haemostasis, haemorrhage & shock Flashcards
(19 cards)
what is haemorrhage?
excessive blood loss
what is shock?
decreased blood volume resulting in a fall in bp and impaired delivery of nutrients to cells
what are the general physiological responses to blood loss?
immediate stop the bleeding short term restore bp medium term restore fluid volume long term replace blood constituents
what are the components of immediate response?
vascular response
platelet response
plasma response
what is the vascular response?
SM spasm due to trauma myogenic response humoral factors(vasoconstrictors) Endothelium platelet adhesion & aggregation anticlotting and fibrinolysis
what is the platelet response?
damage to bv->turbulent blood flow -> platelets come in contact with vessel wall
platelets adhere (aggregate)
+ feedback- release chemicals to further aggregate
formation of platelet plug
seals small bv
what is the plasma response? (coagulation)
proteins & tissue components combine to convert fibrinogen-> fibrin to form clot
numerous clotting factors, many made in liver
synthesis required vit. K
clotting factors activated in enxyme cascade
one factor activated next
what is the difference between coagulation extrinsic and intrinsic pathway?
extrinsic=initiating clotting after injury
intrinsic=maintain process once started
what is fibrinolysis?
blood clot dissolves once served purpose
plasmin enzyme
what is the short term response?
blood pressure-loss of blood vol. fall in pressure compensatory mechanisms triggered by arterial baroreceptors- mediated by sympathetic nerves & hormones: adrenaline angiotensin II vasopressin (ADH)
what are medium term responses?
restore blood vol. by
shifting interstitial fluid back into bv
decreasing fluid loss in kidney
increasing fluid intake
what does arterial blood pressure cause? (due to varoreceptor reflexes)
vasoconstriction of arterioles -increased total peripheral resistance -decreased capillary bp decreases hydrostatic pressure pushing fluid out of capillary more fluid drawn in by oncotic pressure
what decreases fluid loss in kidneys?
decreased glomerular filtration
raised reabsorption of Na+ and water by stimulating release of vasoconstrictors:
renin-angiotensin-aldosterone
ADH
what is thirst?
a desire to drink hypothalamus is important control area stimuli include: raised plasma osmolarity low ECF vol. angiotensin II promotes dry mouth stretch receptors in stomach supress
what are long term responses?
restore plasma proteins -released from liver replace blood cells esp. RBC erythropoiesis -reg by erythropoietin -EPO released from kidney -stimulated RBC prod. in bone marrow -return to normal 2-3 months
what is shock?
inadequate blood flow to tissues associated with: -low cardiac output -low blood/ECF vol. reversible/irreversible irreversible=fatal
what is hypovolaemic shock?
low ECF vol. due to haemorrhage, sweating, diarrhoea, burns etc.
what is low resistance shock?
low peripheral resistance due to widespread vasodilation eg anaphylactic shock
what is cardiogenic shock?
heart fails as a pump
