Tissue Injury & Repair

Question 1

Can the number of heart cells increase (hyperplasia)?

Answer 1

No - the heart has a fixed number of cells

Question 2

What is healing the response of?

Answer 2

1) Wound
2) Inflammatory process
3) Cell necrosis

Question 3

What 2 processes are involved in healing?

Answer 3

1) Regeneration (restore normal tissue)

2) Repair (tissue can regain its normal function)

Question 4

Which organ is unable to regenerate?

Answer 4

Heart - it heals by fibrosis, leading to scar tissue

Question 5

Definition of regeneration:

Answer 5

The growth of cells and tissues to replace lost structures, with the aim to restore normal tissue

Question 6

What are the 2 requirements for regeneration to take place?

Answer 6

1) A tissue that has proliferative capacity

2) Extracellular matrix and proteins

Question 7

Which organ has a high proliferative capacity?

Answer 7

Liver

Question 8

Definition of repair:

Answer 8

A combination of regeneration and scar formation in order to restore the normal function of the tissue

Question 9

At what level of the skin does regeneration take place?

Answer 9

Epithelium

Question 10

At what level of the skin does scar formation take place?

Answer 10

Subcultaneous

Question 11

What depends on which type of healing takes place?

Answer 11

The degree of injury

Question 12

Which type of healing process will occur for each of the 2 types of inflammation?

Answer 12

Acute inflammation -
Superficial skin = regeneration
Subcultaneous = repair
Chronic inflammation - fibrosis

Question 13

Evaluation of the ability for regeneration to take place in Amphibians:

Answer 13

Good regenerative abilities

Question 14

Evaluation of the ability for regeneration to take place in mammals:

Answer 14

Only have a few true examples of regernation

Question 15

Name the examples of true regeneration in mammals:

Answer 15

1) Liver
2) Superficial skin layer
3) Bone fractures

Question 16

How do mammals compensate for only having a few examples of true regeneration?

Answer 16

Hyperplasia and hypertrophy

Question 17

When does fibrosis occur and how is the scar formed?

Answer 17

Fibrosis occurs when the degree of injury is serious and chronic inflammation ha occurred.
Scar formation occurs when collagen and extra-cellular matrix components are deposited

Question 18

Which cells are responsible for depositing the collagen and extra-cellular matrix components ?

Answer 18

Parenchymal cells and fibroblasts

Question 19

The sequence of healing from day 0-14:

Answer 19

0-3: 1) Injury 2) Inflammation 3) Angiogenesis 4) Migration of parenchymal cells and fibroblasts
0-7: 1) Pro-liferation of parenchymal cells and fibroblasts
9-14: Depends on level of injury/ type of inflammation
If acute:
Superficial - regeneration
Subcultanous - repair
If chronic:
Fibrosis - scar formation

Question 20

What are the 2 types of wounds?

Answer 20

First Intention and Secondary Intention

Question 21

What are first intention wounds?

Answer 21

The edges of the wound will be close together and so healing of the wound doesn’t take long

Question 22

What are secondary intention wounds?

Answer 22

The edges of the wound will be far apart and so it takes longer for the wound to heal

Question 23

What is the difference between the healing results of first intention and secondary intention wounds?

Answer 23

First intention: small scab

Secondary intention: large scab with larger amounts of granulation tissue

Question 24

What occurs in secondary intention to try and bridge the gap between the edges of the wound?

Answer 24

Wound contraction

Question 25

What are the 2 classes of factors that affect wound healing?

Answer 25

Local factors and systemic factors

Question 26

Name the 4 local factors that affect wound healing?

Answer 26

1) Size of the wound 2) How well vascularised the tissue is 3) Type of wound - clean or infected 4) Mechanical forces (e.g. scab picking)

Question 27

Name the 4 systemic factors that affect wound healing?

Answer 27

1) Nutritional status 2) Metabolic status 3) Circulatory status 4) Hormones

Question 28

Which hormones can prolong healing?

Answer 28

Steriods

Question 29

What are the 3 complications of wound healing?

Answer 29

1) Deficient scar formation - resulting from open wounds 2) Keloid scar formation - resulting from excessive healing 3) Contractures - resulting from burn wounds

Question 30

How can wound infections be prevented?

Answer 30

1) Keeping the area clean 2) Regular wound dressings 3) Looking out for signs of injections

Question 31

Is bleeding at the site of infection normal?

Answer 31

Each area of injury will have a normal degree of bleeding. Anything beyond this normal degree will indicate internal bleeding.

Question 32

Define pressure/bed sores and where are they normally located?

Answer 32

Unrelieved pressure over an area of the body and they are normally located on boney areas

Question 33

What causes pressure/bed sores?

Answer 33

1) Lack of blood supply to the area due to the unrelieved pressure 2) Shearing factors that traumatise skin

Question 34

What results from pressure/bed sores?

Answer 34

1) Ischaemia 2) Cell necrosis 3) Cellulitis 4) Superimposed and deep seated infections 5) Osteomyelitis