Block 4 lecture 5 coagulation

Question 1

What is Haemostasis?

Answer 1

In a physiological state, maintain fluid blood flow within the vasculature:
On vessel injury/trauma, limit/arrest bleeding by forming a clot at the site of
injury while maintaining blood flow in the rest of the vessel
Removal of the blood clot following wound healing

Question 2

What is Thrombosis?

Answer 2

The pathological manifestation of haemostasis. Causes restriction or blockage of blood vessel, causing hypoxia and tissue damage. Thrombi can also dislodge, leading to embolization.

Question 3

Three stages of Haemostasis?

Answer 3

Vascular Spasm
Platelet Plug Formation
Coagulation

Question 4

what happens during vascular spasm?

Answer 4

vessels constrict
rreduced blood flow to damaged area
reduces blood loss

Question 5

what happens during platelet plug formation?

Answer 5

platelets bind to damaged vessel wall

Question 6

what happens during coagulation?

Answer 6

fibrinogen is converted to fibrin

Question 7

what are platelets?

Answer 7

Platelets are small fragments of megakaryocyte cytoplasm

Question 8

how are old platelets destroyed?

Answer 8

Old platelets are destroyed by Kupfer cells in the liver or by phagocytosis in the spleen

Question 9

The critical components of platelets are?

Answer 9

Membrane proteins
Secretory granules
Surface-connected open cannalicular system (SCOCS)

Question 10

do platelets have a nucleus?

Answer 10

As they don’t have a nucleus, platelets contain all the factors required for their function.

Question 11

what do a-granules contain?

Answer 11

Adhesive proteins (fibrinogen, fibronectin, vWF)
Platelet-specific proteins (PF4, PDGF)
Membrane proteins (GPIIaIIIb, GPIb/IX/V)
a-granule-specific proteins (P-selectin)

Question 12

what are the types of platelet granule?

Answer 12

alpha

dense

Question 13

what do platelet dense granules contain?

Answer 13

Vasoconstructive agents (serotonin)
Platelet agonists (ADP, ATP)
Calcium and Magnesium

Question 14

which part of the endothelium do the platelets bind to?

Answer 14

sub endothelium

Question 15

what happens when platelets roll of vWF?

Answer 15

become more adhesive and activated

Question 16

what does firmer platelet adhesion lead to?

Answer 16

This firmer adhesion initiates platelet activation, resulting in granule relsease and conformation changes in specific adhesion molecules, leading to strong adhesion, shape change and further activation.

Question 17

what happens to the newly recruited platelets to the plug?

Answer 17

they change shape, allowing for greater platelet-platelet interactions, especially via fibrinogen cross-bridges, which bind to GPIIaIIIb

Question 18

what is the group name for coagulation factors?

Answer 18

zygomens

Question 19

what is the coagulation extrinsic pathway usually caused by?

Answer 19

The extrinsic pathway, which normally is triggered by trauma

Question 20

what is the coagulation intrinsic pathway usually caused by?

Answer 20

The intrinsic pathway, which begins in the bloodstream and is triggered by internal damage to the wall of the vessel.

Question 21

what does the platelet monolayer release to recruit more platelets?

Answer 21

The activated platelet monolayer release platelet agonists such as ADP, thromboxane A2 and adhesive proteins, such as fibrinogen, which recruits further platelets to the developing plug.

Question 22

what do active factor 10 and factor 5 form?

Answer 22

activated prothrombin

Question 23

what is the enzyme that converts fibrin into fibrinogen?

Answer 23

thrombin

Question 24

what regulates the coagulation pathway?

Answer 24

anticoagulants e.g. tissue factor pathway inhibitor, this stops active factor 10
antithrombins

Question 25

what happens in a coagulation test?

Answer 25

ball is put in coagulometer and its speed is monitored

Question 26

coagulation tests?

Answer 26

Prothrombin time (PT)
Partial Thromboplastin Time (PTT)

Question 27

what is Thrombocytopenia?

Answer 27

Thrombocytopenia is the term used to describe a condition of low circulating platelets

Question 28

what happens in immune thrombocytopenia

Answer 28

antibodies to platelets proteins, usually GP-IIbIIIa or Ib/IX, are found in the plasma. The IgG-coated platelets are then cleared either by splenic macrophages or Kupfer cells in the liver.

Question 29

what is Glanzmann’s Thrombasthenia?

Answer 29

Glanzmann’s Thrombasthenia (GT) is an autosomal recessive bleeding syndrome affecting the megakaryocyte lineage and characterized by a lack of platelet aggregation

Question 30

what is hemophilia?

Answer 30

Haemophilia is a recessive sex-linked X-chromosome disorder characterised by changes in clotting proteins

Question 31

how does aspirin work for people suffering from blood disorders?

Answer 31

Aspirin inhibits platelet cyclooxygenase, a key enzyme in thromboxane A2 (TXA2) generation. Thromboxane A2 triggers reactions that lead to platelet activation and aggregation. Anti-Thrombotic and Anti-Inflammatory

Question 32

ADP Receptor Antagonists?

Answer 32

clopidogrel, prodrug, reduce thrombotic events

Question 33

what do anticoagulants do?

Answer 33

reduce formation of fibrin

Question 34

what does heparin do?

Answer 34

binds to antithrombin causing a conformational change increasing its binding affinity for FXa and thrombin

Question 35

what anticoagulant is a vitamin K antagonist?

Answer 35

warfarin