Coagulation Cascade

Question 1

Define Coagulation cascade
- aka Secondary Hemostasis

Answer 1

• A series of steps in response to bleeding caused by tissue injury, where each step activates the next & ultimately produces a blood clot.

Question 2

Define Hemostasis

Answer 2

• process of preventing or stopping bleeding.

Question 3

3 Pathways of Coagulation

Answer 3

1. Extrinsic
2. Intrinsic
3. Common

Question 4

Clotting factors

Answer 4

• proteins that are involved in blood clotting.
• a serine protease = an enzyme that speeds up the breakdown of another protein.

Question 5

Clotting factors are initially in an…

Answer 5

inactive form called zymogens.

Question 6

Zymogens

Answer 6

• inactive form of clotting factors

Question 7

Clotting factors become activated when…

Answer 7

placed with its glycoprotein co-factor.

Question 8

What does Factor Va mean?

Answer 8

• means that the clotting factor V has become activated.
• an a represents activation

Question 9

Extrinsic Pathway - clotting factors

Answer 9

• involves initiation by factor III (i.e., tissue factor) and its interaction with factor VII.

Question 10

Intrinsic Pathway - clotting factors

Answer 10

• Factor XII, XI, IX & VIII

Question 11

Common Pathway - clotting factors

Answer 11

• Factors X, V, II, I, & XIII.

Question 12

Hemostasis is divided into…

Answer 12

• Primary hemostasis
• Secondary hemostasis

Question 13

5 Mechanisms of Hemostasis

Answer 13

1. Vascular Spasm
2. Platelet Plug Formation (primary hemostasis)
3. Coagulation (secondary hemostasis)
4. Clot retraction & repair
5. Fibrinolysis

Question 14

Purpose of Hemostasis

Answer 14

• facilitates a series of enzymatic activations that lead to the formation of a clot with platelets & fibrin polymer. This clot seals the injured area, controls and prevents further bleeding while the tissue regeneration process takes place. Once the injury starts to heal, the plug slowly remodels, and it dissolves with the restoration of normal tissue at the site of the damage.

Question 15

Vascular spasm

Answer 15

• when a blood vessel is damaged or punctured, vascular spasm occurs.
• this is when the smooth muscle in the walls of the vessel contract dramatically.
• it is triggered by endothelins which are released by endothelial cells & by pain receptors in response to vessel injury.

Question 16

Platelet Plug Formation (primary hemostasis)

Answer 16

• platelets (normally float free in the plasma) encounter the area of vessel rupture with the exposed underlying connective tissue & collagenous fibers & begin to clump together, become spiked & sticky, & bind to the exposed collagen & endothelial lining.
• this process is assisted by von Willebrand factor = glycoprotein that helps to stabilize the growing platelet plug.
• as platelets collect, they simultaneously release chemicals from their granules into the plasma that further contribute to hemostasis:
  1. Adenosine diphosphate (ADP) = helps additional platelets to adhere to the injury site, reinforcing & expanding the platelet plug.
  2. Serotonin = maintains vasoconstriction
  3. Prostaglandins & Phospholipids = maintains vasoconstriction & help to activate further clotting chemicals.

Question 17

Coagulation