Chapter 14: Hemostasis Flashcards

1
Q

The arrest of bleeding caused by activation of the blood coagulation mechanism

A

Hemostasis

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2
Q

Clotting

A

Coagulation

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3
Q

Bleeding into the tissues

A

hemorrhage

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4
Q

What forms at a localized injury site to stop bleeding?

A

hemostat plug

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5
Q

clot

A

hemostat plug

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6
Q

What are the five factors involved in hemostasis?

A

1) Integrity of small blood vessels and lining cells.
2) Adequate #s of platelets
3) Normal amounts of coagulation factors.
4) Normal amounts of coagulation inhibitors.
5) Adequate amount of calcium ions in blood.

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7
Q

What happens to small blood vessels when they are injured?

A

1) Constrict
2) Exposure of underlying connective tissue of endothelium allows platelets to bind and activates the coagulation mechanism.
3) Endothelial cells release thrombin (T) and von Willebrand factor.

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8
Q

The smallest type of blood cells

A

platelets

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9
Q

Cells that circulate in the blood and bind together when they recognize damaged vessels.

A

platelets

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10
Q

What allows platelets to bind to an injury site?

A

Exposure of underlying connective tissue of endothelium in blood vessels

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11
Q

What three important functions do platelets perform?

A

1) Plug a damaged vessel wall (primary hemostasis)
2) Liberate vasoconstrictors and compounds that cause platelets to aggregate
3) Release phospholipids to initiate blood coagulation.

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12
Q

Platelet plug of a defect in a vessel wall

A

Primary hemostasis

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13
Q

What are the precursors of platelets in the the bone marrow?

A

megakaryocytes

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14
Q

How long do platelets survive in circulation?

A

~10 days

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15
Q

What removes platelets when they are worn out?

A

Macrophages in the spleen

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16
Q

What happens to platelets when they encounter a roughened/damaged endothelial surface?

A

They become swollen and sticky, extend pseudopdial processes, and release substances that enhance platelet participation in coagulation.

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17
Q

Activation of ____________ initiates blood coagulation via the intrinsic system.

A

platelets

18
Q

Another name for platelets

A

thrombocytes

19
Q

What does Plavix do?

A

Prevents platelets from sticking

20
Q

Which medication prevents platelets from sticking?

A

Plavix

21
Q

Which medication irreversibly inhibits platelet function?

A

Aspirin

22
Q

Proteins in blood plasma that, when activated, interact to produce a blood clot

A

Coagulation factors

23
Q

What do activated coagulation factors do?

A

Produce a blood clot

24
Q

What is the mechanism of blood clot formation?

A

1) Activation of an inactive precursor to an active component
2) Active component activates next member of chain, resulting in a reaction cascade.

25
Q

Conversion of the platelet aggregate plug into a more stable fibrin-containing clot

A

Secondary hemostasis

26
Q

Why are coagulation inhibitors important?

A

They restrict the clotting process to a limited area (keep it localized)

27
Q

Which important coagulation inhibitor inhibits thrombin and other activated coagulation factors generated in the clotting process?

A

Antithrombin III

28
Q

Which two coagulation inhibitors work together to inactivate factors V and VIII?

A

Protein C and Protein S

29
Q

What process eventually dissolves the fibrin in a clot after the clot has served its purpose?

A

fibrinolysis

30
Q

What enzyme eventually dissolves the fibrin in a clot after the clot has served its purpose?

A

fibrinolysin

31
Q

What is another name for fibrinolysin?

A

Plasmin

32
Q

What activates plasmin (fibrinolysin)?

A

activated plasminogen (profibrinolysin) in blood plasma

33
Q

How is plasminogen (profibrinolysin) activated?

A

By plasminogen activators (PA): 1) thrombin and 2) tissue PA

34
Q

What produces thrombin?

A

The coagulation cascade

35
Q

Where are tissue plasminogen activators released from?

A

endothelium at the clot site

36
Q

What two medications are used to dissolve clots in the coronary arteries of heart attack patients?

A

tPA (tissue plasminogen activator) and streptokinase (a thrombolytic medication)

37
Q

Breakdown of blood clots

A

thrombolysis

38
Q

Which phases of blood coagulation require Ca2+?

A

All of them.

39
Q

True or false: Blood will not clot in the absence of calcium.

A

True

40
Q

Why would a person never die from impaired blood clotting due to low Ca2+ levels?

A

Because Ca2+ levels low enough to impair clotting would be incompatible with life.