(MD 1) Biochemistry > Hemostasis > Flashcards

Hemostasis Flashcards

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1
Q

Which plasma protein is primarily responsible for maintaining oncotic pressure in blood vessels?
A. Fibrinogen
B. Immunoglobulin G
C. Albumin
D. Von Willebrand factor

A

C. Albumin

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2
Q

A marked decrease in albumin concentration would most directly lead to:
A. Increased platelet aggregation
B. Edema due to altered water distribution
C. Impaired fibrinolysis
D. Increased thrombin activity

A

B. Edema due to altered water distribution

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3
Q

Plasma proteins involved in immune defense include:
A. Albumin and fibrinogen
B. Complement proteins and immunoglobulins
C. Transferrin and ceruloplasmin
D. Alpha-2 macroglobulin and antithrombin III

A

B. Complement proteins and immunoglobulins

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4
Q

The primary hemostatic plug is composed mainly of:
A. Cross-linked fibrin only
B. Aggregated platelets and fibrin
C. Red blood cells and platelets
D. Collagen and elastin

A

B. Aggregated platelets and fibrin

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5
Q

The secondary hemostatic plug differs from the primary plug because it:
A. Is composed solely of platelets
B. Contains cross-linked fibrin
C. Does not involve thrombin
D. Is independent of coagulation factors

A

B. Contains cross-linked fibrin

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6
Q

Platelets are best described as:
A. Nucleated fragments of endothelial cells
B. Non-nucleated cell fragments derived from megakaryocytes
C. Small lymphoid cells
D. Granulocytes involved in innate immunity

A

B. Non-nucleated cell fragments derived from megakaryocytes

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7
Q

Approximately how many platelets are produced from a single megakaryocyte?
A. 400
B. 1,000
C. 4,000
D. 10,000

A

C. 4,000

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8
Q

Megakaryocytes arise from:
A. Myeloid progenitor cells only
B. Hematopoietic stem cells
C. Endothelial precursor cells
D. Reticulocytes

A

B. Hematopoietic stem cells

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9
Q

Which of the following initiates platelet involvement in hemostasis?
A. Aggregation
B. Secretion
C. Adhesion
D. Fibrinolysis

A

C. Adhesion

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10
Q

Normal endothelial cells are thromboresistant primarily because they:
A. Express tissue factor
B. Are positively charged
C. Synthesize PGI₂ and nitric oxide
D. Activate factor XII

A

C. Synthesize PGI₂ and nitric oxide

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11
Q

Prostacyclin (PGI₂) synthesized by endothelial cells causes:
A. Vasoconstriction and platelet aggregation
B. Vasodilation and inhibition of platelet aggregation
C. Platelet degranulation
D. Activation of thrombin

A

B. Vasodilation and inhibition of platelet aggregation

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12
Q

Heparan sulfate on endothelial cells inhibits coagulation by:
A. Activating fibrinogen
B. Inactivating thrombin
C. Activating factor XIII
D. Inhibiting plasmin

A

B. Inactivating thrombin

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13
Q

The two major subendothelial components required for platelet adhesion are:
A. Elastin and laminin
B. Collagen and fibrin
C. Collagen and von Willebrand factor
D. Fibrinogen and thrombin

A

C. Collagen and von Willebrand factor

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14
Q

Von Willebrand factor is synthesized primarily by:
A. Platelets only
B. Hepatocytes
C. Endothelial cells
D. Megakaryocytes only

A

C. Endothelial cells

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15
Q

High-molecular-weight vWF is most effective at platelet binding and is found in:
A. Circulation
B. Platelet plasma membrane
C. Endothelium
D. Liver

A

C. Endothelium

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16
Q

vWF stabilizes which coagulation factor in circulation?
A. Factor IX
B. Factor X
C. Factor VIII
D. Factor V

A

C. Factor VIII

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17
Q

The initial platelet receptor that binds exposed collagen is:
A. GPIb
B. GPIIb/IIIa
C. GPIa
D. GPVI

A

C. GPIa

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18
Q

Binding of vWF to platelets occurs via:
A. GPIIb/IIIa
B. GPIb
C. GPIa
D. GPV

A

B. GPIb

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19
Q

Exposure of GPIIb/IIIa allows binding of:
A. Collagen only
B. ADP only
C. Fibrinogen and vWF
D. Calcium only

A

C. Fibrinogen and vWF

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20
Q

Activated platelets differ morphologically from non-activated platelets by:
A. Being flatter
B. Becoming spherical with pseudopods
C. Losing surface receptors
D. Decreasing surface area

A

B. Becoming spherical with pseudopods

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21
Q

ADP promotes platelet aggregation primarily by:
A. Inhibiting thrombin
B. Masking GPIIb/IIIa
C. Unmasking GPIIb/IIIa
D. Activating fibrinolysis

A

C. Unmasking GPIIb/IIIa

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22
Q

Which substance is found in electron-dense granules?
A. Fibrinogen
B. Von Willebrand factor
C. ADP
D. Platelet-derived growth factor

A

C. ADP

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23
Q

Alpha-granules contain all EXCEPT:
A. Fibrinogen
B. vWF
C. Calcium
D. Platelet-derived growth factor

A

C. Calcium

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24
Q

Lysosomal granules function mainly to:
A. Promote clot formation
B. Inhibit platelet aggregation
C. Store ADP
D. Bind fibrinogen

