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Flashcards in Hematology - Physiology Deck (56)
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1
Q

What is the blood group of an individual with the A antigen on red blood cells and B antibody in plasma?

A

Group A

2
Q

What is the blood group of an individual with the B antigen on red blood cells and A antibody in plasma?

A

Group B

3
Q

What is the blood group of an individual with both A and B antigens on red blood cells?

A

Group AB (universal recipient)

4
Q

What is the blood group of an individual with neither A nor B antigens on red blood cells and both A and B antibodies in plasma?

A

Group O (universal donor)

5
Q

What is the blood type of an individual who is a universal recipient of blood cells?

A

Blood group AB; A and B antigen on red blood cells

6
Q

What is the blood type of an individual who is a universal donor of blood products?

A

Blood group O; neither A nor B antigens on red blood cells

7
Q

A patient receiving a blood transfusion suddenly develops symptoms of anaphylaxis, renal failure, and hypotension and has schistocytes on a smear; what is the likely cause?

A

Incompatible blood type transfusion

8
Q

What happens when an Rh-negative mother is exposed to Rh-positive blood (for instance, during delivery)?

A

Exposure to Rh-positive blood (which has the Rho antigen) will result in the development of anti-Rh immunoglobulin G antibodies, which may complicate future pregnancies

9
Q

Which class of antibodies are produced against the ABO blood groups?

A

Immunoglobulin M

10
Q

Which class of antibodies are produced against Rh factor?

A

Immunoglobulin G

11
Q

If a mother is blood type O and her fetus is blood type B, will the fetus be at risk for hemolytic disease of the newborn?

A

No; antibodies against ABO blood groups are immunoglobulin M class and do not cross the placenta

12
Q

What happens when an Rh-negative mother with anti-Rh antibodies becomes pregnant with a child who is Rh positive?

A

Erythoblastosis fetalis; the anti-Rh immunoglobulin G crosses the placenta and causes hemolysis in the newborn

13
Q

What part of the fibrinolytic system also activates the complement cascade by cleaving C3 to C3a?

A

Plasmin

14
Q

Kallikrein links the coagulation cascade to the kinin cascade through its activation of _____ and to the fibrinolytic system through its activation of _____.

A

Bradykinin; plasminogen (to plasmin)

15
Q

Name two reactions initiated by high-molecular-weight kininogen.

A

High-molecular-weight kininogen is the initial reagent in the kinin cascade and stimulates the coagulation cascade by interacting with factor XII

16
Q

What does plasmin create when it interacts with fibrin clots?

A

Fibrin split products (fibrin degradation)

17
Q

Once high-molecular-weight kininogen cleaves to form bradykinin, what are the effects of the kinin cascade?

A

Vasodilation, vascular permeability, and pain

18
Q

What factor converts prokallikrein to kallikrein and factor XI to XIa?

A

Factor XIIa; it is thus involved in both the kinin cascade and the coagulation cascade

19
Q

Which coagulation factors are specific to the intrinsic coagulation pathway?

A

Factor XII, factor XI, factor IX, and factor VIII

20
Q

Which coagulation factors are specific to the extrinsic coagulation pathway?

A

Factor VII and tissue factor (thromboplastin)

21
Q

Which coagulation factors are common to both the intrinsic and extrinsic coagulation pathways?

A

Factor X, factor V, factor II (prothrombin), and factor XIII

22
Q

What is the end result of the coagulation cascade?

A

The conversion of fibrinogen into fibrin to form a fibrin mesh that will stabilize the platelet plug

23
Q

Which reactions in the coagulation cascade require calcium and a phospholipid surface as cofactors?

A

The conversion of factor IX to IXa, VII to VIIa, X to Xa, and II to IIa

24
Q

What are two stimuli for the conversion of factor X to factor Xa?

A

Activated factor VIIa, or factor IXa with factor VIIIa as a cofactor; this is where the intrinsic and extrinsic pathways converge

25
Q

Which four reactions is thrombin involved in?

A

Thrombin (IIa) cleaves fibrinogen into fibrin monomers, activates factor XIII to help stabilize and cross-link the fibrin mesh, and activates both factor VIII and factor V

26
Q

What ion does factor XIII require to stabilize the fibrin mesh?

A

Calcium

27
Q

Why do susceptible individuals develop angioedema when taking an angiotensin-converting enzyme inhibitor?

A

Angiotensin-converting enzyme deactivates bradykinin; blocking this results in the unopposed activation of bradykinin by kallikrein

28
Q

Name two initiators of the intrinsic coagulation pathway.

A

Factor XII is converted to XIIa in the presence of endothelial damage (collagen basement membrane and activated platelets) and by high-molecular-weight kininogen

29
Q

What disorder results from a deficiency of factor VIII?

