Hemostasis and Coagulation

Question 1

Aspirin function

Answer 1

Inhibits platelet thromboxane (TXA2) formation
-Irreversible inhibitor of cyclooxygenase (COX)
-Decreases TXA2: PGI2 ratio

Question 2

Heparin

Answer 2

Activates antithrombin III and inactivates thrombin

Question 3

Warfarin (oral anticoagulant)

Answer 3

Blocks vitamin K epoxide reductase (VKOR) in liver and prevents regeneration of the active form of vitamin K
-Inhibits synthesis of mature vitamin K dependent clotting factors

Question 4

Streptokinase/Urokinase

Answer 4

Thrombolytic agent; plasminogen activator
-Converts plasminogen to plasmin enabling dissolution of clots

Question 5

Tissue Plasminogen activator

Answer 5

Used to dissolve a thrombus
-Converts plasminogen to plasmin enabling dissolution of clots.

Question 6

Test to detect the von Willebrand disease

Answer 6

Ristocetin cofactor assay which determines reduced platelet aggregation in von Willebrand disease

Question 7

Test to determine which type of platelet glycoprotein disease

Answer 7

Flow cytometry to distinguish Bernard-Soulier syndrome vs. Glanzmann thrombasthenia

Question 8

Disorders of the clotting pathway (coagulation cascade) include:

Answer 8

1) Hemophilia A and B
2) Vitamin K deficiency

Question 9

Disorders caused by defects in platelet plug formation:

Answer 9

1) Von Willebrand disease
2) Platelet defects: Thrombocytopenia, Bernard-Soulier syndrome, Glanzmann thrombasthenia

Question 10

Tests for primary hemostasis/platelet plug formation:

Answer 10

Bleeding time
Platelet count
vWF levels
Platelet aggregation studies (ADP, thrombin, ristocetin)
Flow Cytometry

Question 11

Tests for secondary hemostasis/clotting cascade:

Answer 11

Prothombin time (PT/INR)
APTT

Question 12

Function of Endothelial PGI2 (prostacyclin) and nitric oxide:

Answer 12

Prevent platelet aggregation

Question 13

Function of PGI2:

Answer 13

Increases platelet cAMP levels and inhibits activation (Thromboxane antagonist)

Question 14

Function of Antithrombin III

Answer 14

-Inactivates thrombin and factor Xa and prevents clotting

Question 15

Which molecule activates Antithrombin-III?

Answer 15

Heparin (glycosaminoglycan)

Question 16

Which vitamin is Protein C and S dependent on?

Answer 16

Vitamin K

Question 17

What activates protein C and protein S?

Answer 17

Binding of thrombomodulin to thrombin

Question 18

Function of proteins C and S

Answer 18

Inactivation of Va and VIIIa of the coagulation cascade

Question 19

Elevated levels of what indicates a high risk for pulmonary embolism?

Answer 19

Highly elevated D-dimer levels

Question 20

Primary hemostasis

Answer 20

Platelet plug formation

Question 21

Secondary hemostasis

Answer 21

Blood coagulation

Question 22

Steps in Hemostasis

Answer 22

1. Vascular spasm/vasoconstriction
2. Platelet plug formation/primary hemostasis
3. Blood coagulation/secondary hemostasis
4. Clot stabilization and resorption

Question 23

Defect is which protein causes Bernard-Soulier syndrome?

Answer 23

Platelet receptor Gp1b: this binds collagen which allows adhesion of von Willebrand factor biding to allow for adhesion to the subendothelial collagen layer

Question 24

Factor [ ] levels are low in hemophilia A

Answer 24

Factor VIII

Question 25

Factor [ ] levels are low in hemophilia B

Answer 25

Factor IX

Question 26

Disease characterized by: instability of Factor VIII -Increased mucosal bleeding -Easy bruising -Epistaxis -Increased post-operative bleeding -Prolonged bleeding following tooth extraction

