Blood Coagulation Flashcards

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1
Q

Blood coagulation define :

A

Process by which blood changes from a liquid to a gel, forming a blood clot

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2
Q

Heamostasis define

A

Process enables the cessation of bleeding in response to vascular injury
Prevents blood loss + enables tissue repair

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3
Q

Thrombosis define:

A

Blood clots are formed when they are not needed; limit/ block blood flow (normally in vein)
Blood clot=thrombus

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4
Q

Embolism define:

A

When a thrombus breaks loose and travels from one location in the body to another: blood clot=embolism

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5
Q

Haemostasis steps

A

Blood vessel injury

Primary haemostasis =vasoconstriction + platelet plug formation
Secondary haemostasis = stable clot formation : coagulation cascade activation
Fibrinolysis/tertiary haemostasis = vessel repair and dissolution of clot

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6
Q

Primary haemostasis what happens simplified:

A

Vasoconstriction- reduces blood flow therefore reduces blood loss
Platelet plug formation- involving platelet adhesion, activation, aggregation

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7
Q

Steps in platelet plug formation:

A

Platelet adhesion
Platelet activation
Platelet aggregation

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8
Q

Platelet life span:

A

7-10 days
150,000-400,000 platelets per micro litre of blood

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9
Q

Platelet plug formation: adhesion explain

A

Breach of endothelial cells = exposure of collagen
vWF (von Willebrand factor) binds to collagen
GPIb-V-IX binds to vWF immobilised on collagen
GPVI and GPIa/IIa (a2B1) binds to exposed collagen

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10
Q

Platelet plug formation: Activation

A

Platelets change shape
Release vWF,fibrinogen,ADP, TXA2
ADP( binds to P2Y12 receptors on platelets) and TXA2 bind to TXA2 receptors on platelets ; both activating GPIIb/IIIa

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11
Q

Platelet plug formation: aggregation

A

Activation of GPIIb/IIIa receptor

GPIIb/IIIa binds to fibrinogen
GPIIb/IIIa vWF
=Bridges between platelets / aggregation

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12
Q

Coagulation factors : what does a mean? X to Xa

A

X= inactive precursor
Xa= active

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13
Q

Secondary haemostasis simplified

A

Stable clot formation; coagulation cascade activation- end result is the activation of thrombin which :
- converts fibrinogen to fibrin
- induces more platelet recruitment and activation

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14
Q

Pathways in coagulation cascade

A

Extrinsic / Tissue factor pathway
Intrinsic / Contact pathway
Common pathway

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15
Q

coagulation cascade: Extrinsic / Tissue factor pathway what happens?

A

Activated by ‘extrinsic’ factors- exposure of endothelial TF following injury
III (Tissue factor) interacts with factor VII to activate= VIIIa to activate factor X to Xa = extrinsic tenase complex

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16
Q

factor VII to activate= VIIIa needs?

A

Vitamin K
And tissue factor (III) -when in blood

17
Q

coagulation cascade:Intrinsic/ Contact pathway what happens?

A

Activated by ‘intrinsic’ factors present in blood
Factor XII —> XIIa which activates factor XI to XIa which activates IX to IXa
Then intrinsic tenase complex

18
Q

Intrinsic tenase complex

A

Factor XIa activates IX (to IXa) which combines with VIIa to activate Factor X —> Xa

19
Q

Extrinsic tease complex

A

III (Tissue factor) interacts with factor VII to activate= VIIIa to activate factor X to Xa

20
Q

Prothrombinase complex

A

Factor Xa , Va and Calcium bind together

21
Q

Prothrombinase complex activates?

A

Prothrombin (factor II ) into thrombin (factor IIa)

22
Q

coagulation cascade:Common pathway what happens?

A

May result after the activation of factor X at the end of either pathway.
Prothrombinase complex formed = activates prothrombin (factor II) into thrombin (factor IIa).
Thrombin (IIa) activates factor I (fibrinogen) to Ia (fibrin). Which binds to XIIIa to form cross-linked fibres

23
Q

Factor IIa (thrombin) can also bind to? (Despite factor I)

A

PPAR receptor on platelets —> platelet activation/aggregation

24
Q

Important brakes on the coagulation cascade

A

Look notes

25
Q

Fibrinolysis

A

To break down fibrin

26
Q

Tertiary haemostasis

A

Fibrinolysis
Thrombolysis
Tissue plasminogen Activator factor (t-PA) -PRODUCED BY ENDOTHELIAL CELLS
Convert plasminogen to plasmin
Factor Ia(fibrin) converted to fibrin degradation products

27
Q

Haemostatic balance

A

Equilibrium between pro-coagulant/pro-thrombothic and anticoagulant /anti- thrombothic factors

28
Q

Pro-thrombin factors and anti-thrombotic factors

A

Pro-thrombin factors: increase in coagulation, platelets or decrease in Fibrinolysis

anti-thrombotic factors: decrease in coagulation, platelets or increase in Fibrinolysis

29
Q

Haemostasis disbalance when there is more anti-thrombotic factors leads to?

A

Bleeding

30
Q

Haemostasis disbalance when there is more pro-thrombotic factors leads to?

A

Thrombosis

31
Q

Arterial thrombus vs venous thrombus

A

Arterial thrombus- white; large platelet component

Venous thrombus- red; large fibrin component and rbcS

32
Q

Factors contributing to thrombosis

A

Described in Virchow’s triad
Hypercoagulability + vascular damage + circulatory stasis

If you have all 3= high risk at developing a thrombus

33
Q

What serious medical problems caused by clots?

A

Venous thromboembolism (VTE)
-deep vein thrombosis
-pulmonary embolism
Heart attack from atherosclerosis
Stroke from atrial fibrillation