1: Haemostasis Flashcards Preview

Haematology Week 2 2018/19 > 1: Haemostasis > Flashcards

Flashcards in 1: Haemostasis Deck (48)
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1

What is haemostasis?

Arrest of bleeding while maintaining vascular patency

2

What is primary haemostasis?

Formation of a fibrin plug at a site of bleeding

3

Which protein is involved in secondary haemostasis?

Fibrin

forms a CLOT around the platelet plug

4

Which two processes keep haemostasis in check after the formation of the fibrin clot?

Fibrinolysis

Anticoagulation

5

Which blood cells form platelets?

Megakaryocytes

6

Are platelets cells?

No

Buds of cytoplasm from megakaryocytes

7

How long do platelets last for?

Why is this clinically relevant?

7 - 10 days

Anti-platelets e.g aspirin are stopped 7-10 days before surgery to avoid bleeding

8

What is the accumulation of platelets at a site of injury called?

Aggregation

9

Platelets ___ to form a plug in ___ haemostasis.

aggregate

primary haemostasis

10

Why do elderly patients bruise easily?

Express less collagen at sites of injury

Leading to less efficient haemostasis

11

What is Vitamin C required to produce?

What is Vitamin C deficiency called?

Collagen

Scurvy

12

What is a reduced number of platelets called?

Thrombocytopaenia

13

What proteins encourage platelet adhesion at the site of an injury?

Collagen

Von Willebrand factor

14

What is an autoimmune disease which causes a rash and thrombocytopaenia?

Immune thrombocytopaenic purpura

15

What symptoms may a patient have if they cannot form a platelet plug?

Bruising

Purpuric rash

Exaggerated bleeding

16

What diseases, causing platelet dysfunction, can cause abnormal bleeding?

Vitamin C deficiency (reduced collagen expression)

Autoimmune thrombocytopaenic purpura

Von Willebrand disease

17

Why do purpuric rashes often appear on the lower limbs?

Oncotic pressure due to gravity

Fluid (inc. blood) squeezed out of capillaries

Elderly / thrombocytopaenic patients cannot stop this "bleeding"

18

What is measured to diagnosed primary haemostasis?

Platelet count

19

What molecules are platelets made of?

Phosphoplipids

Which are negatively charged

20

Which ion is secreted by platelets?

Calcium

Ca2+, binds to -ve phospholipids

21

Which proteins bind to Ca2+ ions, found on the platelet plug, to cause secondary haemostasis?

Clotting factors

22

Which clotting factors initiate coagulation?

Tissue factor and Factor VIIa

23

Which two clotting factors convert prothrombin to thrombin?

Factor V and Factor Xa

24

___ ___ and factor ___ initiate clotting.

Tissue factor and Factor VIIa

25

The factor V/Xa complex converts ___ to ___.

prothrombin to thrombin

26

Thrombin converts ___ to ___, forming a clot.

fibrinogen to fibrin

27

What converts fibrinogen to fibrin to form a clot?

Thrombin

which is produced from prothrombin by factors V/Xa

28

Apart from converting fibrinogen to fibrin to form a clot, what else does thrombin activate during coagulation?

Factors VIII/IXa

Which reactivates Factor V/Xa

Which converts more prothrombin to thrombin...

29

Which protein, generated midway through the clotting cascade, activates other clotting factors?

Thrombin

30

What is the end product of the clotting cascade?

Fibrin

forming a clot