Ch 36 Hemostasis and Blood Coagulation

Question 1

Which characteristic of platelets ensures they adhere only to injured endothelium?

Answer 1

Glycoprotein coat

Question 2

What is the rate-limiting factor in blood coagulation?

Answer 2

Formation of prothrombin activator

Question 3

What role does vitamin K play in blood coagulation?

Answer 3

Activates prothrombin and other factors

Question 4

Which factor enables covalent bond formation in a clot?

Answer 4

Fibrin-stabilizing factor

Question 5

How does plasma differ from serum?

Answer 5

Serum lacks clotting factors and fibrinogen

Question 6

Which major components activate contraction of a clot?

Answer 6

Thrombin and calcium ions

Question 7

Which step of the intrinsic pathway requires kininogen?

Answer 7

Activation of factor XI

Question 8

Briefly, what are the most important factors for preventing clotting in the normal vascular system?

Answer 8

Endothelial surface smoothness, glycocalyx on the endothelium, and thrombomodulin bound with the endothelial surface

Question 9

in DIC, large volumes of what molecules is released into the blood?

Answer 9

Tissue factors

Question 10

Trauma to a vessel wall results immediately in what events?

Answer 10

1 is Vascular constriction, the result of local myogenic spasm, local autocoid factors from traumatized tissue, and nervous reflexes.

Question 11

What do small vessels release when damaged to halt blood flow?

Answer 11

Thromboxane A2 plays a big part in vasoconstriction of smaller vessels

Question 12

What functional characteristics of platelets contribute to their clotting abilities?

Answer 12

1. Contractile proteins actin/myosin and thrombosthenin
2. Calcium storage and enzyme synthesizing abilities
3. ATP/ADP-forming mitochondria
4. Fibrin-stabilizing factor
5. Prostaglandin synthesis
6. Growth factor
7. Glycoproteins on the outer membrane to prevent adherence to normal endothelium but adherence to injured walls
8. Phospholipids for activating processes

Question 13

What is a platelet’s half-life?

Answer 13

8-12 days

Question 14

How does the platelet plug form when they encounter a damaged vascular surface?

Answer 14

-Platelets swell and develop pseudopods and irregular shapes
-Release granules of active factors
-Become sticky to adhere to collagen and VWB factor
-Secrete ADP and form Thromboxane A2, which activate other platelets
-Platelets build up

Question 15

What happens to a clot after it has formed?

Answer 15

Either invasion by fibroblasts and formation of connective tissue through the clot
-or-
Dissolved

Question 16

Where is prothrombin formed ? Fibrinogen?

Answer 16

The liver

Question 17

How is prothrombin activator formed?

Answer 17

By the extrinsic pathway that begins with tissue trauma -and-
by the intrinsic pathway that begins in the blood itself