Study These Flashcards
A

B. Inhibit platelet aggregation

25
Fibrinogen consists of: A. Two alpha chains only B. Three identical chains C. Two sets of alpha, beta, and gamma chains D. Four polypeptide chains
C. Two sets of alpha, beta, and gamma chains
26
Thrombin converts fibrinogen to fibrin by: A. Phosphorylation B. Removing fibrinopeptides C. Adding carboxyl groups D. Cross-linking lysine residues
B. Removing fibrinopeptides
27
The “soft clot” is characterized by: A. Cross-linked fibrin B. Non–cross-linked fibrin polymers C. Absence of platelets D. Absence of thrombin
B. Non–cross-linked fibrin polymers
28
Most coagulation enzymes belong to which class? A. Metalloproteases B. Aspartate proteases C. Serine proteases D. Cysteine proteases
C. Serine proteases
29
Which of the following is NOT a serine protease? A. Factor IX B. Factor X C. Factor V D. Factor XI
C. Factor V
30
Tissue factor corresponds to: A. Factor II B. Factor III C. Factor IV D. Factor VIII
B. Factor III
31
Which factor does NOT require proteolytic activation? A. Factor VIII B. Factor V C. Factor III D. Factor XI
C. Factor III
32
Calcium is also known as: A. Factor III B. Factor IV C. Factor V D. Factor XIII
B. Factor IV
33
Factor XIII is unique because it is a: A. Serine protease B. Kinase C. Transglutaminase D. Carboxylase
C. Transglutaminase
34
The intrinsic pathway is initiated by exposure to: A. Tissue factor B. Collagen and negatively charged surfaces C. Thrombin D. Fibrin
B. Collagen and negatively charged surfaces
35
Which factor is first activated in the intrinsic pathway? A. Factor XI B. Factor IX C. Factor XII D. Factor X
C. Factor XII
36
The extrinsic pathway is characterized by: A. Slower clot formation B. Dependence on tissue factor C. Absence of factor VII D. Activation only in plasma
B. Dependence on tissue factor
37
The extrinsic pathway forms a clot in approximately: A. 2 seconds B. 5 seconds C. 12 seconds D. 1 minute
C. 12 seconds
38
The pathway responsible for sustaining coagulation is the: A. Extrinsic pathway B. Intrinsic pathway C. Common pathway D. Fibrinolytic pathway
B. Intrinsic pathway
39
Thrombin promotes its own formation by activating: A. Only factor I B. Factors V, VIII, XI, and VII C. Only factor XIII D. Protein C
B. Factors V, VIII, XI, and VII
40
The major substrate of thrombin is: A. Plasminogen B. Fibrin C. Fibrinogen D. Prothrombin
C. Fibrinogen
41
Vitamin K–dependent coagulation factors include: A. I, V, VIII, XIII B. II, VII, IX, X C. XI, XII, XIII D. III, IV, V
B. II, VII, IX, X
42
Vitamin K is required for: A. Phosphorylation of serine residues B. γ-carboxylation of glutamate residues C. Cleavage of fibrinogen D. Activation of plasmin
B. γ-carboxylation of glutamate residues
43
γ-Carboxyglutamate residues are essential for: A. Binding fibrin B. Calcium-mediated membrane binding C. Thrombin inhibition D. Platelet secretion
B. Calcium-mediated membrane binding
44
Warfarin acts by inhibiting: A. Vitamin K carboxylase B. Vitamin K epoxide reductase C. Thrombin directly D. Cyclooxygenase
B. Vitamin K epoxide reductase
45
Thrombin bound to thrombomodulin results in: A. Increased clot formation B. Activation of protein C C. Inhibition of fibrinolysis D. Increased platelet aggregation
B. Activation of protein C
46
Activated protein C inactivates: A. Factors II and X B. Factors Va and VIIIa C. Factors IXa and XIa D. Factors VIIa and X
B. Factors Va and VIIIa
47
Protein S functions by: A. Inhibiting thrombin B. Anchoring APC to platelet membranes C. Activating fibrinogen D. Degrading fibrin
B. Anchoring APC to platelet
48
Antithrombin III primarily inhibits: A. Plasmin B. Thrombin C. Protein C D. Factor VIIa
B. Thrombin
49
Heparin enhances ATIII activity by: A. Binding calcium B. Binding lysyl residues on ATIII C. Inhibiting vitamin K D. Activating fibrinolysis
B. Binding lysyl residues on ATIII
50
The ATIII–heparin complex does NOT inhibit: A. Factor Xa B. Factor IXa C. Factor XIa D. Factor VIIa
D. Factor VIIa
51
Plasmin is formed from plasminogen by: A. Thrombin B. Tissue plasminogen activator C. Factor XIIIa D. Antithrombin III
B. Tissue plasminogen activator
52
The plasminogen activator with highest fibrin affinity is: A. u-PA B. Streptokinase C. t-PA D. APC
C. t-PA
53
Plasmin is inhibited in plasma by: A. Alpha-2 antiplasmin B. Protein S C. Heparin D. vWF
A. Alpha-2 antiplasmin
54
Aspirin decreases platelet aggregation by inhibiting: A. ADP receptors B. COX-1 and COX-2 C. Thrombin D. Factor Xa
B. COX-1 and COX-2
55
Clopidogrel acts by: A. Inhibiting TXA₂ synthesis B. Reversibly blocking ADP receptors C. Irreversibly blocking ADP receptors D. Inhibiting fibrinogen
C. Irreversibly blocking ADP receptors
56
Bleeding time assesses: A. Intrinsic pathway B. Platelet function C. Extrinsic pathway D. Fibrinolysis
B. Platelet function
57
Prolonged PT suggests dysfunction in the: A. Intrinsic pathway B. Extrinsic pathway C. Fibrinolytic system D. Platelet adhesion
B. Extrinsic pathway
58
aPTT is prolonged in: A. Warfarin therapy only B. Vitamin K deficiency only C. Hemophilia D. Thrombocytosis
C. Hemophilia
(MD 1) Biochemistry
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