[P] Week 2: Inflammation and Repair - Part 3

Question 2

TISSUE REPAIR

What is repair in the context of tissue?

Answer 2

Repair, also called healing, refers to the restoration of tissue architecture and function after an injury.

Question 3

TISSUE REPAIR

What initiates the healing process after tissue injury?

Answer 3

Injury to cells and tissues sets in motion a series of events that contain the damage and initiate the healing process.

Question 4

TISSUE REPAIR

What are the two processes involved in the repair of damaged tissues?

Answer 4

regeneration, which restores normal cells, and scarring, the deposition of connective tissue.

Question 5

TISSUE REPAIR

What factors influence the repair process?

Answer 5

The repair process depends on type of wound, inflammatory process, matrix damage, and organ.

Question 6

CELL AND TISSUE REGENERATIO

What is complete healing of an organ?

Answer 6

It is a complete healing of the organ (ex. wound, injury)

Example: Healing of a cut on the skin.

Question 7

CELL AND TISSUE REGENERATIO

What does regeneration involve?

Answer 7

Involves proliferation of cells and tissues.

Question 8

CELL AND TISSUE REGENERATIO

What is replaced during regeneration?

Answer 8

Replacement of structure and function.

Question 9

CELL AND TISSUE REGENERATIO

Which organs in the body may regenerate?

Answer 9

Liver, kidney, epithelia of skin and GIT.

Question 10

TISSUE PROLIFERATIVE ACTIVITY

Tissue of the body are divided into 3 groups on the basis of proliferative activity of their cells, enumerate

Answer 10

• Labile tissues (continuously dividing)
• Quiescent tissues (stable)
• Permanent tissues (non-dividing)

Question 11

TISSUE PROLIFERATIVE ACTIVITY

continuously dividing cells that proliferate throughout life, replacing those that are destroyed.

Answer 11

Labile tissues (continuously dividing

Examples include surface epithelia, squamous cells (skin, oral cavity, vagina, cervix), lining of excretory ducts, columnar epithelium (GIT, endometrium), and transitional epithelium (GUT).

Question 12

TISSUE PROLIFERATIVE ACTIVITY

Where are labile cells found?

Answer 12

Labile cells can be found in bone marrow and in hematopoietic tissues.

Question 13

TISSUE PROLIFERATIVE ACTIVITY

low level of replication but can undergo rapid division in response to stimuli, allowing them to reconstitute the tissue of origin.

Answer 13

Quiescent tissues (stable)

Examples include parenchymal cells (liver, kidneys, pancreas), fibroblasts, smooth muscle cells, chondrocytes, osteocytes, and endothelial cells.

Question 14

TISSUE PROLIFERATIVE ACTIVITY

lining epithelium of a blood vessel but are not labile cells; they proliferate only when there is an injury.

Answer 14

Endothelial cells

Question 15

TISSUE PROLIFERATIVE ACTIVITY

consist of cells that have left the cell cycle and cannot undergo mitotic division in postnatal life.

Answer 15

Permanent tissues (non-dividing

Examples include cardiac muscle, skeletal muscle, and neurons.

Question 16

MECHANISMS OF TISSUE & ORGAN REGENERATION

Mammals cannot regenerate whole tissues or organs because of the following reasons, enumerat

Answer 16

• No blastema formation
• Rapid fibroproliferative response after injury
• Wnt/β-catenin is highly conservative

Question 17

LIVER REGENERATION

TOF

The human liver has a remarkable capacity to explode.

Answer 17

F - regenerate

Question 18

LIVER REGENERATION

How is liver mass restored after resection?

Answer 18

Restoration of liver mass is achieved without the regrowth of the lost lobes that were resected.

more of a compensatory growth

Question 19

LIVER REGENERATION

What are the two major mechanisms of liver regeneration?

Answer 19

Regeneration of the liver occurs by:
- proliferation of remaining hepatocytes
- repopulation from progenitor cells

Question 20

LIVER REGENERATION

What triggers hepatocyte proliferation in the regenerating liver?

Answer 20

Hepatocyte proliferation is triggered by the combined actions of cytokines and polypeptide growth factors.

Question 21

Do all hepatocytes replicate during liver regeneration?

Answer 21

Almost all hepatocytes replicate during liver regeneration after partial hepatectomy.

Question 22

What happens if repair cannot be accomplished by regeneration alone?

Answer 22

Repair occurs by replacement of the injured cells with connective tissue, leading to the formation of a scar, or by a combination of regeneration of some residual cells and scar formation.

Question 23

Steps in repair

Answer 23

1. Scar formation and fibrosis
   o First, there is injury in the area. There may be bleeding and scab formation, followed by inflammation.
2. Inflammation
3. Angiogenesis
4. Migration and Proliferation of Fibroblasts
5. Scar Formation
6. Connective Tissue Remodeling

Question 24

process of new blood vessel development from existing vessels

Answer 24

ANGIOGENESIS

Question 25

what are the types of Angiogenesis

Answer 25

- Vasculogenesis - Angiogenesis or Neovasculrization

Question 26

# ANGIOGENESIS It is the formation of new blood vessels assembled during embryonic development.

Answer 26

Vasculogenesis ## Footnote They may start from cells like angioblasts or hemangioblasts.

