Biochem3.tissue Repair Lecture.mcv

Front 1

Which cells are the first to arrive at the site of a wound?

Back 1

Platelets and inflammatory cells are the first to arrive at the wound site.

They provide signal growth factors (cytokines) for the influx of connective tissue and blood.

Front 2

What happens when too much collagen is deposited in the wound site? Too little?

Back 2

Too much collagen leads to:
1. loss of normal anatomical structure
2. compromised function
3. fibrosis (development of excess fibrous connective tissue)

Too little collagen can lead to:
1. dehisces of wound

Front 3

Define the following:

-Wound
-Healing

Back 3

Wound - a disruption of normal anatomic structure and function

Healing - complex and dynamic process resulting in restoration of anatomically continuity and function

Front 4

Define the following:

-Acute Wound
-Chronic Wound

Back 4

Acute Wound - orderly/timely repair resulting in sustained restoration of anatomy/function

Chronic Wound - failed orderly/timely process to restore anatomy/function, OR proceeded through repair WITHOUT establishing anatomy/functionality

Front 5

Responses of tissue to injury:

1. Resolution

2. Regeneration

3. Repair by Scar

Back 5

1. Resolution - follows minimal tissue injury and inflammation. FULL repair

2. Regeneration - follows LOSS of tissue. FULL repair

3. Repair by Scar - follows injury and inflammation. Fibroblast proliferation and connective tissue elements.

Front 6

Pathologic responses of tissue to injury:

1. Fibrosis

2. Dehiscence

3. Contracture

Back 6

1. Fibrosis - follows injury and inflammation. Replacement involves distorted accumulation of scar tissue. Function is LOST.

2. Dehiscence - during scar repair, low/unstable collagen. Wound will split when tension is applied.

3. Contracture - excessive scar contraction leads to malformation and loss of movement (burn injuries). Caused by specialized myofibroblasts (hybrid fibroblasts and smooth muscle cells)

Front 7

Mechanisms of wound repair:

1. Connective tissue deposition

2. Epithelization

3. Contraction

Back 7

1. Connective tissue deposition - fibroblasts proliferation at wound site, produces collagen and proteoglycans

2. Epithelization - epithelial cells and hair follicles migrate across wound surface and proliferate to form new epithelial surface.

3. Contraction - normal process, wound margins pulled towards center via myofibroblasts. Contracture = excessive contraction

Front 8

Clinical techniques for wound closure:

1. Primary Intention

2. Delayed primary intention

3. Secondary Intention

4. Partial Thickness Healing

Back 8

1. Primary intention - matrix deposition

2. Delayed primary intention - wound is contaminated [...] same as primary

3. Secondary Intention - mainly contraction, also involves matrix deposition and epithelization.

4. Partial thickness healing - ALL epithelization.

Front 9

What are the initial response factors following tissue injury?

Back 9

1. Fibrin clot formation - initial wound matrix and guides inflammatory cells and fibroblasts

2. Platelets. PDGF and TGFbeta
TGFbeta
-increase collagen
-decrease MMP
-increase TIMP

Front 10

After platelets release their coagulatoin factors and cytokines what happens?

Back 10

PMN prevent wound infections
a) vessel adherence
b) diapedesis - squeeze through vessel walls
c) chemotaxis - directed movement
d) phagocytosis (opsonization) - eat the bacteria

Front 11

What is the most essential type of inflammatory cell and how is it activated?

Back 11

Macrophages!
a) Interleukin-1 signals fibroblast proliferation
b) TFGbeta
c) PDGF
d) Tumor necrosis factor (cachectin, TNF) also for fibroblast proliferation

Front 12

What do the Mast cells release?

Back 12

Gives off mediators which produce redness and itchiness around a wound.
a) vasoactive amines - histamine and serotonin
b) heparin
c) proteolytic enzymes
d) prostoglandins, leukotrienes, thromboxanes
e) TNF

Front 13

What to Lymphocytes release?

Back 13

a) TGFbeta
b) TNF

Front 14

What are the four characteristics of wound inflammation mediated by mast cells?

Back 14

1. Redness (Rubor)

2. Swelling (Tumor)

3. Heat (Calor)

4. Pain (Dolor)

Front 15

What is the one factor that is the most important reason for delayed healing?

Back 15

INFECTION. Treat with gentle irrigation. Balance the good with bad.

Front 16

Do leukocytes operate in arteries or veins?

Back 16

Veins!