HAEMOSTASIS_ME

Question 1

what are the platelet constituents released during blood vessel injury?

Answer 1

• ADP
• serotonin
• epinephrine
• histamine

Question 2

which of the following does not happen to bld vessels after injury?
a. local reflex vasodilation
b. release of vasoactive substances
c. platelet adherance to subendothelial collagen fibres
d. “releasing action” of platelet constituents

Answer 2

a.
local reflex vasoconstriction

Question 3

what does prostacyclin do in haemostasis?

Answer 3

• promotes vasodilation
• ## inhibits platelet aggregation

Question 4

what is the role of the endothelium in hamostasis?

Answer 4

• procoagulant
• antithrombotic
• thromboresistant
• synthesises von willebrand factor
• synthesises tissue plasminogen activator
• synthesizes collagen
• synthesizes elastin
• synthesizes fibronectin

Question 5

what is coagulation?

Answer 5

• a process
• generates thrombin
• converst soluble fibrinogen to insoluble fibrin

Question 6

what is fibrinolysis? what aspects of blood are involved?

Answer 6

fibrinolysis is the breakdown of fibrin
- helps control coagulation’s fibrin formation
- promotes eventual removal of plug to maintain normal blood flow

Question 7

what are the characteristics of haemostasis?

Answer 7

1. interaction of blood vessel wall, adhesive glycoproteins, platelets
2. blood coagulation
3. fibrinolysis

Question 8

which is not a source of platelets?
a. bone marrow
b. liver
c. lungs
d. spleen

Answer 8

b
liver.
all others ARE

Question 9

what can cause increased platelet counts in the splenic pool?

Answer 9

epinephrine-induced splenic contractions from:
- excitement
- fear
- exercise

Question 10

which is not true of platelets?
a. involved in primary haemostasis
b. anucleated cytoplasmic pieces shed from megakaryocytes
c. cannot synthesize lipids
d. compsed of contractile proteins

Answer 10

c.
yes they can synthesise some lipids that are needed for formation of arachidonic acid

Question 11

describe platelets on romanovsky stain

Answer 11

• circulating platelets are discoid and anucleated in mammals
• non mammals- fine reddish granules
• equine platelets stain faintly

Question 12

T/F the platelets have spike like filopods

Answer 12

true

Question 13

_________ enzyme converts arachidonic acid to ____________

Answer 13

• COX (cyclooxygenase
• prostaglandin

Question 14

which is not true of thromboxane A2?
a. produced from prostaglandin PGH2
b. potent vasoconstrictor
c. important in primary haemostasis
d. synthesizes phospholipids

Answer 14

d.
doesn’t synthesize phospholipids

Question 15

what is the circulating lifespan of the platelet?

Answer 15

5-10 days

Question 16

what cytokine primarily regulates production of platelets?

Answer 16

thrombopoeitin

Question 17

organize the following in the plateltes response to vascular injury
- aggregation and secretion
- clot retraction
- facilitation and coagulation
- adhesion

Answer 17

1. vascular injury
2. adhesion
3. aggregation and secretion
4. facillitation and coagulation
5. clot retraction

Question 18

which is not true concerning the adhesion step in the response of platelets to vascular injury?
a. potassium is involved
b. platelets undergo metamorphysis
c. develop filopodia
d. vWF binds to platelet membrane

Answer 18

a.
calcium is involved

metamorphysis results in greater surface area - filopods

Question 19

list 2 aggregation agents involved in platelet response to vascular injury

Answer 19

1. thromboxane A2
2. prostaglandin

Question 20

what is primary haemostasis?

Answer 20

formation of the primary haemostatic plug after synthesis of thromboxane A2

Question 21

what are contraindications of using aspirin?

Answer 21

acetylsalicylic acid is an effective inhibitor of platelet aggregation
- inhibits COX1
- inhibits thromboxane A2 (not in bovine)
- so it will cause bleeding, so don’t give to haemorrhagic patients

Question 22

what is secondary haemostasis?

Answer 22

formation of secondary haemostatic plug
- more stable
- after thrombin formation and the platelet contractile mechanism

Question 23

which factors are intrinsic pathway?

Answer 23

• factor 12 (hageman factor)

TBC

Question 24

what two pathways are commonly considered for blood coagulation?

Answer 24

1. intrinsic
2. extrinsic

Question 25

T/F intrinsic pathway is the slower process

Answer 25

true
- and extrinsic is the faster process

Question 26

what factors initiates the common pathway?

Answer 26

the activation of factor X to factor Xa

Question 27

what is meant by cross talk?

Answer 27

products from each pathway can amplify or initiate reactions in other pathways

Question 28

what factor initiates coagulation?

Answer 28

tissue factor

Question 29

what factors form a complex that triggers the coagulation cascade?

Answer 29

• tissue factor
• 7a

Question 30

what do all other coagulation proteins except FVII circulate as?

Answer 30

zymogens

Question 31

what factors does thrombin activate and what factors does it amplify?

Answer 31

activates: 13, 11
amplifies: 5, 8

Question 32

what is the fibrinolytic enzyme?

Answer 32

plasmin

Question 33

what are inhibitors of plasmin?

Answer 33

antiplasmin

Question 34

what is the correct order?
- plasmin generation
- break down fibrin
- haemostatic plug
- plasminogen activator
- formation of fibrinogen -degradation products
- inhibit thrombin and normal platelet function
- injured endothelial celss
- tissue plasminogen activator

Answer 34

1.injured endothelial cells
2. tissue plasminogen activator
3. haemostatic plug
4. plasminogen
5. plasminogen activators
6. plasmin generation
7. breaks down fibrin/fibrinogen
8. FDPs
9. inhibit normal platelet function and action of thrombin