A

Hemophilia A

30
Q

What disorder results from a deficiency of factor IX?

A

Hemophilia B

31
Q

A patient is severely deficient in vitamin K; which coagulation factors will be affected?

A

This will result in decreased levels of factors II, VII, IX, X, and proteins C and S

32
Q

What reaction accounts for the effects of heparin?

A

Heparin activates antithrombin, resulting in inhibition of thrombin and factors IXa, Xa, XIa, and XIIa

33
Q

Name four mediators of thrombus formation or degradation that are found within the vascular endothelial cell.

A

von Willebrand's factor, thromboplastin, tissue plasminogen activator, and prostaglandin I2

34
Q

Which molecule, found on the surface of vascular endothelial cells, is a cofactor in the activation of protein C, an anticoagulant?

A

Thrombomodulin, which is located on the surface of vascular endothelial cells

35
Q

Which molecule binds the subendothelial collagen that is exposed after endothelial damage?

A

von Willebrand's factor binds to the subendothelial collagen and attaches to activated platelets

36
Q

Via which molecule does von Willebrand's factor attach to platelets?

A

von Willebrand's factor binds to glycoprotein Ib, found on the platelet surface membrane

37
Q

What event causes expression of glycoprotein IIa/IIIb on the platelet membrane?

A

Upon adenosine diphosphate activation of the platelet, glycoprotein IIa/IIIb is inserted into the surface membrane

38
Q

How do platelets adhere to one another?

A

Glycoprotein IIb/IIIa binds fibrinogen, bridging platelets together

39
Q

Which contributors to thrombogenesis are found within platelets?

A

von Willebrand's factor, fibrinogen, and, upon cyclooxygenase activation of the arachidonic acid cascade, thromboxane A2

40
Q

What is the difference between the function of glycoprotein Ib and glycoprotein IIb/IIIa on the platelet surface?

A

Glycoprotein Ib binds von Willebrand's factor on a damaged endothelial surface, whereas glycoprotein IIa/IIIb binds fibrinogen attached to other platelets

41
Q

What process occurs during the adhesion stage of platelet plug formation?

A

The platelet adheres to exposed subendothelial collagen via glycoprotein Ib and von Willebrand's factor

42
Q

Which product of the arachidonic acid pathway favors aggregation of platelets? Which molecules inhibit aggregation?

A

Thromboxane, which is released by platelets, is proaggregation; prostacyclin and nitric oxide, released by endothelial cells, are antiaggregation

43
Q

How does aspirin prevent clot formation?

A

Aspirin inhibits cyclooxygenase in the platelets, thereby preventing TxA2 formation and thus aggregation of platelets

44
Q

What occurs during the swelling stage of platelet plug formation?

A

The platelet plug swells as many platelets bind together secondary to adenosine diphosphate activation of glycoprotein IIa/IIIb bridge formation

45
Q

Which ion helps to strengthen the platelet plug once it has formed?

A

Calcium

46
Q

Which stage of platelet plug formation is affected by ticlopidine and clopidogrel?

A

Swelling; these drugs inhibit the adenosine diphosphate-induced expression of glycoprotein IIa/IIIb

47
Q

Which medication directly interferes with glycoprotein IIa/IIIb?

A

Abciximab

48
Q

What enzyme is involved in vitamin K activation?

A

Epoxide reductase

49
Q

How does warfarin act as an anticoagulant?

A

It inhibits epoxide reductase, thereby inhibiting the activation of vitamin K

50
Q

Why do neonates receive an injection of vitamin K soon after birth?

A

Neonates lack enteric bacteria that produce vitamin K and can therefore be deficient in the vitamin K-dependent factors and suffer hemorrhagic disease

51
Q

Name three endogenous factors that initiate anticoagulation.

A

Antithrombin III, protein C, plasminogen

52
Q

What is the role of protein S in anticoagulation?

A

Protein S is a cofactor for protein C activation, which inactivates factors Va and VIIIa

53
Q

How does plasminogen act as an anticoagulant?

A

Plasminogen is activated by tissue plasminogen activator to plasmin, which cleaves the fibrin clot

54
Q

What is tissue plasminogen activator used for clinically?

A

As a thrombolytic in cases of acute stroke or myocardial infarction within hours of clot formation; tissue plasminogen activator activates plasminogen to plasmin

55
Q

What is the result of the factor V Leiden mutation?

A

The mutation results in a factor V that resists inactivation by activated protein C, leading to a hypercoagulable state

56
Q

What is the relationship between von Willebrand's factor and factor VIII?

A

von Willebrand's factor prolongs the half-life of factor VIII, which is why there is an increase in partial thromboplastin time in severe variants of von Willebrand's disease