Hemostasis

Question 1

the physiological process by which bleeding is stopped

Answer 1

Hemostasis

Question 2

Hemostasis occurs in two stages

Answer 2

1) formation of a platelet plug

2) Reinforcement of the platelet plug with fibrin

Question 3

Platelet aggregation is initiated when platelets come in contact with ____________ on the exposed surface of the _____________ blood vessel

Answer 3

collagen; damaged

Question 4

in response to contact with collagen, _____________ adhere to the site of vessel injury.

Answer 4

platelets

Question 5

Adhesion initiates platelet ___________, which in turn leads to massive platelet ________________

Answer 5

activation; aggregation

Question 6

Platelet aggregation is a complex process that ends with formation of ____________ between ______________ receptors on adjacent platelets.

For these bridges to form however, what must happen?

Answer 6

fibrinogen bridges; GP IIb/IIIa

for these bridges to form the GP IIb/IIIa receptors must first undergo activation- that is, they must undergo a configurational change that allows them to bind with fibrinogen

Question 7

activation of GP IIb/IIIa receptors can be stimulated by multiple factors including …………….

what happens to GPIIb/IIIa as a result

Answer 7

thromboxane A2; thrombin; collagen; platelet activation factor; ADP

Under the influence of these factors, GP IIb/IIIa changes its shape, binds with fibrinogen and thereby causes aggregation

these factors are important because different medications will act on these factors to inhibit platelet aggregation and the formation of a platelet plug

Question 8

What is the importance of the GP IIb/IIIa receptors on the surface of platelets ?

Answer 8

There are 50-80 thousand of these receptors on platelets. They are important because their activation permits binding of fibrinogen, which causes aggregation by forming cross-links between platelets.

Question 9

The aggregated platelets constitute a plug that stops bleeding; however; this plug is ____________ and must be reinforced with ____________ if protection is to last.

Answer 9

unstable; fibrin

Question 10

defined as the production of fibrin

Answer 10

coagulation

Question 11

a threadlike protein that reinforces the platelet plug

Answer 11

fibrin

Question 12

Fibrin is produced by these two convergent pathways

Answer 12

Convergent (intrinsic pathway) and the tissue factor pathway (extrinsic pathway)

These two pathways converge at factor Xa, after which they employ the same final series of reactions

Question 13

Once the coagulation cascade is initiated it becomes self_____________ & self_________________–

Answer 13

self sustaining; self reinforcing

each reaction in the sequence amplifies the reaction that follows

Question 14

The tissue factor pathway is also known as the

Answer 14

extrinsic pathway

Question 15

the convergent pathway is also known as the

Answer 15

intrinsic pathway

Question 16

this coagulation pathway is turned on by trauma to the vascular wall, which triggers release of tissue factor, also known as tissue thromboplastin

Answer 16

Extrinsic pathway

Question 17

This coagulation pathway is turned on when blood makes contact with collagen that has been exposed as a result of trauma to a blood vessel wall

Answer 17

Intrinsic pathway

Question 18

Important to our understanding of anticoagulant drugs is the fact that four coagulation factors require vitamin K for their synthesis - which factors are these ?

Answer 18

factors VII, IX, X and II (prothrombin)

Question 19

To protect against widespread coagulation, the body must inactivate any clotting factors that stray from the site of vessel injury. Inactivation is accomplished with ______________

Answer 19

antithrombin- a protein that forms a complex with clotting factors and thereby inhibits their activity

Question 20

As healing of an injured vessel proceeds, removal of the clot is eventually necessary. The body accomplishes this with ____________, an enzyme that degrades the fibrin meshwork of the clot.

Answer 20

plasmin

Plasmin is produced through the activation of its precursor, plasminogen

Question 21

The ___________ drugs act by promoting conversion of plasminogen into plasmin

Answer 21

fibrinolytic

Question 22

a ___________ is a blood clot formed within a blood vessel or within the heart

Answer 22

thrombus

Thrombosis (thrombus formation) reflects pathologic functioning of hemostatic mechanisms

Question 23

the_____________- drugs are most effective at preventing arterial thrombosis whereas _____________ are most effective against venous thrombosis

Answer 23

antiplatelet; anticoagulants