Tissue Renewal and Repair

Question 1

What is parenchyma?

Answer 1

Functional cellular components of the tissue or organ

Question 2

What is scarring?

Answer 2

Replacement of epithelium/parenchyma with CT

Question 3

What is the bodies two responses to tissue loss?

Answer 3

Repair by regeneration or scarring

Question 4

What is fibrosis?

Answer 4

An abnormal deposit of collagen and other ECM in the process of repair

Question 5

What happens in a deep skin wound?

Answer 5

Stromal cells proliferate and predominate the parenchymal cells

Question 6

When can regeneration occur?

Answer 6

As long as parenchyma can still proliferate and sufficient stromal tissue can provide support

Question 7

What can chronic inflammation cause?

Answer 7

Fibrosis due to periodic cell loss

Question 8

What are the primary inflammatory cells?

Answer 8

Polymorphonucleocytes (neutrophils) macrophages

Question 9

What is granulation tissue?

Answer 9

Initial phase of stromal repair response highly vascular loose CT

Question 10

What are three types of tissues?

Answer 10

Labile
Stabile
Permanent

Question 11

What are labile tissues?

Answer 11

Continuously dividing cells

Question 12

What are stabile tissues?

Answer 12

Quiescent cells that are in the Go stage and have limited proliferation can be stimulated to enter G1 stage

Question 13

What are permanent tissues?

Answer 13

Post-mitotic cells

Question 14

What are the 8 processes of wound healing/repair?

Answer 14

Maintain hemostasis
Inflammatory response
Proliferation and migration of parenchyma cells
Angiogenesis
Formation of granulation tissue
Connective tissue remodeling
Wound contraction
Acquisition of increasing wound strength

Question 15

What is needed for hemostasis?

Answer 15

Fibrinogen->Fibrin (scab/eschar formation)

Question 16

What is provisional matrix?

Answer 16

Temporary loose CT

Type III collagen

Question 17

What is involved in granulation tissue?

Answer 17

Angiogenesis
Mononuclear inflammatory cells
Type III collagen

Question 18

What are matrix metalloproteinases (MMPs)?

Answer 18

Enzymes that help degrade extracellular proteins

Question 19

How is the ECM remodeled?

Answer 19

Activation of MMPs and signaling of fibroblasts to deposit new proteins

Question 20

What signals the activation of fibroblasts?

Answer 20

TGF-Beta

Question 21

What causes wound contraction?

Answer 21

Myofibroblasts

Question 22

How is wound tensile strength increased?

Answer 22

Type 1 collagen (mature scar) is laid down

Question 23

What is granulation tissue as apposed to fibrosis?

Answer 23

Immature scar vs a mature scar

Question 24

What is healing by primary intent?

Answer 24

Approximating the wound edges to minimize scarring and heal quickly; typically not as deep of a wound

Question 25

What is healing by secondary intent?

Answer 25

Allowing the wound to heal by granulomatous tissue; grows from the bottom up and will leave a scar healing slowly; typically deep wounds

Question 26

What is patchy loss of cells in the heart cause?

Answer 26

Interstitial fibrosis

Question 27

What does diffuse loss of cells in the heart cause?

Answer 27

Myocardial infarction

Question 28

How long does it take for granulation tissue to mature?

Answer 28

7 days

Question 29

When does a scar gain maximum tensile strength?

Answer 29

14-21 days

Question 30

What can occur with 14 days of a MI?

Answer 30

An aneurysm may form due to weak scar formation if enough pressure is applied

Question 31

What is the difference between PNS and CNS axons?

Answer 31

CNS axons cannot regenerate | PNS axons can elongate and regenerate

Question 32

What accomplishes scarring in the CNS?

Answer 32

Glial cells via gliosis

Question 33

What accomplishes scarring in the PNS?

Answer 33

Fibroblasts via fibrosis

Question 34

What is hypertrophic scarring?

Answer 34

Excessive scar formation due to excessive amounts of collage resulting in a raised scar?

Question 35

What is a keloid?

Answer 35

Disorganized excessive scarring; excessive collagen in dermis that overshoots the bounds of the injury

Question 36

What is contracture?

Answer 36

Deformity of wounded tissue and surrounding structures

Question 37

How can contracture occur in somatic and visceral body parts?

Answer 37

Somatic: where skin is too close to tendons the tendons can become caught in contracting wounds Visceral: can cause bowel strictures/obstruction

Question 38

What collagen is found in a mature scar?

Answer 38

Type I collagen

Question 39

What is a pyrogenic granuloma?

Answer 39

Inflammatory lesion with exuberant overgrowth of granulation tissue; neoplastic (often in gingiva of pregnant women)

Question 40

What is proud flesh?

Answer 40

Granulation of tissue that extends above the epithelial surface and inhibits re-epithelialization

Question 41

What is a desmoid?

Answer 41

Fibrosis following injury or surgical incision within soft tissue (neoplastic)