Question 27

# ANGIOGENESIS Vasculogenesis may start from?

Answer 27

angioblasts or hemangioblasts

Question 28

# ANGIOGENESIS It is the formation of new vessels in adults; these are already coming from a well-formed vessel and may appear as **branching or extending**.

Answer 28

Angiogenesis or Neovascularization

Question 29

# ANGIOGENESIS stable cells; once they are needed, they can proliferate.

Answer 29

Endothelial cells ## Footnote Initially, endothelial cells are on a low level of replication, however, once needed, they will undergo replication.

Question 30

# MECHANISMS OF ANGIOGENESIS What initiates angiogenesis from endothelial precursor cells?

Answer 30

**The endothelial progenitor cells (EPC**) from bone marrow initiate angiogenesis. | EPCs are similar to angioblasts and hemangioblasts.

Question 31

# MECHANISMS OF ANGIOGENESIS It involves vasodilation, degradation of bone marrow, proliferation and migration of endothelial cells, maturation of endothelial cells, and recruitment of periendothelial cells.

Answer 31

From pre-existing cells

Question 32

# MECHANISMS OF ANGIOGENESIS What happens during angiogenesis in adults from pre-existing vessels?

Answer 32

undergo **vasodilation** and **degrade** the basement membrane to release endothelial cells that will subsequently proliferate.

Question 33

# MECHANISMS OF ANGIOGENESIS What occurs after the proliferation of endothelial cells in angiogenesis?

Answer 33

Once the vessels proliferate, **it will initialize the new vessel**; further, new periendothelial or perivascular structures will form.

Question 34

# GROWTH FACTORS AND RECEPTORS INVOLVED IN ANGIOGENESIS What is the most important growth factor involved in angiogenesis?

Answer 34

Vascular endothelial growth factor (VEGF)

Question 35

# GROWTH FACTORS AND RECEPTORS INVOLVED IN What induces VEGF?

Answer 35

induced by hypoxia, TGF-β, PDGF, and TGF-α.

Question 36

# GROWTH FACTORS AND RECEPTORS INVOLVED IN What are the functions of VEGF?

Answer 36

- Promote angiogenesis - Increase vascular permeability - Stimulate endothelial cell migration and proliferation

Question 37

# ECM REGULATES ANGIOGENESIS ECM proteins participate in vessel sprouting through interactions with ____ ____ in endothelial cells and by providing a scaffold for vessel growth.

Answer 37

integrin receptors

Question 38

# ECM REGULATES ANGIOGENESIS What role do integrins play in angiogenesis?

Answer 38

**formation** and **maintenance** of newly formed blood vessels.

Question 39

# ECM REGULATES ANGIOGENESIS degrade the ECM to permit remodeling and extension of the vascular tube.

Answer 39

matrix metalloproteinases (MMPs)

Question 40

# ECM REGULATES ANGIOGENESIS How do matricellular proteins affect angiogenesis?

Answer 40

**destabilize cell-matrix interactions,** promoting angiogenesis.

Question 41

# ECM REGULATES ANGIOGENESIS Proteinases, like ____ ____ cleave extracellular proteins, releasing matrix-bound growth factors.

Answer 41

Plasminogen activators

Question 42

# ECM REGULATES ANGIOGENESIS What is necessary for the stabilization of newly formed vessels for stabilization

Answer 42

**pericytes**, **smooth muscle cells**, and the **deposition of connective tissue.**

Question 43

# ECM REGULATES ANGIOGENESIS The newly formed vessels are fragile and need to be stabilized through the recruitment of pericytes and smooth muscles and by the deposition of ECM proteins— what are the ECM proteins

Answer 43

angiopoietin 1 and 2, PDGF, and TGF-β

Question 44

# CUTANEOUS WOUND HEALING What occurs initially in the inflammation phase of cutaneous wound healing?

Answer 44

**Clot formation**

Question 45

# CUTANEOUS WOUND HEALING What is the histologic hallmark of healing in the proliferation phase?

Answer 45

Granulation tissue formation

Question 46

# CUTANEOUS WOUND HEALING What are the components of granulation tissue?

Answer 46

- neovascularization - angiogenesis - proliferation of fibroblasts

Question 47

# CUTANEOUS WOUND HEALING What role does granulation tissue play in wound healing?

Answer 47

Granulation tissue provides a **provisional matrix** for healing.

