Primary Haemostasis Flashcards Preview

Basic Haemotology (1204) > Primary Haemostasis > Flashcards

Flashcards in Primary Haemostasis Deck (40):
1

How are platelets formed

Fragmentation of megakaryocytes

2

What is the name of the process by which platelets are formed

Endoreduplication

3

What 2 substances control endoreduplication

Thrombopoietin
Colony stimulating factors

4

How long does endoreduplication last

10 days in in humans

5

True or false, platelets are nucleated biconvex discs

False, they are non nucleated

6

Where do the platelets remain for the duration of the their lifetime

Intravascular space

7

How long is the lifetime of platelets

8-10 days

8

What functions do platelets have

Adhesive and contractile functions

9

What are the growth phases of platelets

Stem cell, multipotent progenitor cell, commited megakaryocyte, immature megakaryocyte, mature megakaryocyte, platelets

10

What is the main hematopoietic growth factor that regulates endoreduplication

Thrombopoietin

11

Where is thrombopoietin produced

Liver and kidney

12

What does the hormone thrombopoietin stimulate

Production and differentiation of megakaryocytes

13

What are the specific antigens on platelets called ?

HPA

14

What is the name of the three granules in platelets

Alpha, dense, lysosomes

15

What are the names of the content in dense granules

ADP/ATP
Calcium
Serotonin

16

What are the functions of the Dense contents

ADP/ATP- PLT agonist
Calcium- Regulates PLT activation
Serotonin- Promotes Vasoconstriction

17

What is the function of the the lysosomes contents

Proteolytic, hydrolytic enzymes - digest vessel wall matrix and debris

18

What are the functions of the alpha content

Thromboglobulin (beta- TG)- inhibit heparin; vessel repair
PF4- inhibit heparin
PDGF- vessel repair
Fibrinogen, Factors V and VIII- fibrin formation
vWF- PLT Adhesion
Plasminogen- Precursors of plasmin (fibrinolysis)
Alpha1-antiplasmin- Plasmin inhibitors
HMWK- contact activation; intrinsic coagulation path
Fibronectin- Promotes PLT spreading

19

What is the normal platelet count cells/mm^3

100,000-400,000

20

Term used to describe Platelet count <100,000

Thrombocytopenia

21

What is the platelet count for mild thrombocytopenia

50,000-100,000

22

What is the platelet count for severe thrombocytopenia

<50,000

23

What substance inhibits platelet aggregation

Prostacyclin

24

What process occurs when endothelium is ruptured

Haemostasis

25

What are the steps in primary Haemostasis

Vasospasm
Platelet plug formation
Blood coagulation
Fibrinolysis

26

What is the role of the endothelial walls

Protecting blood from coagulation
Platelets from subendothelial aggregating substances

27

What is he function of the tissue factor

Initiate coagulation

28

What blood protein and sub endothelial connective tissue functions as a platelet subendothelium adhesion carriage of VIII

Collagen type 2 and 4
Von Willebrand factor

29

What subendothelial connective tissue and blood protein, functions to inhibit blood coagulation

Basement memebrane, microfibrils
Antithrombin 3 and protein C activation

30

What are the steps in primary haemostasis after an injury

Vasoconstriction (immediately)
Platelet adhesion (seconds)
Platelet aggregation(minutes)

31

What are the steps in secondary Haemostasis after an injury

Activation of coagulation factors
Formation of fibrin(minutes)

32

What occurs in fibrinolysis

Activation of fibrinolysis (minutes)
Lysis of the clot (hours)

33

What 3 substances functions in the adhesive property of platelets

GPl (collagen)
GPIb
VWF

34

What two substances functions in stimulating the aggregation properties of platelets

ADP and thromboxane A2

35

What occurs in the activation role of platelets

Change in shape (pseudopodia)
Secretions of contents like ADP, serotonin, fibrinogen thromboxane A2

36

Synthesis of prostacyclin and thromboxane, are mediated by changes in the concentration of _________ in platelets via stimulation or inhibitor of the enzyme ___________.

Cyclic AMP
Adenylate cyclase

37

High levels of cyclic AMP lead to ______ free calcium ion concentrations and prevent _______ and ______

Low
Aggregation and adhesion

38

After aggregation, what occurs

Platelets rearrange themselves to reveal binding sites for coagulation protein

39

In the platelet procoagulation action what two substances are formed

Factor Xa and thrombin

40

What ion activated the conversion of prothrombin to thrombin

Ca2+