lecture 2

Question 1

What are the main components of haemostasis?

Answer 1

Blood vessel wall, platelets,
von Willebrand factor (vWF),
coagulation factors, fibrinogen
, and fibrinolysis.

Question 2

How does the blood vessel wall regulate haemostasis?

Answer 2

Endothelial cells produce negative regulators (e.g., prostacyclin, nitric oxide) and the sub-endothelium contains activators (e.g., collagen, tissue factor, vWF).

Question 3

What are the roles of von Willebrand factor in haemostasis?

Answer 3

Mediates platelet adhesion to collagen and stabilizes coagulation factor VIII.

Question 4

What are the primary functions of platelets in haemostasis?

Answer 4

Adhere to sub-endothelial proteins, activate and aggregate with other platelets, and support coagulation factor activation

Question 5

What is the coagulation cascade’s main goal?

Answer 5

To convert soluble fibrinogen into insoluble fibrin, forming a stable clot.

Question 6

Which cofactors and enzymes are required for the coagulation cascade?

Answer 6

Calcium, phospholipids, vitamin K, and serine proteases (e.g., FII, FVII, FIX, FX).

Question 7

What is fibrinogen’s role in haemostasis?

Answer 7

It binds platelets for aggregation and is polymerized by thrombin to form a fibrin clot.

Question 8

What is the role of thrombin in haemostasis?

Answer 8

Polymerizes fibrinogen into fibrin and fully activates platelets.

Question 9

How is clot formation regulated?

Answer 9

By thrombin inhibitors (e.g., antithrombin, protein C system) and the ADAMTS-13 enzyme regulating vWF adhesivity.

Question 10

What is fibrinolysis?

Answer 10

The process of clot breakdown by plasmin, producing fibrin degradation products like D-dimer.

Question 11

What are the core laboratory tests to assess haemostasis?

Answer 11

Platelet count, prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen level, and D-dimer level.

Question 12

What does a prolonged PT indicate?

Answer 12

Issues with the extrinsic pathway, often due to factor VII deficiency

Question 13

What does a prolonged APTT indicate?

Answer 13

Issues with the intrinsic pathway, involving factors VIII, IX, or XI.

Question 14

What might cause a prolonged PT and APTT?

Answer 14

Common pathway deficiencies (e.g., factors II, V, X), vitamin K deficiency, or liver dysfunction.

Question 15

What are normal plasma fibrinogen levels?

Answer 15

1.5–4.0 g/L.

Question 16

What can elevated D-dimer levels indicate?

Answer 16

Disseminated intravascular coagulation (DIC), venous thrombosis, pregnancy, sepsis, or malignancy.

Question 17

How are fibrinogen levels measured?

Answer 17

Using a clotting assay similar to PT/APTT tests.

Question 18

Why might fibrinogen levels be low?

Answer 18

Conditions such as liver disease, DIC, or massive transfusion.

Question 19

What are point-of-care tests, and when are they useful?

Answer 19

Rapid tests performed near the patient, useful in urgent settings like trauma or major surgery.

Question 20

Name a key point-of-care test for assessing haemostasis.

Answer 20

Thromboelastography (TEG) or thromboelastometry (ROTEM).

Question 21

What does thromboelastography assess?

Answer 21

The dynamic process of clot formation, strength, and fibrinolysis.

Question 22

How does thromboelastography help in clinical decision-making?

Answer 22

It identifies haemostatic defects, such as hyperfibrinolysis, to guide treatments like antifibrinolytic drugs.

Question 23

What does the CoaguChek test measure?

Answer 23

The effect of warfarin on clotting time.

Question 24

What does a D-dimer point-of-care test help diagnose?

Answer 24

The likelihood of venous thrombosis.