Haemostasis

Question 1

What is haemostasis?

Answer 1

Haemostasis is the arrest of bleeding from a broken blood vessel (‘Hemo’ = blood / ‘stasis’ = standing)

Question 2

What are the four stages of acute wound healing?

Answer 2

1) Haemostasis
2) Inflammatory phase
3) Proliferative phase
4) Remodelling

Question 3

What is the time frame for haemostasis?

Answer 3

Seconds to hours

Question 4

What is the time frame for the inflammatory phase?

Answer 4

Hours to days

Question 5

What is the time frame for the proliferative phase?

Answer 5

Days to Week

Question 6

What is the time frame for the remodelling phase?

Answer 6

Week to Months

Question 7

What happens during haemostasis during acute wound healing?

Answer 7

Vasoconstriction
Platelet aggregation
Leucocyte migration

Question 8

What happens during the inflammatory phase of acute wound healing?

Answer 8

Early neutrophils
Chemoattractant release
Late macrophages
Phagocytosis and removal of foreign body/ bacteria

Question 9

What happens during the proliferative phase of acute wound healing?

Answer 9

Fibroblast proliferation
Collagen synthesis 
Extracellular matrix (ECM) reorganisation
Angiogenesis
Granulation tissue formation
Epithelialization

Question 10

What is epithelialization?

Answer 10

Epithelization is characterized by replication and migration of epithelial cells across the skin edges in response to growth factors.

Question 11

What is angiogenesis?

Answer 11

Angiogenesis is the formation of new blood vessels. This process involves the migration, growth, and differentiation of endothelial cells, which line the inside wall of blood vessels. The process of angiogenesis is controlled by chemical signals in the body.

Question 12

What happens during the remodelling phase of acute wound healing?

Answer 12

Remodelling
Epithelialization
ECM remodelling
Increase in tensile strength of the wound

Question 13

What are the three major steps in Haemostasis?

Answer 13

1) Vascular Spasm - blood vessels contract allowing less blood to be lost
2) Formation of platelet plug - platelets stick together to form a temporary seal to cover the break in the vessel wall
3) Conversion to a clot by reinforcement with fibrin

Question 14

What happens if too much haemostasis occurs?

Answer 14

Thrombus formation

Question 15

What happens if there is too little haemostasis occurring?

Answer 15

Excessive bleeding

Question 16

What factors are released when platelets become activated and what is the function of these factors?

Answer 16

ADP - (adenosine 5’-diphosphate) sticky platelets
Serotonin - vasoconstriction
Thromboxane A2 - Vasoconstricts and activates

Question 17

What happens when these factors are released into the surrounding area?

Answer 17

Vasoconstriction and activation of more platelets - positive feedback

Question 18

What activates the intrinsic pathway of the coagulation cascade?

Answer 18

Damaged surface

Question 19

What activates the extrinsic pathway of the coagulation cascade?

Answer 19

Trauma

Question 20

How long does it take for plasmin trapped in the clot to break down fibrin into double fragments?

Answer 20

One week

Question 21

How does a clot retract and dissolve?

Answer 21

The enzyme plasmin trapped in the clot acts on fibrin to break it down into soluble fragments

Question 22

For which clotting factors does vitamin K act as a coenzyme for their synthesis?

Answer 22

II, VII, IX, X

Question 23

What drug thins the blood and prevents clotting?

Answer 23

Warfarin or Dabigatran

Question 24

What is the role of the liver in clotting?

Answer 24

1) Synthesizes clotting factors
2) Synthesizes bile salts - These bile salts in the bile cause the absorption of vitamin K in the GI tract allowing vitamin K to be absorbed into the blood. Vitamin K then post-translationally modifies synthesised clotting factors.

Question 25

What is coagulopathy?

Answer 25

Coagulopathy (also called a bleeding disorder) is a condition in which the blood’s ability to coagulate (form clots) is impaired. This condition can cause a tendency toward prolonged or excessive bleeding (bleeding diathesis), which may occur spontaneously or following an injury or medical and dental procedures.

Question 26

What is von Willebrand disease?

Answer 26

A disease which causes a defect or deficiency in von Willebrand factor, meaning it takes longer for the blood to clot.

Question 27

What is septic shock?

Answer 27

Septic shock is a severe and potentially fatal condition that occurs when sepsis leads to life-threatening low blood pressure. Sepsis develops when the body has an overwhelming response to infection.