Hemostasis

Question 1

hemostasis

Answer 1

stopping blood loss in response to vascular injury

Question 2

list the 4 general phases in the process of hemostasis

Answer 2

1. vascular constriction
2. formation of platelet plug
3. formation of blood clot
4. fibrous organization

Question 3

describe and discuss vascular constriction

Answer 3

response to injury to help reduce blood flow/bleeding

Question 4

describe and discuss formation of the platelet plug

Answer 4

primary hemostasis, platelet adhesion and aggregation, w/ help of vWF and fibrinogen (acts as a bridge for platelets)

Question 5

describe and discuss formation of the blood clot

Answer 5

secondary hemostasis, activation of clotting factors (clotting cascade), enables fibrin to collect at site of platelet plug

Question 6

describe and discuss fibrous organization

Answer 6

clot retraction and clot destruction. activation of lytic enzymes to break up clot and restore normal blood flow through healed vessel

Question 7

thrombosis

Answer 7

formation of a clot, usually w/i lumen of vessel (can be arterial or venous)

Question 8

embolus

Answer 8

an unattached thrombus fragment

Question 9

atherosclerosis

Answer 9

pathologic deposition of lipids and smooth muscle proliferation inside an artery

Question 10

infarction

Answer 10

dead tissue, can be caused by ischemia due to thrombosis that completely blocks lumen of blood vessel

Question 11

petechiae

Answer 11

red-purple, non-blanchable discoloration less than 0.5cm in diameter (small purpura), caused by intravascular defects, infection

Question 12

purpura

Answer 12

red-purple, non-blanchable discoloration larger than 0.5cm in diameter (large petechiae), caused by intravascular defects, inection

Question 13

ecchymoses

Answer 13

red-purple, non-blanchable discoloration of variable size, caused by vascular wall destruction, trauma, vasculitis

Question 14

vasculitis

Answer 14

inflammation of the vasculature

Question 15

hematoma

Answer 15

collection of blood out of the vessels in tissues

Question 16

discuss the 5 steps in the platelet activation process

Answer 16

1. adhesion: vWB promotes platelet aggregation
2. aggregation: fibrinogen bridges platelets
3. spreading: platelets change shape
4. granular secretion: secretion from platelets mediates plug formation
5. pro-coagulant phospholipid exposure

Question 17

life span of platelets

Answer 17

7-10 days

Question 18

discuss how vWB factor and platelets interact w/ each other

Answer 18

platelets adhere to vWB factor via vWB factor receptors on their surface, this facilitates formation of the platelet plug in primary hemostasis.

Question 19

discuss the breakdown of the fibrin clot

Answer 19

plasminogen is activated to plasmin (a bunch of factors act to do this), plasmin cleaves fibrin into fibrin degredation products, clot breaks down via fibrinolysis

Question 20

discuss the conversion of prothrombin to thrombin

Answer 20

prothrombin circulates in plasma, exposed TF activates prothrombin to thrombin. thrombin in turn activates fibrinogen into fibrin to create clot.

Question 21

discuss the conversion of fibrinogen to fibrin

Answer 21

fibrinogen is cleaved into fibrin by thrombin.

Question 22

discuss the role of thrombin in clot formation

Answer 22

fibrin binds platelets to help them change conformation. platelet plug forms by bridging of platelets via fibrinogen. thrombin also activates fibrinogen to fibrin to form the final product, a clot.

Question 23

intrinsic pathway

Answer 23

platelet factor pathway, activated by trauma inside vascular system, causes platelet factors to be released, slower than extrinsic pathway.

Question 24

extrinsic pathway

Answer 24

initiates the coag. cascade in vivo. TF is expressed on damaged endothelial cells of blood vessels, this initiates cascade of clotting factors. faster than intrinsic pathway.

Question 25

common pathway

Answer 25

convergence of intrinsic and extrinsic pathways, ultimately leads to formation of a fibrin clot.

Question 26

vitamin K is important for formation of which proteins?

Answer 26

1. prothrombin
2. factors VII, IX, X
3. protein C

Question 27

what are two effects of vitamin K deficiency on clotting?

Answer 27

1. affects intrinsic and extrinsic pathways

2. causes increased PT and PTT

Question 28

what are the 3 types of hemophilia we have studied?

Answer 28

hemophilia a: factor VIII deficiency
hemophilia b: factor IX deficiency
vWB disease: impaired platelet aggregation

Question 29

what are the clinical S/S of vWB disease?

Answer 29

muco-cutaneous bleeding. petechiae and easy bruising, most common cause of elevated PTT

Question 30

DVT

Answer 30

deep vein thrombosis, thrombus occurs in deep lower extremity vein, has potential to detach and become embolus

Question 31

pulmonary embolism

Answer 31

embolus migrates to pulmonary artery and become lodged there

Question 32

thrombocytopenia

Answer 32

abnormal decrease in platelets, may results in excessive bleeding

Question 33

disseminated intravascular coagulation

Answer 33

clotting condition, activation of both pathways causes small clots develop in blood stream and block vessels, depletes platelets and clotting factors, can lead to excessive bleeding.

Question 34

bleeding time

Answer 34

cause small cuts in pt. under BP cuff that is inflated on upper arm, blotted every 30 seconds

Question 35

platelet count

Answer 35

part of CBC, normal range ~150,000-300,000/microleter

Question 36

PTT

Answer 36

partial thromboplastin time, clotting time in seconds, measures intrinsic pathway, good test for monitoring heparin therapy

Question 37

PT

Answer 37

prothrombin time, clotting time in seconds, measures extrinsic pathway, good for monitoring warfarin therapy

Question 38

D-dimer

Answer 38

detects presence of d-dimer (fibrin degradation product), positive results may indicate presence of thrombus (e.g. DVT or PE)

Question 39

platelet function test

Answer 39

determines 3 things:

1. platelet ability to aggregate
2. strength of blot
3. responsiveness of platelets to chemotactic signals

useful in diagnosing thrombotic deficiencies (e.g. vWB disease)

Question 40

what factors are involved in the intrinsic pathway

Answer 40

VIII, IX, X, XI, XII

Question 41

what factors are involved in the extrinsic pathway

Answer 41

VII

Question 42

describe how TFPI works to limit clot extension

Answer 42

targets factor VIIa-TF complex, inhibits extrinsic pathway

Question 43

describe how antithrombin works to limit clot extension

Answer 43

targets heparin and endogenous glycoconjugates, inhibits factors VIIa, IXa, XIa, and thrombin

Question 44

describe how activated protein C works to limit clot extension

Answer 44

targets factor V and VIII, inhibits formation of factor Xa and thrombin

Question 45

describe how plasmin works to limit clot extension

Answer 45

targets fibrin, causes fibrinolysis to occur

Question 46

factor V leiden

Answer 46

genetic mutation, increases pathogenic clot formation by 5-7x if heterozygous, 80x if homozygous, often goes undiagnosed. OCP, infection, smoking, surgery contribute to risk of developing a clot w/ this condition.