Lect 4 - Haemostasis

Question 1

Coagulation is the process that results in the generation of

Answer 1

Thrombin

Question 2

Thrombin converts what into what

Answer 2

Soluble fibrinogen to insoluble fibrin

Question 3

Fibrin along with __ is needed to do what?

Answer 3

Platelets

Arrest bleeding

Question 4

When coagulation pathways are activated, fibrinolysis is also. What is fibrinolysis?

Answer 4

The process of breakdown of fibrin

Question 5

Platelets adhered to exposed subendothelial collagen fibres cause a “release action” of platelet constituents such as [4]

Answer 5

ADP
Serotonin
Epinephrine
Histamine

Question 6

Endothelium, particularly of the pulmonary micro-circulation actively removes substances from the circulation that promote platelet aggregation such as

Answer 6

Prostaglandin F1
Serotonin
Adenine nucleotides
Bradykinin
Angiotensin-1

Question 7

Also, all layers of blood vessels, but especially the endothelium and the intima synthesize and release [1] potent inhibitor of platelet aggregation and promotor of vasodilation

Answer 7

Prostacyclin (Prostaglandin I2)

Question 8

The endothelial surface is protected from thrombresistance by a carbohydrate rich cell coat called

Answer 8

Gylcocalyx

Question 9

The endothelium produces __, a potent vasodilator which also inhibits platelet adhesion and aggregation

Answer 9

Nitric oxide

Question 10

What are platelets? Where do they come from?

Answer 10

Anucleate cytoplasmic pieces shed from megakaryocytes mainly in the bone marrow. Lungs and Spleen are also sources of platelets.

Question 11

They are the smallest formed elements in stained blood smears stained with what stain

Answer 11

Romanowsky

Question 12

Circulating platelets in mammals vs non mammals

Answer 12

Mammals - Discoid and anucleated

Non mammals - have nuclei

Question 13

How do equine platelets appear under a stain

Answer 13

Faint and may be difficult to see

Question 14

Platelets can synthesize certain lipids, which are needed for the formation

Answer 14

AA > Prostaglandin PGH2 via COX > TxA2

Question 15

The lifespan of the platelet is

Answer 15

5-10days

Question 16

Platelet production is regulated by

Answer 16

Thrombopoietin

Question 17

Platelets adhere to exposed sub-endothelial collagen, mostly via what bond

Answer 17

von Willebrand factor

Question 18

von Willebrand factor bonds to the platelet receptor ___

Answer 18

Glycoprotein 1b

Question 19

vWF is a protein formed by what? [2] and found where [2]

Answer 19

Endothelial cells and megakaryocytes

Platelets and plasma

Question 20

After adhesion to the site of vascular injury, platelets adhere to each other via bind to fibrinogen and vWF interacting with certain platelet surface receptors, rapidly enlarging the platelet plug. Fibrinogen interacts with these surface receptors [2]

Answer 20

IIB and IIIA

Question 21

Aggregating platelets release [2] which promotes further platelet adherence. They also begin synthesizing [1] a prostaglandin that causes irreversible platelet aggregation and intense local vasoconstriction. The platelet plug formed at this point is unstable and is called the [1]. The process by which it is formed is called [1]

Answer 21

ADP and Fibrinogen

TxA2

Primary hemostatic plug

Primary haemostasis

Question 22

When platelets are activated, certain phospholipids collectively called [1], move from the inner to outer membrane of the platelet, and are available for use as cofactors in the coagulation pathway

Answer 22

Platelet factor 3

Question 23

[1] (formed during the process of coagulation) stimulates [1] formation with the primary platelet plug. This, along with the platelet contractile mechanism, result in formation of a [1] (secondary haemostatic plug– this is called [1]

Answer 23

Thrombin

Fibrin

A stable plug

Secondary haemostasis

Question 24

Aspirin is an effective inhibitor of the platelet release reaction by acetylating COX I and inhibiting TxA2 production except in what species

Answer 24

Bovine

Question 25

Fibrinolysis is achieved by the fibrinolytic enzyme

Answer 25

Plasmin

Question 26

The action of plasmin on fibrin or fibrinogen results in the formation of

Answer 26

FDP (Fibrin degradation products)

Question 27

Plasmin generation is strongly inhibited in plasma by substances called

Answer 27

Antiplasmins

Question 28

Anti-thrombin III (AT III) which accounts for 80% of the naturally occurring plasma inhibitory activity. The anti-coagulation activity of AT III is greatly enhanced by [1], particularly against factor [2]

Answer 28

Heparin

Xa and thrombin

Question 29

Antithrombin III is synthesized where

Answer 29

Liver

Question 30

These [2] vitamin K dependant factors destroy Va and VIIIa

Answer 30

Protein C and S

Question 31

Platelet clumping/aggregation leading to pseudothrombocytpenia occurs frequently and is most commonly seen in what species

Answer 31

Cats

Question 32

This species has platelets of variable size which can be as large as an RBC

Answer 32

Feline

Question 33

EDTA- induced clumping has occasionally been reported in what species

Answer 33

Horse

Question 34

Which breed of dog have natural lower platelet count

Answer 34

Greyhounds

Question 35

Anaplasma platys infection (infects platelets and causes what in dogs

Answer 35

Cyclic thrombocytopenia

Question 36

The most inherited bleeding disorder in dogs but rare in cattle, cats and horses

Answer 36

vWD

Question 37

What breed of dog is highly affected by vWD

Answer 37

Doberman pinchers

Question 38

The Bernard - Soulier Syndrome is

Answer 38

Abnormality or a deficiency of platelet glycoprotein 1b. Affected animals exhibit mild to moderate bleeding. Bleeding time (BMBT) is prolonged but clot retraction is normal.