2️⃣ Hemostasis

Question 1

Define hemostasis and its roles.

Answer 1

The process preventing bleeding while keeping blood fluid in circulation; prevents blood loss and aids vascular repair.

Question 2

What are the four stages of hemostasis?

Answer 2

1. Vasoconstriction; 2. Primary hemostasis (platelet plug); 3. Secondary hemostasis (coagulation cascade → fibrin); 4. Clot stabilization & resorption (fibrin cross-linking, fibrinolysis).

Question 3

Describe vasoconstriction in hemostasis.

Answer 3

Immediate, transient reduction of blood flow via neural and local mediators.

Question 4

How do platelets form the primary hemostatic plug?

Answer 4

Platelet adhesion to vWF/collagen, activation → spiky shape, recruitment, and aggregation via fibrinogen bridges.

Question 5

Outline the coagulation cascade’s overall process.

Answer 5

Initiated by TF exposure → FVII activation → thrombin generation → fibrin formation; amplification and propagation via feedback loops stabilize the clot.

Question 6

What occurs during initiation of coagulation?

Answer 6

TF from damaged endothelium binds FVIIa, activating FIX and FX → FXa generation.

Question 7

What happens in amplification and propagation phases?

Answer 7

Amplification: FXa/FVa converts prothrombin to thrombin; Thrombin activates FVIII, FXI; Propagation: FVIIIa/FIXa complex → burst thrombin formation → fibrinogen to fibrin.

Question 8

How is the clot stabilized and later resorbed?

Answer 8

Platelets and fibrin contract for a solid plug; plasmin (from plasminogen via tPA) breaks down fibrin, dissolving the clot.

Question 9

Define hemorrhage and list its causes.

Answer 9

Failure of hemostasis leading to blood loss, hypoxia, possible death; causes include vessel rupture, clotting factor deficiencies (e.g., hemophilia), and platelet dysfunction (aspirin, vWF mutation).

Question 10

Describe Hemophilia A’s cause, severity, symptoms, and treatment.

Answer 10

X-linked recessive FVIII deficiency; severe <1%, moderate 2–5%, mild 6–50% activity; symptoms: bruising, joint bleeds; treated with recombinant FVIII infusions prophylactically or symptomatically.

Question 11

What is shock and its main types?

Answer 11

Circulatory failure causing tissue hypoxia; hypovolemic (hemorrhage, burns), cardiogenic/obstructive (MI, arrhythmia, embolism), distributive (sepsis/SIRS, anaphylaxis).