ic3 Flashcards
(55 cards)
thrombosis
process in which thrombus forms
thrombus
intravascular mass formed during life from constituents of blood (blood clot)
predisposing factors for thrombosis
1) injury to endothelium
2) alteration in blood coagulability
3) alteration in blood flow
venous thrombosis
stasis -> build up of activated clotting factors -> thrombus formation
deep vein thrombosis
common clinical states for thrombosis
1) atrial fibrillation: desynchronised, irregular, ineffective beating of atrium in form of cardiac arrhythmia (irregular heartbeat) -> pockets of stasis in atrium -> increased possibility of thrombus formation -> spread to other parts of body -> cerebral infarction -> stroke
2) prosthetic cardiac valves
3) major surgeries (post op/post-partum state)
4) prolonged bed rest/immobilisation (deep veins in legs/pelvis)
5) disseminated cancer (cancer cells produce procoagulant substances -> inappropriate thrombosis)
6) oral contraceptive (increased oestrogen)
clinical significance of thrombosis
thrombus in veins -> local vascular occlusion (venous congestion, swelling, pain in affected lower limb) -> embolisation -> vascular occlusion elsewhere
thrombus in arteries -> arterial occlusion -> decreased blood flow to affected organ (ischaemia), cerebral artery -> brain necrosis, coronary artery -> myocardial necrosis, renal artery -> renal necrosis
fate of thrombus
1) ideal: resolution/lysis: broken down naturally by body natural fibrinolysis mechanisms/aid of drugs
2) propagation: thrombus enlarge, partial occlusion become more complete occlusion -> > serious outcomes
3) organisation & recanalisation: new blood vessels form, restore some degree of blood vessel formation
4) embolism: thrombus dislodged, travel to other parts of circulation, occlude elsewhere
embolism
process where embolus is carried by blood to site distant from point of origin
embolism
process where embolus is carried by blood to site distant from point of origin
embolus: detached intravascular solid/liquid/gaseous material
type of emboli
1) solid (e.g. detached thrombus, tissue fragments, tumour clumps, foreign body)
2) liquid (e.g. fat lobules, amniotic fluid)
3) gaseous (e.g. air, nitrogen)
4) septic (infected blood clot, e.g. fungi, bacteria)
effects of embolism
1) vascular occlusion (necrosis of target organs, death)
2) septic emboli (infection)
3) tumour dissemination (cancer)
pulmonary (thrombo) embolism
comes from venous thrombosis (deep veins of legs/pelvis)
effects: sudden death (acute right heart failure), pulmonary necrosis
special types of embolism
1) fat (fat from bone marrow released during fracture)
2) air (DCI)
3) amniotic fluid
infarction
necrosis due to ischaemia (usually occlusion of artery, sometimes occlusion of venous drainage)
types of infarcts: white infarct (non-haemorrhagic), red infarct (haemorrhagic)
arterial occlusion -> renal infarct, venous occlusion -> testicular torsion
effects of ischaemia
1) remains viable/compensated by overlapping blood supply
2) infarction
3) healing by fibrosis
4) ischaemic atrophy
inflammation
first local response to injury
acute and chronic differentiated by duration, type of inflammatory cells
not all inflammation caused by infection, these type treated by anti-inflammatory/immunosuppressive meds/antibiotics
signs of inflammation
warmth (calor) (vasodilation)
redness (rubour) (vasodilation)
swelling (tumour) (oedema)
painful (dolor) (stimulation of nerve ending/medications that cause pain)
loss of function (functio laesa) (tissue damage/voluntary lack of use)
physiological response in acute inflammation
1) vascular response/changes
. increase blood flow (vasodilation)
. increase vascular permeability (loss of endothelial cell integrity, leakage of fluids/plasma proteins, transudate -> exudate)
. increase endothelial cell permeability (expression of adhesion molecules, production of chemokines)
2) cellular response: recruitment of leukocytes
. accumulation of leukocytes at injury site
benefits of vasodilation and oedema
1) improve supply of oxygen and nutrients
2) dilution of harmful chemicals/toxins
3) ‘deliver antigens’ to draining lymph nodes
4) facilitate emigration of leukocytes
5) bring in vital plasma proteins (fibrinogen, complement, antibodies, mannose-binding lectins), induce lysis, acts as opsonins (enhance phagocytosis)
leukocyte recruitment
1) adhesion to endothelial cells (produce chemokines to attract WBC)
2) diapedesis (transmigration of WBC, squeeze between gaps of blood vessel into tissue space)
3) chemotaxis (other WBC & cells produce chemicals that attract WBC)
primary effector cells during early phase of inflammation
macrophages, neutrophils
main functions of macrophages
1) phagocytosis of bacteria
2) production of inflammatory mediators
3) synthesis of molecules affecting antiviral defences
4) initiation of immune response
5) clean up (scavenging)
6) fever, acute phase reaction, cachexia
properties of chemical mediators of inflammation
1) cell derived (produced locally)/plasma
2) stored/easily generated
3) liable (short-lasting effects)
4) localised effects
5) bind to receptors of target cell
6) similar/opposing effects (control mechanism)
functions of chemical mediators of inflammation
1) vasodilation/vascular permeability
2) leukocyte recruitment & stimulation
3) systemic effects