Platelets

Question 1

what is haemostasis?

Answer 1

the stoppage of bleeding

Question 2

what features of the epithelium prevents adhesion?

Answer 2

nitric oxide and prostaglandins are secreted and collagen covered

Question 3

what do smooth muscle cells do in the epithelium?

Answer 3

allow contraction and relaxation

Question 4

what do alpha granules do?

Answer 4

contain adhesive proteins that cause a glue-like effect

Question 5

what do dense granules do?

Answer 5

contain activators which activate other platelets

Question 6

what does the vWF receptor bind to?

Answer 6

glycoprotein 1b59

Question 7

what does collagen bind to?

Answer 7

alpha 2 beta 1 and glycoprotein 6

Question 8

what does alpha II beta III bind to?

Answer 8

fibrinogen

Question 9

how does tethering occur?

Answer 9

vWF binds to glycoprotein 1b59 causing a velcro effect

Question 10

what is activation?

Answer 10

platelet releases granule contents, which opens up adhesion receptor

Question 11

what binding occurs in activation?

Answer 11

collagen binding to glycoprotein 6

Question 12

what is adhesion?

Answer 12

single layer of platelets bind to the exposed ECM

Question 13

what binding occurs in adhesion?

Answer 13

collagen binding to alpha 2 beta 1

Question 14

what happens in secretion?

Answer 14

platelet releases ADP and TxA2 which bind to their receptors

Question 15

what is aggregation?

Answer 15

multiple layers of platelets bind to each other

Question 16

what binding occurs in aggregation?

Answer 16

fibrinogen binds to alpha 2 beta 3

Question 17

what does tirofiban do?

Answer 17

targets alpha 2 beta 3 so no aggregation

Question 18

what does aspirin and clopidogrel do?

Answer 18

inhibit activation of platelets so cannot form a clot

Question 19

what is bernard-souilier syndrome?

Answer 19

abnormality in glycoprotein 1b59 so collagen cannot bind

Question 20

what is glanzmann disease?

Answer 20

abnormality in the genes for alpha 2 beta 3

Question 21

what are the symptoms of platelet associated disease?

Answer 21

easy bruising, menstrual bleeding heavy, abdormal bleeding after surgery

Question 22

what are storage pool deficiencies?

Answer 22

caused by a lack of granules or their content or inability to empty them

Question 23

what is grey platelet syndrome?

Answer 23

lack of alpha granules and their contents

Question 24

what is zymogen?

Answer 24

inactive substance that is activated by enzymes

Question 25

what is the purpose of coagulation?

Answer 25

helps form an insoluble mesh to help strengthen the clot

Question 26

what is the key process of coagulation?

Answer 26

activation of thrombin

Question 27

what does thrombin do?

Answer 27

converts fibrinogen to fibrin

Question 28

how does initiation of coagulation begin?

Answer 28

tissue factor coming into contact with the blood

Question 29

what does the tissue factor bind to?

Answer 29

factor 7 which becomes factor 7a

Question 30

what does the binding of tissue factors cause?

Answer 30

the activation of F9 and F10

Question 31

what does activation of F9 and F10 do?

Answer 31

switches on thrombin to convert the fibrinogen to fibrin

Question 32

what does thrombin do once activated?

Answer 32

activates F5 and F8, which further activates F9 and F10

Question 33

what does tissue plasminogen activator do?

Answer 33

released into the blood to allow the clot formation to be controlled

Question 34

what is plasminogen?

Answer 34

an inhibitor that dissolves the blood clot

Question 35

what is the extrinsic pathway?

Answer 35

rapid pathway activated by external trauma that causes blood to escape

Question 36

what is the intrinsic pathway?

Answer 36

more complex, activated by inside trauma such as when collagen exposed

Question 37

what types of haemophilia are sex linked?

Answer 37

A and B

Question 38

what are the symptoms?

Answer 38

nose bleeds, brusing, gum bleeds, purpura and petechiae

Question 39

how can you test for haemophilia?

Answer 39

coagulation screening

Question 40

what is a prothrombin time test?

Answer 40

adds thromboplastin to activate factor 7 for the extrinsic pathway

Question 41

what is an activated partial thromboplastin time test?

Answer 41

activates the intrinsic pathway

Question 42

what happens if both of these tests are slow?

Answer 42

shows a defect in the common pathway