Chapter 14: Hemostasis

Question 1

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

Answer 1

Hemostasis

Question 2

Clotting

Answer 2

Coagulation

Question 3

Bleeding into the tissues

Answer 3

hemorrhage

Question 4

What forms at a localized injury site to stop bleeding?

Answer 4

hemostat plug

Question 5

clot

Answer 5

hemostat plug

Question 6

What are the five factors involved in hemostasis?

Answer 6

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.

Question 7

What happens to small blood vessels when they are injured?

Answer 7

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.

Question 8

The smallest type of blood cells

Answer 8

platelets

Question 9

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

Answer 9

platelets

Question 10

What allows platelets to bind to an injury site?

Answer 10

Exposure of underlying connective tissue of endothelium in blood vessels

Question 11

What three important functions do platelets perform?

Answer 11

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.

Question 12

Platelet plug of a defect in a vessel wall

Answer 12

Primary hemostasis

Question 13

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

Answer 13

megakaryocytes

Question 14

How long do platelets survive in circulation?

Answer 14

~10 days

Question 15

What removes platelets when they are worn out?

Answer 15

Macrophages in the spleen

Question 16

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

Answer 16

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

Question 17

Activation of ____________ initiates blood coagulation via the intrinsic system.

Answer 17

platelets

Question 18

Another name for platelets

Answer 18

thrombocytes

Question 19

What does Plavix do?

Answer 19

Prevents platelets from sticking

Question 20

Which medication prevents platelets from sticking?

Answer 20

Plavix

Question 21

Which medication irreversibly inhibits platelet function?

Answer 21

Aspirin

Question 22

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

Answer 22

Coagulation factors

Question 23

What do activated coagulation factors do?

Answer 23

Produce a blood clot

Question 24

What is the mechanism of blood clot formation?

Answer 24

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

Question 25

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

Answer 25

Secondary hemostasis

Question 26

Why are coagulation inhibitors important?

Answer 26

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

Question 27

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

Answer 27

Antithrombin III

Question 28

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

Answer 28

Protein C and Protein S

Question 29

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

Answer 29

fibrinolysis

Question 30

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

Answer 30

fibrinolysin

Question 31

What is another name for fibrinolysin?

Answer 31

Plasmin

Question 32

What activates plasmin (fibrinolysin)?

Answer 32

activated plasminogen (profibrinolysin) in blood plasma

Question 33

How is plasminogen (profibrinolysin) activated?

Answer 33

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

Question 34

What produces thrombin?

Answer 34

The coagulation cascade

Question 35

Where are tissue plasminogen activators released from?

Answer 35

endothelium at the clot site

Question 36

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

Answer 36

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

Question 37

Breakdown of blood clots

Answer 37

thrombolysis

Question 38

Which phases of blood coagulation require Ca2+?

Answer 38

All of them.

Question 39

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

Answer 39

True

Question 40

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

Answer 40

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