Question 48

# CUTANEOUS WOUND HEALING What follows granulation tissue formation in the healing process?

Answer 48

**Collagen deposition** and **fibrosis**

Question 49

# HEALING OF SKIN WOUNDS When the injury involves only the epithelial layer, the principal mechanism of repair is epithelial regeneration,

Answer 49

Primary Union (Healing By 1st Intention

Question 50

# HEALING OF SKIN WOUNDS - Involves excisional wounds, like ulcer. Even if it is cleaned or sutured, there are still presence of large spaces, as compared to incisional wound. - Excisional wounds are associated with intense inflammatory reaction

Answer 50

Secondary union (Healing By 2nd Intention)

Question 51

# HEALING OF SKIN WOUNDS Excisional wounds are associated with?

Answer 51

intense inflammatory reactions

Question 52

# HEALING OF SKIN WOUNDS Why is inflammation more intense in excisional wounds?

Answer 52

due to **larger tissue defects** having greater volumes of necrotic debris, exudate, and fibrin that must be removed.

Question 53

# HEALING OF SKIN WOUNDS What is the consequence of large tissue defects?

Answer 53

Large defects have a greater potential for secondary, inflammation-mediated injury.

Question 54

# HEALING OF SKIN WOUNDS What happens to granulation tissue in secondary union?

Answer 54

Much larger amounts of granulation tissue are formed to fill the bigger gap caused by the larger area of deficit.

Question 55

# HEALING OF SKIN WOUNDS What is the relationship between granulation tissue and scar tissue?

Answer 55

A greater volume of granulation tissue generally results in a greater mass of scar tissue.

Question 56

# HEALING OF SKIN WOUNDS What may be seen with substantial scar formation?

Answer 56

accompanied by thinning of the skin surface or epidermis.

Question 57

# HEALING OF SKIN WOUNDS helps to close the wound by decreasing the gap between its dermal edges and reducing the wound surface area

Answer 57

Wound contraction

Question 58

# HEALING OF SKIN WOUNDS the formation of a network of myofibroblasts, which are modified fibroblasts with contractile properties.

Answer 58

Wound contraction

Question 59

# WOUND STRENGTH What is the wound strength of carefully sutured wounds compared to normal skin?

Answer 59

Carefully sutured wounds have approximately **70% of the strength of normal skin**, largely because of the placement of sutures.

Question 60

# WOUND STRENGTH he recovery of tensile strength results from the excess of collagen synthesis over collagen degradation during the **first 2 months** of healing by?

Answer 60

cross-linking of collagen fibers and increased fiber size

Question 61

# WOUND STRENGTH What percentage of normal strength do wounds reach by 3 months?

Answer 61

Wound strength reaches approximately **70% to 80%** of normal by 3 months but usually does not substantially improve beyond that point.

Question 62

What are the Systemic factors affecting the wound Healing

Answer 62

1. Nutrition (Protein, Vitamin C) 2. Metabolic Status (Diabetes) 3. Circulatory Status (Arteriosclerosis) 4. Hormones (Glucocorticoids)

Question 63

What are the local factors affecting the wound healing

Answer 63

1. infection 2. Mechanical Factors 3. Foreign Bodies 4. Size, Location and Type of wound

Question 64

# COMPLICATIONS IN CUTANEOUS WOUND HEALING What are the types of complications in cutaneous wound healing?

Answer 64

a) Deficient scar formation b) Excessive formation of the repair components c) Formation of contractures

Question 65

# COMPLICATIONS IN CUTANEOUS WOUND HEALING What does deficiency in repair components lead to?

Answer 65

It leads to **inadequate formation of granulation tissue**, resulting in opening of the wound with dehiscence and ulceration.

Question 66

# EXCESSIVE SCARRING Grossly, the deposition in a hypertrophic scar is within the border of the wound.

Answer 66

Hypertrophic Scars

Question 67

# EXCESSIVE SCARRING Grossly, the deposition in a keloid may extend out of the border of the wound.

Answer 67

Keloid

Question 68

# EXCESSIVE SCARRING Microscopically, the deposition of collagen in a hypertrophic scar is parallel to the skin surface.

Answer 68

Hypertrophic Scars

Question 69

# EXCESSIVE SCARRING Microscopically, the deposition of collagen in a keloid is haphazard

Answer 69

Keloid

Question 70

the formation of excessive amounts of granulation tissue that protrudes above the level of the surrounding skin and blocks reepithelialization.

Answer 70

Exuberant granulation ## Footnote This process has been called, with more literary fervor, proud flesh.

Question 71

# EXUBERANT GRANULATION How must excessive granulation be treated?

Answer 71

removed by **cautery** or **surgical excision** to permit restoration of the continuity of the epithelium.

Question 72

# EXUBERANT GRANULATION are neoplasms that lie in the interface between benign and malignant (though low-grade) tumors.

Answer 72

Desmoids, or aggressive fibromatoses,

Question 73

# EXUBERANT GRANULATIONExuberant granulation What can exaggeration of contraction lead to?

Answer 73

An exaggeration of contraction gives rise to contracture, resulting in **deformities of the wound and the surrounding tissues**.

Question 74

When are contractures commonly seen?

Answer 74

after serious burns and can compromise the movement of joints.