Haemodynamic disorders, Thromboembolic Disease and shock Flashcards
What are the four factors responsible for oedema?
Increase hypostatic pressure
Decrease osmotic pressure- lose proteins
Increase vascular permeability
Blockage of lymphatic flow
How can oedema occur and be classified into?
Regional- Tumour, volvulus in the intestine.
Systemic- Heart pressure, congestion, haemorrhage etc. CHD
What happens during acute hepatic congestion?
Distension of central veins and sinusoids. Resulting in centrilobular necrosis. https://s3.amazonaws.com/brainscape-prod/system/cm/173/340/820/a_image_thumb.png?1450629341
What can aetiological factors that can occur causing acute hepatic congestion and what can be an indicator of this?
Chronic RHS heart failure. This is also known as nutmeg liver. Breakdown of red blood cells, haemosiderin laden macrophages.
What can aetological factors can affect pulmonary oedema etc?
LHS heart failure.
Acute- engorged alveolar and focal- intra alveolar. Haemorrage by diapedesis-leukocyte extravasation.
Chronic- Septa thickening over a chronic amount of time. Heart failure cells within the alveoli can be a good indicator.
What diseases can affect hepatic congestion by a decrease in osmotic pressure?
Dogs- Copper chronic disease
Horse- Ragwort
Sheep- Liver fluke
How does Ragwort poisoning of horses occur?
Alkaloids intoxication. Causes megalocytosis, fibrosis and bile duct proliferation.
Causes antimitotic affects on the hepatocytes
Megalocytosis- mitotic inhibition with continued nucleoprotein synthesis, increase in the size of the nuclei.
Aflatoxins
What is the difference between haemorrhage and congestion?
Congestion- Intact blood vessels are distended with erythrocytes
Haemorrhage- Accumulation of extravasated erythryocytes
Why does haemorrhage occur and what are the two types?
Occurs because of abnormal function or integrity of one or more of the factors that influence haemostasis. The endothelium, platelets or coagulation factors.
The two types are:
Rhexis- traumatic or physical rupture of a vessel wall
Diapedesis-the escape of blood from vessels where it may be difficult to detect a disruption to the vessel wall.
What is the significance or consequence of haemorrhage?
Depends on the loss however can lead to hypovolaemia, reduced tissue perfusion, haemorrhagic hypovolaemic shock.
What are the causes of diapedesis?
Endothelial injury by endotoxins, infectious agents and chemicals.
Immune complexes (type III hypersens.)
Collagen disorder or defects
Decreased platelet numbers (thrombocytopaenia) or abnormal platelet function (thrombocytopathy)
Decreased concentration or function of coagulation factors
What would you call blood in the urine?
Two terms:
1. Haematuria- when centrifuged the colour of the urine will become clear as the RBC sediments seperate.
- Haemoglobinuria- The other will not
What is haemostasis?
Cessation of blood loss after disruption of a vessel wall. Involves the interaction of endothelial, platelets and coagulation factors. Activation of clotting factors culminates in thrombin generation and conversion of circulating fibrin into insoluble fibrin. Can lead to a THROMBIS
Can you illustrate a primary haemostasis?
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Can you illustrate a secondary haemostasis?
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Can you illustrate the thrombo-anti thrombotic events in secondary haemostasis?
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What is the coagulation cascade?
Amplifying series of enzymatic reactions where inactive proenzymes are converted to active forms (clotting factors).
The extrinsic pathway is most important pathways activated by TF when vascular damage has occured.
Culminating in thrombin formation adn generation of insoluble fibrin from fibrinogen.
Coagulation factors- plasma proteins produced mainly by the liver, some require vitamin K for function.
Name some anti coagulation factors?
Antithrombin III produced by the liver and endothelium, inhibits the activity of thrombin
Proteins C and S are vitamin K depedent proteins that inactive factors VA and VIIIa
Tissue factor pathway inhibitor produced by endothelium prevents activation of extrinsic coagulation cascade.
How does damaged endothelium become prothrombotic?
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What is virchow’s triad?
Its states the three things together can lead to a thrombosis:
- Endothelial injury
- Hypercoagulability
- Abnormal blood flow
What are the causes of endothelial damage?
- Immune mediated vasculitis
- Toxins- Endotoxins
- Local extensions of infection = hepatic abscess
- DIC
- Infectious agents
- Vitamin E/ Selinium deficiency