Answer 26

von Willebrand Disease

Question 27

Abnormal lab findings in von Willebrand Disease

Answer 27

1. Primary hemostasis: prolonged bleeding time, abnormal Ristocetin assay 2. Secondary hemostasis: prolonged APTT

Question 28

Features of Thrombocytopenia

Answer 28

Increased bleeding time and low platelet count

Question 29

Disease that is due to GpIIb/IIIa defect

Answer 29

Glanzmann Thrombasthenia

Question 30

EDTA (in-vitro)

Answer 30

Calcium chelator

Question 31

Warfarin (Coumadin)

Answer 31

Inhibits gamma-carboxylation of vitamin K dependent clotting factors; Inhibits regeneration of vitamin K; inhibits vitamin K epoxide reductase

Question 32

Erythropoietin (EPO)

Answer 32

Produced by the kidneys to increase erythrocyte precursors.

Question 33

Thrombopoietin (TPO)

Answer 33

Hormone from liver stimulates thrombocyte formation

Question 34

Cytokines

Answer 34

Local hormones of bone marrow

Question 35

Which factors stimulate leukocyte production?

Answer 35

Colony-stimulating factor (CSF) and interleukin

Question 36

Life span of Erythrocytes

Answer 36

120 days (removed by spleen macrophages)

Question 37

Individuals that express N-acetylgalactosamine transferase have which blood group?

Answer 37

A

Question 38

Individuals that express galactose transferase have which blood group?

Answer 38

B

Question 39

For individuals that express the necessary enzymes within the blood have which blood group?

Answer 39

O

Question 40

What is the main stimulus for erythropoiesis?

Answer 40

Hypoxia

Question 41

Poikilocytosis

Answer 41

The presence of poikilocytes in the blood: RBCs of distorted shape -Various shapes can be due to membrane abnormalities or due to traumatic conditions

Question 42

Anisocytosis

Answer 42

Blood abnormality where the RBCs are of unequal sizes -Can be detected in peripheral smears -Can signify conditions such as anemia and thalassemia

Question 43

Hereditary spherocytosis

Answer 43

Caused by molecular defects in genes that code for spectrin, ankyrin, band 3 and band 4 proteins. This results in a spherical shape of RBC than the biconcave nature of it.

Question 44

The shape of RBCs in patients with beta-Thalassemia:

Answer 44

Target cells

Question 45

Beta-thalassemia

Answer 45

Indicates decreased or absent beta chains. Hereditary hypochromic anemia

Question 46

Sickle cell anemia

Answer 46

Genetic defect in hemoglobin molecule (Hb-S) where a single point mutation causes hydrophobic glutamic acid replaced by hydrophobic valine at point 6 in the beta chain

Question 47

T cells

Answer 47

Cell mediated immunity: differentiate in the thymus -Long life span -Attack viruses, fungi, transplanted organs, cancer cells and some bacteria

Question 48

B cells

Answer 48

First recognized in the bone marrow: -Production of antibodies -Destroy bacteria and their toxins -Turn into plasma cells that produces antibodies -Variable life span

Question 49

Natural killer cells (NK): programmed during development

Answer 49

-Attack many different microbes and some tumor cells -Destroy foreign invaders by direct attack

Question 50

Redness following injury site such as wound or cut is due to:

Answer 50

Hyperemia: increased diameter of vessels at the site

Question 51

Pain following inflammation of injury site is due to:

Answer 51

The release of bradykinin and PGE2

Question 52

Which mediators of acute inflammation cause vasodilation?

Answer 52

Prostaglandins, nitric oxide, histamine

Question 53

Which mediators of acute inflammation cause increased vascular permeability?

Answer 53

Histamine, serotonin, bradykinin, leukotrienes

Question 54

Which mediators of acute inflammation cause fever?

Answer 54

Cytokines (IL-1, TNF), prostaglandins

Question 55

What increases the production of free radicals (Reactive oxygen species)?

Answer 55

Oxidant drugs (Sulfa drugs/Primaquine) or infection or fava beans -Defect in the pentose phosphate pathway leads to the accumulation of hydrogen peroxide accumulation that damage RBC membrane that leads to hemolysis

Question 56

G6PD deficiency results in the formation of:

Answer 56

Heinz bodies (denatured insoluble proteins) due to the inappropriate disulfide bond formation