Fibrous Healing and Repair

Question 1

What tissue process are initiated following an injury?

Answer 1

Regeneration

Repair

Question 2

What is meant by regeneration?

Answer 2

The process of replacing or restoring damaged or missing cells, tissues, organs, and even entire body parts

Question 3

What are labile cells?

Answer 3

Cells undergoing continuous proliferation, they have a short lifespan and rapid turnover

Question 4

What are stable cells?

Answer 4

Divide infrequently but can divide rapidly when stimulated by lost cells (such as after a fracture)

Question 5

What are permanent cells?

Answer 5

Cells which divide only in the foetus and cannot be replaced when lost

Question 6

Epithelial cells in the skin and digestive system are what type of cell?

Answer 6

Labile, they undergo continuous proliferation

Question 7

Bone and liver cells are what type of cell?

Answer 7

Stable, divide infrequently but can divide rapidly when stimulated by lost cells

Question 8

Neurons and cardiac muscle cells are what type of cell?

Answer 8

Permanent, they divide only in the foetus and cannot be replaced when lost

Question 9

What type of cell is an RBC?

Answer 9

Permanent, however, the bone marrow can create new ones. The existing ones cannot divide and therefore they are unable to regenerate

Question 10

In which tissue does primary intention healing occur?

Answer 10

Wounds with dermal edges close together

Question 11

In which tissue does secondary intention healing occur?

Answer 11

When sides of wound are not opposed and therefore healing must occur from the bottom up

Question 12

Which healing tends to be faster, primary or secondary?

Answer 12

Primary as the tissue loss is less extensive

Question 13

What is the end result of primary intention healing?

Answer 13

A complete return to function, with minimal scarring and a loss of skin appendages

Question 14

What is the end result of secondary intention healing?

Answer 14

The formation of fibrovascular connective tissue, (fibrous scar tissue)

Question 15

What are the 4 stages of wound healing? (in order)

Answer 15

Homeostasis
Inflammation
Proliferation
Remodelling

Question 16

In wound healing when does inflammation occur?

Answer 16

A couple of hours after to 6 days after the wound is created

Question 17

What is the first stage in the process of inflammation?

Answer 17

Once bleeding has stopped the blood vessels dilate to allow Leucocytes (WBCs) to enter the wound

Question 18

What are the growth factors of inflammation?

Answer 18

Proteins which activate the cells involved in the inflammatory process

Question 19

What role does macrophages have in inflammation?

Answer 19

Phagocytose damaged tissues / bacteria
Produce chemotaxins for WBC recruitment
Release proteases to digest dead tissues
Create cytokines to regulate tissue formation
Involved in release of matric metalloproteinases

Question 20

What occurs during the homeostasis phase of healing?

Answer 20

Platelet aggregation
Fibrin clot formation
Leukocyte migration

Question 21

When does the remodeling stage of fibrous healing occur?

Answer 21

Between 3 weeks and 2 years

Question 22

What are the stages of muscle healing and repair?

Answer 22

Destruction and inflammatory phase
Repair phase
Remodelling phase

Question 23

What occurs during the remodelling phase of healing?

Answer 23

Type I collagen accumulation
Crosslinking of collagen
Scar tissue formation
Increased tensile strength of skin

Question 24

When does the homeostasis stage of fibrous healing occur?

Answer 24

Between the time of wound and few hours after the wound

Question 25

When does the destruction and inflammatory stage of muscle healing occur?

Answer 25

1 - 3 days

Question 26

What occurs during the proliferation phase of healing?

Answer 26

Proliferation of fibroblasts
Provisional ECM synthesis
Granulation of tissue forms
Re-epithelialisation

Question 27

When does the remodelling stage of muscle healing occur?

Answer 27

3 - 6 weeks

Question 28

When does the repair stage of muscle healing occur?

Answer 28

3 - 4 weeks

Question 29

When does the proliferation stage of fibrous healing occur?

Answer 29

Between 4 and 21 days after the wound

Question 30

What occurs during the inflammatory stage of muscle healing?

Answer 30

Myofibres rupture and necrotise
Haematoma is formed
Inflammatory cells invade site through torn blood vessels
Replaced by monocytes
Macrophages remove necrotic fibres and produce chemotactic signals

Question 31

What occurs during the inflammatory stage of muscle healing?

Answer 31

Myofibres rupture and necrotize
Haematoma is formed
Inflammatory cells invade site through torn blood vessels
Replaced by monocytes
Macrophages remove necrotic fibres and produce chemotactic signals

Question 32

What is the role of macrophages during the inflammatory stage of muscle healing?

Answer 32

Remove necrotic myofibers (phagocytosis)
Produce chemotactic signals such as growth factors, cytokines and chemokines. (Some of these GFs can activate myogenic precursors called satellite cells)

Question 33

What is the function of scar tissue created by fibrin and fibronectin?

Answer 33

Gives the muscle strength to withstand contractions, and it gives the fibroblasts an anchoring site to invade the granulation tissue

Question 34

What occurs during the remodelling stage of muscle healing?

Answer 34

Newly formed myofibers mature
Scar tissue is reorganized and it contracts
In this process collagen fibres are realigned to position of maximum efficiency
Fibres are parallel to lines of tension
Gradually assumes normal appearance and function

Question 35

Scar tissue is formed by which molecules?

Answer 35

Fibrin and Fibronectin

Question 36

What occurs during the repair stage of muscle healing?

Answer 36

Regeneration of disrupted myofibres

Formation of connective tissue scar by fibrin and fibronectin