Blood and Haemodynamic Pathology Flashcards
What are the two types of edema?
Local and generalised
What are the mechanisms of edema?
Increased vascular permeability, increased capillary hydrostatic pressure (venous obstruction, CHF, gravity), decreased osmotic pressure (hypoproteinemia), lymphatic obstruction
What causes edema in CHF?
Humoral/neurohumoral mechanisms promote sodium and water reabsorption by kidneys and expansion of extra cellular fluid
Describe the Starling forces in CHF.
Abnormal, due to increased venous capillary pressure and decreased plasma oncotic pressure
What does fast vs. slow build up of fluid in CHF result in?
Fast= fluid in lungs, slow= leg edema
How can edema from CHF be treated?
Diuretics, vasodilators, angiotensin converting enzyme inhibitors
What is elephantiasis?
Type of lymphatic obstruction caused by filariasis worms which live in lymphatic system
Compare acute and chronic haemorrhage/blood loss.
Acute= 20% of blood volume lost (1L)
Chronic= blood loss over longer period, eg. peptic ulcer, menstrual bleeding
What are examples of haemorrhage in body cavity?
Hemothorax, hemopericardium, hemoperitoneum, hemarthrosis
What is hemarthrosis and what causes it?
Bleeding into joint spaces, caused by injury or Haemophilia A
What are examples of haemorrhage in tissue?
Petechia, purpura, ecchymoses, hematoma
What is petechia and what causes it?
1-2 mm haemorrhages in skin or mucous membranes, as a result of capillary defects - anomalies in platelets, bacterial sepsis
What is purpura and what causes it?
Haemorrhages in skin greater than 2mm diameter forming plate-like lesions, result from inflammation in small blood vessels (vasculitis) or platelet abnormalities
What is Henoch-Schonlein purpura?
Allergic purpura, hypersensitive vasculitis and inflammatory response in blood vessel, active IgA mediated disorder following infection
What is ecchymoses?
Larger extravasations of blood into tissue (greater than 1-2 cm in diameter) causing purple/red discolouration
Describe the ecchymoses cascade.
1. Blood vessels rupture
2. RBCs die and release haemoglobin
3. Macrophages degrade haemoglobin via phagocytosis
4. Discolouration of skin changes to gold brown due to degradation of haemoglobin by haemosiderin
What is a haematoma?
Large leakage from large blood vessels due to trauma
How is blood loss limited?
Platelet activation -> platelet adherence to endothelial layer & each other -> fibrinogen clot
Vasoconstriction -> epinephrine/norepinephrine, reduced blood flow
What is thrombosis?
Disrupted blood flow as a result of blood clot formation in uninjured vessels, adherent to vascular endothelium
What is Virchow's triad?
Three mechanisms predisposing to formation of thrombus: endothelial injury, abnormal/disrupted blood flow, hypercoagulability
What is endothelial injury?
Physical loss of endothelium (activation of clotting cascade), endothelial dysfunction (atherosclerosis, trauma, surgery, hypertension, etc.)
Describe abnormal/disrupted blood flow in thrombosis.
Blood flow altered through stasis or turbulence
Stasis prevents dilution of clotting factors
What is hypercoagulability?
Alteration in the coagulation pathways
Primary (genetic) or secondary (acquired)
Describe the morphology of thrombosis.
Size and shape depends on site of origin and cause, vocally attached to underlying vascular surface
Describe arterial/cardiac thrombi.
Begin at site of injury or turbulence and grow in retrograde direction
Describe venous thrombi.
Occur at site of stasis and grow in direction of blood flow, large amounts of RBCs
