Wound Healing And Clotting Cascade

Front 1

What are the three main phases of Wound Healing?

Back 1

Inflammation, Repair & Remodeling

Front 2

Define the term “wound”

Back 2

Disruption of continuity of the skin

Front 3

What happens immediately following wounding?

Back 3

Haemostasis

Front 4

What are the 3 phases of Haemostasis?

Back 4

Vasoconstriction, Platelet Plug formation, Blood Clotting

Front 5

What function causes vasoconstriction?

Back 5

Smooth muscle contraction

Front 6

Name 3 stimulants of Smooth Muscle contraction

Back 6

Myogenic Spasm, Nervous stimulation, Tissue & Platelet factors (e.g. Serotonin & Thromboxane A2)

Front 7

From which cell lineage are platelets derived?

Back 7

Megakaryocyte lineage of Myeloid Progenitor

Front 8

What causes the binding of platelets?

Back 8

Exposure of Collagen/ Von Willebrand factor

Front 9

What happens to platelets once they have bound to injured site?

Back 9

They become activated and begin to secrete the contents of their granules

Front 10

What is contained within the granules of platelets?

Back 10

ADP, Thromboxane A2, Serotonin.

Front 11

What causes the agglutination of additional platelets to a wound site, and hence causes the formation of a platelet plug?

Back 11

ADP & Thromboxane A2 as they cause platelets to become “sticky”

Front 12

The initial platelet plug is fairly unstable. What happens to stabilize this plug?

Back 12

Production of long fibrin fibres that form a meshwork in the plug to trap blood cells, platelets and plasma.

Front 13

How long does it take for blood coagulation to begin to occur?

Back 13

1-2mins

Front 14

What are the main pathways of the Clotting Cascade?

Back 14

Intrinsic (Platelet Derived) & Extrinsic (Tissue Trauma Derived)

Front 15

What is the first step of the Clotting Cascade?

Back 15

Formation of Prothrombin Activator (Factor X)

Front 16

Describe the steps in the Intrinsic formation of Prothrombin Activator

Back 16

Factor XII → Factor XIIa; Factor XIIa turns Factor XI → Factor XIa; Factor XIa turns Factor IX → Factor IXa; (Thrombin (IIa) turns Factor VIII → Factor VIIIa); Factor VIIIa + Factor IXa turns Factor X → Factor Xa(Prothrombin Activator)

Front 17

Describe the steps in the Extrinsic formation of Prothrombin Activator

Back 17

Factor VII → Factor VIIa; Factor VIIa turns Factor X → Factor Xa

Front 18

What factor acts in conjunction with Factor Xa to activate Prothrombin(II)?

Back 18

Factor Va

Front 19

What does Thrombin(IIa) activate?

Back 19

Factor VIII, V and Fibrinogen(I)

Front 20

What effect does Factor XIII have on Fibrin(Ia)?

Back 20

Stabilises by causing crosslinking

Front 21

What is responsible for fibrolysis (clot lysis)?

Back 21

Plasmin

Front 22

What turns plasminogen → plasmin?

Back 22

Factor Xa & Va + Urokinase

Front 23

What does the clot do to reduce wound size after 20-60 mins?

Back 23

Contracts, forcing out trapped plasma

Front 24

What ion is essential for many steps of the Clotting Cascade?

Back 24

Ca2+

Front 25

Name the Cardinal Signs of Inflammation

Back 25

Heat(Calor), Pain(Dolor), Swelling (Tumor), Redness (Rubor), Loss of Function (Functio Laesa)

Front 26

What substances cause many of the cardinal signs?

Back 26

Inflammatory Mediators such as: Histamine, Serotonin, Bradykinins, Prostaglandins, Cytokines, Interleukins & Leukotrienes

Front 27

Name the two parts of the repair phase of wound healing

Back 27

Neovascularisation(Angiogenesis) & Proliferation

Front 28

What cells proliferate to provide replacement cells for wound healing?

Back 28

Cells in the stratum basale + fibroblasts

Front 29

What do fibroblasts produce initially to fill the wound site?

Back 29

Collagen III

Front 30

What migrates to wound site during proliferation?

Back 30

Existing cells, peripheral to the wound

Front 31

What stimulates Angiogenesis?

Back 31

Chemotactic factors produced by immune cells exposed to hypoxic conditions

Front 32

Why does Angiogenesis cease?

Back 32

When blood supply is restored, oxygen levels are restored to normal, hence, immune cells stop producing the chemotactic factors that stimulate angiogenesis

Front 33

How do stem cells from uninjured parts of blood vessels push through the ECM to form new blood vessels?

Back 33

Pseudopodia projections develop to push through the ECM

Front 34

Granulation tissue is deposited at the proliferation stage. What does this consist of?

Back 34

Vascularised Extra-cellular Matrix (ECM)

Front 35

Degradation of the surrounding ECM aids the Repair phase. What substances aid this degradation?

Back 35

Plasmin, Collagenases, other Proteinases

Front 36

What do fibroblasts differentiate into approx. 1 week after wounding?

Back 36

Myofibroblasts

Front 37

What is the function of Myofibroblasts?

Back 37

Contractile actin fibres in these cells allow them to help to reduce the wound size & therefore reduce the formation of scar tissue after healing.

Front 38

What happens in the Remodeling phase of wound healing?

Back 38

Haphazard Collagen III is replaced by stronger Collagen I, arranged along the tension lines.

Front 39

Roughly how long does the Remodeling phase last for?

Back 39

6 months – 2 years

Front 40

How strong is the scarified tissue in relation to regular tissue?

Back 40

80% as strong

Front 41

What causes the eventual reduction in redness of the scarified tissue?

Back 41

Apoptosis of Blood Vessels