering blood stream
How can clotting be restricted?
avoid coagulation of the entire vascular tree
-thrombomodulin converts thrombin to anticoag enzyme
-plasmin cleaves fibrin
What are causes of hypercoagulability?
-increased number of platelets
-increased fibrin, clotting factors
-decreased activity of fibrinolysis
What are thhe different fates of a thrombus?
- dissolution (fibrinolysis)
2.vessel obstruction (fibrosis) - organisation and recanilisation
- embolisation- fragment breaks away
What are the different types of embolism’s?
-from thrombi-thromboembolism
-fat
-fibrocartilagenous
-tumour cells
-parasites
-bacterial/infectious/septic
-gas/air
Where do arterial emboli lodge?
downstream at bifurcation sites
Where do venous emboli lodge?
pulmonary circulatiopn
What is a saddle thromboembolus?
-in distal aorta where bifurcates to form iliac arteries
-thrombi form and more or less occlude iliac artery
-signs of pain and coldness in hindfeet
Where can fat emboli come from?
fragments of fat from medullary cavity after fracture
Where can fibrocartilaginous emboli come from?
-from degenerate intervertebral disc, dogs
-ruptured
-material get into vessels and vertebral canal and travel to lungs
What are malignant tumour emboli?
-rafts of tumour cells
-may establish as secondary tumour-metastasis
What are parasitic emboli?
-infrequent
-vessel with profiles of one or more parasites within
-inside thrombus
What are bacterial emboli?
-septicemia or bacteriaemia
-bacterial colonies lodge in capillaries
What does the outcome of the embolism depend on?
-extent of occlusion
-nature of embolus
-site-tissue vunerability and embolus moves
-brain, heart, kidney affected by short period of anaxia
What does a occusion at end of artery cause?
ischaemic necrosis
What are common causes of ischemia?
-thrombosis
-embolism
-compression
-vasoconstriction
-vasculitis
What are the effects of infarction dependent on?
-sensitivity to hypoxia
-local circulation
-duration of ischaemia
What is shock?
state of generalised tissue hypoperfusion
caused by decrease effective circulating blood volume and/or decreased peripheral vascular resistance
What is hypovolaemic shock?
-Blood/fluid loss–> reduced circulating bolume
-Haemorrhage, diarrhoea or severe bones
-10% decrease in blood vol- no fall in BP
>35% loss of vol, BP falls significatnyl, tissue perfusion inadequate
What is cardiogenic shock?
-Cardiac dysfunction
-Infarction, area of anoxia to myocardium or serious cardiac arrythias
-Compensatory mechanisms (symp NS)
But, if unsuccessful–> stagnation of blood
What is blood maldistribution?
-Increased peripheral vascular diameter
-Created blood pooling/stagnation
-Anaphylaxis, neurogenic, septic
what is disseminated intravascular coagulation?
A coagulopathy in which clotting and anticlotting mechanisms occur at the same time
what are the steps in disseminated intravascular coagulation
- TF release and platelet aggregation
- widespread thrombosis
- activation of fibrinolysis/inhibition of thormbin, platelet activation and fibrin formation OR widespread vascular occlusion
- lysis of thrombi and consumption of clotting factors OR widespread ischaemia
- widepread haemorrages (or widepread ischaemia)
