7 Haemostasis, Fibrinolysis and Wound Repair

Question 1

Haemostasis

Answer 1

Blood coagulation and prevention of blood loss

coagulation = clotting

Question 2

Coagulation cascade

Answer 2

Factors
Mechanisms
Inhibitors

Question 3

stages of wound repair

Answer 3

1. Haemostasis
2. Coagulation cascade
3. Fibrinolytic cascade
4. Wound repair§

Question 4

Fibrinolysis

Answer 4

removal of clots, prevention of clotting

Question 5

what is haemostasis needed for

Answer 5

1. Mechanism is needed to reduce blood loss after vascular injury - prevention of bleeding
2. Blood must also remain fluid during normal function - prevention of coagulation (thrombosis)

Question 6

what does haemostasis require

Answer 6

• Requires a balance of haemostatic and fibrinolytic processes

Question 7

what does haemostasis result in

Answer 7

Results in great complexity

Question 8

why are haemostasis of great medical interests

Answer 8

• Prevention of blood loss
• Wound repair and recovery from surgery
• Prevention of circulatory disease (anticoagulants, antithrombotics and “clot busters”)

Question 9

Haemostasis: Sequence of events

Answer 9

1. Injury, involving vascular damage
2. Inflammation (Triple response) exudate
3. immune response

Question 10

what does coagulation generate

Answer 10

Generation of a thrombus (clot) at a site of vascular injury

Question 11

Thrombus

Answer 11

fibrin plug + platelets

Question 12

what does thrombus limit

Answer 12

blood loss

Question 13

what does thrombus initiate

Answer 13

tissue repair

fibrinolysis

Question 14

where is fibrinogen synthesised

Answer 14

liver

Question 15

where is fibrinogen

Answer 15

Constantly present in blood

Question 16

what is thrombin

Answer 16

• Enzyme

- Active form of prothrombin

Question 17

when is thrombin formed

Answer 17

Final element of coagulation cascade

Question 18

Coagulation: fibrin

Answer 18

formed by polymerisation of fibrinogen

Question 19

fibrin in solution

Answer 19

Too large to remain in solution

Question 20

what stabilises fibrin

Answer 20

Stabilised by Fibrinoligase (Factor XIII)

Question 21

what does fibrin bind

Answer 21

• Binds platelets
• Binds fibronectin
• Binds fibrinolytic factors

Question 22

Factors II, VII, IX, X

Answer 22

Group of similar molecules, arising from gene duplication

Question 23

what do factors II, VII, IX, X need for synthesis in liver

Answer 23

Synthesis by liver requires vitamin K

Question 24

what are factors II, VII, IX, X

Answer 24

Some slow-acting anticoagulants work by antagonising Vitamin K in liver

Question 25

what do Factors II, VII, IX, X lead to

Answer 25

progressive haemophilia and eventual death

Question 26

what are Factors II, VII, IX, X useful for

Answer 26

anti-thrombotics in human medicine

Question 27

Factor VIII

Answer 27

Antihaemophilic globulin

Question 28

Inability to synthesise Factor VIII

Answer 28

Haemophilia

Question 29

what is Haemophilia

Answer 29

Hereditary disorder | Inability to control bleeding, often from minor injuries to skin or gut

Question 30

who expresses haemophilia

Answer 30

Expressed in males only: X-linked recessive gene (carrier females may have lower Factor VIII but are asymptomatic)

Question 31

Von Willebrand factor importance

Answer 31

Not strictly part of the coagulation cascade but important to coagulation

Question 32

where is Von Willebrand factor

Answer 32

Circulates in plasma bound to Factor VIII

Question 33

Von Willebrand factor effect

Answer 33

Stabilises Factor VIII and extends its half-life. Factor VIII ineffective in absence of vWF

Question 34

what does Von Willebrand factor enhance

Answer 34

platelet binding to damaged tissue

Question 35

Fibronlysis

Answer 35

Breakdown of thrombus and initiation of wound repair | Degradation of Fibrin by Plasmin

Question 36

Re-epithelialization

Answer 36

Resurfacing of the wound site: Regrowth of epithelium

Question 37

where is re-epithelialization

Answer 37

Sweat glands, hair follicles and nerves reform, except in scar tissue

Question 38

ECM remodelling and scar tissue - collagen types

Answer 38

Collagen Type III | Collagen Type I

Question 39

Collagen Type III

Answer 39

rapidly produced, short strands, limited strength

Question 40

what is collagen type III replaced by

Answer 40

Collagen Type I

Question 41

Collagen Type I

Answer 41

slowly produced, long strands, greater strength