Tissue Repair and Wound Healing

Question 1

What does regeneration of tissue require?

Answer 1

intact ECM

note: seen in tissues with high proliferative activity

Question 2

Repair can be defined as a combination of regeneration and scar formation by ____ deposition

Answer 2

collagen

Question 3

Tissue is dividing into three groups according to proliferative activity. Differentiate the following three groups and note where they are found:
continously dividing (labile) cells
quiescent (stable) cells
non-dividng (permanent) cells

Answer 3

continously dividing (labile) cells: proliferate throughout life; found in bone marrow, epidermis

quiescent (stable) cells: normally involved in low-level replication but may respond to stimuli by rapid division; found in liver, fibroblasts, kidney, smooth muscle

non-dividng (permanent) cells: do not undergo division in post-natal life; found in neurons, cardiac myocytes

Question 4

This type of stem cell arises from the inner cell mass of blastocysts and is pluripotent

Answer 4

embryonic stem cells

Question 5

This type of stem cell is identified in many mature tissues. It is more limited in its ability to differentiate

Answer 5

adult stem cells

Question 6

The ECM is vital to tissue regeneration, it sequesters ___ and provides ___ to soft tissues and minerals for bone

Answer 6

water; turgor

Question 7

What are the two fibrous structural proteins of ECM

Answer 7

collagens - tensile strenght

elastins - recoil

Question 8

This component of the ECM connects components to one another and to cells; mostly transmembrane receptors
ex: Ig family, interns, selecting, cadherins

Answer 8

Adhesive glycoproteins (CAMs)

Question 9

These components of the ECM are responsible for resilience and lubrication

Answer 9

proteoglycans and glycosaminoglycans

Question 10

Tissue injury resulting in damage of ____ and ___ elements cannot heal by regeneration, but instead by repairing and scarring

Answer 10

parenchyma; stromal

Question 11

Describe the sequence of healing

Answer 11

1. inflammation
2. angiogenesis
3. migration and proliferation of fibroblasts
4. scar formation
5. CT remodeling

Question 12

Within ___ hours of clot formation, neutrophils appear; use scaffolding of clot to “move in” and clean up the mess

Answer 12

24

Question 13

Proliferation of fibroblasts and vascular endothelium starts in ____-____ days

Answer 13

1-3

Question 14

What are histologic features of granulation tissue formation?

Answer 14

small new blood vessels due to angiogenesis, proliferation of fibroblasts, vessels are leaky - tissue is edematous

Question 15

Granulation tissue peaks around __-__ days

Answer 15

5-7

Question 16

Neutrophils are largely replaced by ____ by 2-4 days

Answer 16

macrophages

Question 17

What do macrophages do in the tissue repair process?

Answer 17

clear debris; promote angiogenesis and ECM deposition, main source of growth factors

Question 18

In regards to scar formation, how long does it take for leukocytes and granulation tissue to have mainly disappeared

Answer 18

2 weeks

Question 19

In regards to scar formation, describe blanching (occurs after leukocytes and granulation tissue has disappeared)

Answer 19

increased collagen within wound; regression of vascular channels

Question 20

By the end of the ____ ____, the scar is composed of acellular CT, without inflammation, covered by intact epidermis

Answer 20

first month

Question 21

What causes wound contraction?

Answer 21

myofibroblasts, formed from tissue fibroblasts though effects of growth factors are similar to smooth muscle cells and contract in the wound tissue

Question 22

What is the benefit of wound contraction?

Answer 22

helps close gap by decreasing distance between dermal edges

Question 23

This is the single most important cause of delayed wound healing

Answer 23

infection

Question 24

This is an inadequate formation of granulation tissue or defective assembly of a scar

Answer 24

wound dehiscence or ulceration

Question 25

This is excessive formation of components of repair process

Answer 25

keloid or hypertrophic scar

Question 26

Exuberant granulation which blocks re-epithelization

Answer 26

proud flesh

Question 27

Exuberant fibroblast proliferation and other CT elements

Answer 27

desmoids or aggressive fibromatoses