TISSUE REPAIR

Question 1

Two elements of tissue repair

Answer 1

1- regeneration
2- fibrosis

Question 2

fibrosis

Answer 2

scarring resulting from chronic inflammation that provides enough structural stability to allow the tissue to mostly
- is only capable of restoring STRUCTURE, not function

Question 3

Regeneration

Answer 3

proliferation of cells that survive the injury and retain the capacity to generate the mature cells of that tissue
- may be mature differentiated cells or more commonly tissue stem cells

Question 4

Scar formation

Answer 4

repair that occurs by the laying down of connective (fibrous) tissue

Question 5

Labile cells

Answer 5

continuously dividing cells always in the cell cycle
- ie surface epithelia

Question 6

Stable cells

Answer 6

infrequently dividing cells
- are normally quiescent unless needed
- i.e liver cells, smooth muscle cells, vascular endothelium

Question 7

Permanent cells

Answer 7

rarely or non-dividing cells
-i.e neurons, cardiac and skeletal muscle
- is the hardest to regenerate

Question 8

Anti-Ki-67

Answer 8

antibody stain that marks cells in late G1, S and G2 phases of the cell cycle

Question 9

basal cells

Answer 9

stem cells capable of regenerating itself and more differentiated cells
- these cells are always in the cell cycle

Question 10

Characteristics of Cirrhotic Liver

Answer 10

histological: hepatic lobule with reduced amount hepatocytes, blood vessels compressed by surrounding collagen deposits
anatomical : liver appears enlarged with a nodular/bumpy appearance
functional: liver failure

Question 11

Characteristics of Pulmonary Fibrosis

Answer 11

histological: significantly reduced space between alveoli, dense interstitial and peribronchial fibrosis
anatomical: lungs have honeycomb appearance
functional: total respiratory failure

Question 12

Chronic peptic ulcer

Answer 12

histological: collagenous deposits interrupting muscle layer, break in epithelia
anatomical: sore-looking interruption in mucosal wall, loss of folds of stomach that allow distention
functional: acid reflux, gastric pain

Question 13

Steps of tissue repair in Chronic peptic ulcer

Answer 13

1- inflammation
2- cell proliferation and migration
3- synthesis of extracellular matrix
4- remodeling of extracellular matrix

Question 14

myeloperoxidase

Answer 14

main enzymatic component of neutrophilic granules with anti-microbial properties

Question 15

MSA stain

Answer 15

stains for smooth muscle cells

Question 16

Granulation tissue

Answer 16

characterized by proliferation of fibroblasts and thin-walled, delicate capillaries in a loose extracellular matrix, often with admixed inflammatory cells, mainly macrophages
- is progressively deposited at the site of injury; the amount of granulation tissue that is formed depends on the size of the tissue deficit created by the wound and the intensity of inflammation

Question 17

Which method of cell signaling do tumor cells favor and why?

Answer 17

autocrine
this tends to be the most uncontrollable because the cell releases molecules that feed back onto itself

Question 18

Elements of inflammation

Answer 18

goal: to confine the trauma and start tissue repair process
cellular: fibrin, neutrophils, macrophages, platelets
molecular: cytokines, growth factors

Question 19

Elements of cell proliferation and migration

Answer 19

goal: to promote cell proliferation and granulation tissue
cellular: fibroblasts, macrophages, endothelial cells/capillaries
molecular: growth factors, angiopoietins
- i.e edematous fluid as body is trying to rapidly deliver nutrients to the affected area

Question 20

Extracellular matrix

Answer 20

serves to fill in the space acting as an anchor for supporting cellular structures providing turgor, elasticity and rigidity
- also serves as a reservoir for growth factors and is critical for cell adherence and migration

Question 21

2 domains of ECM

Answer 21

basal membrane and interstitial matrix

Question 22

basal membrane

Answer 22

produced by epithelial and mesenchymal cells to form a ribbonlike structure that allows epithelial cells to adhere and migrate

Question 23

interstitial matrix

Answer 23

fills in the space between cells and is the predominant element in connective tissue

Question 24

3 elements of ECM

Answer 24

1- fibrous structural proteins (collagens, elastins)
2- cell adhesion molecules/proteins (integrins, cadherins)
3- ECM gel (proteoglycans, hyaluronan

Question 25

Integrins

Answer 25

transmembrane glycoproteins that mediate the adhesion of leukocytes to endothelium and of various cells to the extracellular matrix/basement membrane - sit along plasma membrane and do not bind their ligands until leukocyte activation by chemokines

Question 26

Fibronectin

Answer 26

large glycoprotein produced by fibroblasts, endothelial cells and monocytes - provides a scaffold for subsequent ECM deposition, angiogenesis, and regenerated epithelia in wound healing

Question 27

Laminin

Answer 27

most abundant glycoprotein in the basement membrane that links specific receptors to type IV collagen and heparan sulfate - modulates cell proliferation, differentiation, and motility

Question 28

Proteoglycans

Answer 28

core proteins linked to disaccharides that regulate ECM structure and permeability - form highly hydrated gels that confer resistance to compressive forces - also provide a layer of lubrication between adjacent bony surfaces - also serve as reservoirs for secreted growth factors - i.e heparan sulfate, chondroitin sulfate

Question 29

Hyaluronan

Answer 29

large molecules of repeating disaccharides that bind water to give tissues turgor pressure

Question 30

Elements of ECM remodeling

Answer 30

done by degradation of collagen and other ECM proteins by metalloproteinases and formation of collagen plates along the lines of physical stress - degradation of unnecessary structural proteins in an organized way for increased stability

Question 31

Examples of matrix metalloproteinases (MMPs)

Answer 31

collagenases, gelatinases, stromelysins

Question 32

Most significant event of wound healing?

Answer 32

collagen accumulation and remodeling

Question 33

Healing by first intention

Answer 33

healing by primary union that occurs when wounds are closed physically with sutures, metal staples, dermal adhesive, etc

Question 34

Healing by second intention

Answer 34

healing by secondary union that occurs when wounds are allowed to heal by wound contraction and is mediated by myofibroblasts at the edge of the wound - involves more extensive scarring and wound contraction from increased myofibroblast proliferaton

Question 35

Local factors that affect wound healing

Answer 35

blood supply, denervation, infection, foreign body, mechanical stress, necrotic tissue, surgical technique, tissue type

Question 36

Systemic factors that affect wound healing

Answer 36

chronic diseases/deficiencies - i.e diabetes, malnutrition

Question 37

Hypertrophic scar

Answer 37

results in a prominent scar that is localized to the wound, due to excess production of granulation tissue and collagen (insufficient ECM remodeling) - common of burn patients