08 Hemostasis Flashcards Preview

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Flashcards in 08 Hemostasis Deck (33):
1

Process of blot clot formation at the site of vessel injury

Hemostasis

2

Average time of hemostasis

20 minutes

3

Phases of hemostasis

Primary
Secondary
Fibrinolysis

4

Initial step in stopping the bleeding after a blood vessel injury

Primary hemostasis

5

Fast-acting (~5 minutes)
Weak and not permanent
Interaction of platelet with blood vessel in which the end product is a platelet clot

Primary hemostasis

6

Activation of clotting factors

Secondary hemostasis

7

Causes fibrin to cluster
Involves RBCs and WBCs in creating a permanent clot
Around 10 minutes

Secondary hemostasis

8

Healing of the cut blood vessel and the blood clot dissolves after a few days

Fibrinolysis

9

Elements of hemostasis

Vascular walls
Endothelial cells
Platelets

10

Prevent loss in the blood vessel

Vascular walls

11

Negatively charged to repel circulating proteins and platelets
Produces and released substances that inhibit or promote platelets, coagulation and fibrinolysis
Ex: collagen, fibronectin

Endothelial cells

12

Produced from bone marrow
Contain granules that help in coagulation

Platelets

13

Maintain shape of platelets as discoid
Microtubules

Cytoskeleton

14

Actin filaments (responsible for change in shape of platelet) and glycoprotein 1B (adhesion)

Membrane skeleton

15

Plays a role in the activation of the cell and platelets surrounding activated platelets
Invagination of the plasma membrane that appears to be a tunnel

Surface connected open canalicular system

16

Highly specialized membrane
Remnant of smooth endoplasmic reticulum
Storage for calcium

Dense tubular system

17

Steps of primary hemostasis

Vasoconstriction
Platelet plug formation

18

Aka vascular spasm phase
Initial response to blood vessel endothelium injury

Vasoconstriction

19

Vasoconstriction is triggered by:

Direct injury to vascular smooth muscle
Chemicals released by endothelial cells
Platelets
Reflexes initiated by local pain receptors

20

Aka platelet phase
Platelets adhere to damaged endothelium
Regulated by thromboregulation
Temporary seals the break in the vessel wall

Platelet plug formation

21

Steps in platelet plug formation

Adhesion
Activation
Aggregation

22

Strong activating agent
Exposed collagen binds with vWF

Platelet adhesion

23

First adhesion site of platelet to damaged endothelium

Glycoprotein 1B

24

Large multimeric glycoprotein, circulates in the plasma and found in platelets

vWF

25

Release of alpha and dense granules
Release of thromoboxane A2
Enhance subsequent aggregation and increase surface area available for interaction with coagulation factors
Conformational change in platelet GPIIB/IIIA

Activation

26

Promoted by bridging interactions between fibrinogen and GPIIB/IIIA receptors on adjacent platelets

Platelet aggregation/hemostatic plug

27

Aka coagulation phase
Conversion of fibrinogen to fibrin
Rapid response reinforces the platelet plugs

Secondary hemostasis

28

Secondary hemostasis process

Initiation
Amplification
Propagation

29

Clot is removed following the healing of wound

Fibrinolysis

30

Absence of vWF hence no adhesion

von Willebrand deficiency

31

Deficiency in GP1B
No receptors attached to platelet

Bernard-Soulier syndrome

32

Deficiency in GPIIb-IIIa complex
No aggregation

Glanzmann thrombasthenia

33

Difficulty in making the platelet plug
Previous viral infection
Immune-mediated
Besides producing antibodies against viral infection, antibodies which bind to the platelets are also produced

Immune thrombocytopenic purpura