Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

HEM 302 > Normal Hemostasis > Flashcards

Normal Hemostasis Flashcards

1
Q

What is haemostasis?

A

Haemostasis is the mechanism that keeps blood in a fluid state.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the three categories of normal haemostasis?

A

Primary hemostasis, secondary hemostasis, and tertiary hemostasis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the five major components involved in haemostasis?

A

Blood vessels, blood platelets, coagulation factors, coagulation inhibitors, and fibrinolysis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are blood platelets?

A

Fragments of cytoplasm of megakaryocytes, non-nucleated.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Where are blood platelets produced?

A

Mainly by the bone marrow.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the normal platelet count range?

A

95-400 x 10^9/l.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the lifespan of a platelet?

A

About 7-10 days.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What percentage of platelets are typically trapped in the spleen?

A

About 1/3.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the dimensions of a platelet?

A

Measures about 3x0.5 μm.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the volume of a platelet?

A

About 7-11 fl.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the three types of storage granules in platelets?

A

Dense granules, alpha/specific granules, and lysosomes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What substances are contained in the specific granules of platelets?

A

Fibrinogen, Factor V, vWF, platelet-derived growth factor, fibronectin, β-thromboglobulin, heparin antagonist (PF-4), thrombospodin, other coagulation factors.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What substances are contained in the dense granules of platelets?

A

Nucleotides (ADP, ATP, 5-HT), calcium, serotonin.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What do lysosomes in platelets contain?

A

Catalase.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the main function of platelets?

A

Formation of haemostatic plugs in response to vascular injury.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What happens in the absence of platelets?

A

Spontaneous leakage of blood through vessel walls.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Define primary haemostasis.

A

Formation of the primary platelet plug involving platelets, the blood vessel wall, and von Willebrand factor.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the consequences of abnormalities in primary haemostasis?

A

Hemorrhage from mucosal surfaces, petechial or ecchymotic hemorrhages, prolonged bleeding after venipuncture or wounds.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How does the normal endothelium prevent hemostasis?

A

By providing a physical barrier and secreting products that inhibit platelets, including nitric oxide and prostaglandin I2 (prostacyclin).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the key steps involved in the formation of the primary platelet plug?

A

Platelet adhesion, platelet activation, and aggregation to form a platelet plug.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the first event in hemostasis?

A

Adhesion of platelets to exposed subendothelium.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How is platelet adhesion mediated in areas of high shear rate?

A

Mediated by vWF, which binds to gp Ib in the platelet membrane.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How is platelet adhesion mediated in areas of low shear rate?

A

Mediated by fibrinogen, binding to gp Ia/IIa.

24
Q

What occurs during platelet activation?

A

Platelets change shape, activate the collagen receptor, undergo the release reaction, synthesize and release TXA2 and PAF.

25
Q

What substances are synthesized and released by platelets during activation?

A

TXA2 and platelet activating factor (PAF).

26
Q

How is platelet aggregation mediated?

A

Primarily by fibrinogen, with vWF playing a secondary role.

27
Q

What stabilizes the primary platelet plug?

A

Formation of fibrin.

28
Q

What is platelet procoagulant activity?

A

Exposed membrane phospholipid (PF3) becomes available for tenase and prothrombinase reactions.

29
Q

What characterizes blood coagulation?

A

Sequential activation of a cascade of circulating precursors culminating in the generation of thrombin.

30
Q

What are the components involved in blood coagulation?

A

Circulating coagulation factors, cofactors (factors V and VIII), calcium, and platelets.

31
Q

What are the manifestations of defects in the coagulation cascade?

A

Bleeding into cavities (chest, joints) and subcutaneous hematomas.

32
Q

List the coagulation factors.

A

Fibrinogen (fibrin), prothrombin, tissue factor, labile factor, proconvertin, antihaemophylic factor, Christmas factor, Stuart power factor, plasma thromboplastin antecedent, Hageman factor, fibrin stabilizing factor.

33
Q

Describe the coagulation cascade.

A

Involves enzyme complexes: extrinsic tenase (VIIa, TF, PL, Ca2+→Xa), intrinsic tenase (IX, VIII, PL, Ca2+ →Xa), prothrombinase complex (Xa, Va, PL, Ca2+).

34
Q

What physiological mechanisms limit blood coagulation?

A

TFPI, antithrombin III, heparin cofactor II, C1 esterase inhibitor, protein C, protein S.

35
Q

What is TFPI and what does it inhibit?

A

TFPI inhibits Xa, VIIa, and TF.

36
Q

What is the role of antithrombin III?

A

Inhibits thrombin and is enhanced by heparin.

37
Q

What is the role of protein C?

A

Inhibits FVa and FVIIIa.

38
Q

How is protein C activated?

A

Thrombin binds to thrombomodulin, activating protein C.

39
Q

What is tertiary haemostasis?

A

Formation of plasmin for breakdown of the clot.

40
Q

Define fibrinolysis.

A

Dissolution of the fibrin clot.

41
Q

How does tissue plasminogen activator (tPA) function?

A

Binds to fibrin, ensuring fibrin generation is localized to the clot.

42
Q

What is the role of activated protein C (APC) in fibrinolysis?

A

Destroys plasma inhibitors of tPA.

43
Q

How does thrombin inhibit fibrinolysis?

A

By activating thrombin-activated fibrinolysis inhibitor (TAFI).

44
Q

What substances can plasmin digest?

A

Fibrinogen, fibrin, FV, FVIII.

45
Q

List some therapeutic fibrinolytic agents.

A

Recombinant tPA, urokinase, streptokinase.

46
Q

What inhibits plasmin?

A

Plasminogen activator inhibitor (PAI), alpha2 antiplasmin.

47
Q

What are the possible causes of defective haemostasis with abnormal bleeding?

A

Vascular disorder, thrombocytopenia, defective blood coagulation.

48
Q

What is the normal range for thrombin time?

A

14-16 seconds.

49
Q

What conditions can prolong thrombin time?

A

Dysfibrinogenaemias, FDPs, DIC, heparin therapy.

50
Q

What does APTT measure and what is its normal range?

A

Intrinsic pathway, 30-40 seconds.

51
Q

What conditions can prolong APTT?

A

Haemophilia.

52
Q

What does PT measure and what is its normal range?

A

Extrinsic pathway and common pathway, 10-14 seconds.

53
Q

What conditions can prolong PT?

A

Liver disease, warfarin therapy, DIC.

54
Q

What is the indication for a fibrinogen assay?

A

Fibrinogen deficiency, reduced in DIC.

55
Q

What is the normal range for bleeding time?

A

3-8 minutes.

56
Q

What does the platelet count test measure?

A

Number of platelets in the blood.

HEM 302 (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions