Regeneration and repair

Question 1

Three processes of wound healing

Answer 1

Haemostasis- vessels are open
Inflammation- tissue injury
Regeneration- structures have already been destroyed

Question 2

Regeneration

Answer 2

The growth of cells and tissues to replace lost structures . Can be normal or can occur after tissue damage

Question 3

How are cells induced to regenerate?

Answer 3

Growth factors in environment
Cell to cell communication
Electrical currents and nervous currents

Question 4

Three types of tissues

Answer 4

Labile
Stable
Permanent

Question 5

What are labile tissues?

Answer 5

The proliferate throughout life- replacing cells

Question 6

Examples of labile tissues

Answer 6

Epithelia, bone marrow, haemopoetic tissues

Question 7

What are stable tissues?

Answer 7

Normally have a low level of replication but can undergo low level of replication in response to the stimuli

Question 8

Examples of stable tissues

Answer 8

Parenchyma tissues, osteoclasts smooth muscle cells

Question 9

What are permanent cells?

Answer 9

Tissue that contain cells that have left the cell cycle and cannot undergo mitotic division

Question 10

Examples of permanent cells

Answer 10

Neurones, skeletal and cardiac muscles

Question 11

Stem cells

Answer 11

Many terminally differentiated cells cannot divide so stem cells replace these cell.
Stem cells are cells with prolonged proliferation activity

Question 12

Bone regenrative capacity

Answer 12

Very good

Question 13

Tendon and articular cartilage regenerative capacity

Answer 13

Poor, heal very slowly due to lack of blood supply

Question 14

Adipocyte regenrative capacity

Answer 14

None- just produces different adipocytes

Question 15

Epithelia regenerative capacity

Answer 15

Good except the lens of the eye

Question 16

Liver regenrative capacity

Answer 16

Excellent

Transplanted livers adjust to the size of the recipent

Question 17

Melanocytes regenrative capaccity

Answer 17

Tend to regenerate too much to too little

Question 18

Smooth muscle regenerative capacity

Answer 18

Very good

Question 19

Strained muscle regenerative capacity

Answer 19

Limited- regeneration from satelittle cells

Question 20

Peripheral nerves regenrative capacity

Answer 20

Regenerate at 1-3mm/day

Question 21

CNS regenrative capacity

Answer 21

None in humans

Question 22

Fibrous repair processes

Answer 22

Phagocytosis of necrotic tissue debris
Proliferation of endothelial cells- capillary growth
Proliferation of fibroblasta and myofibroblasts that synthesised collagen and cause wound contraction
Granulation tissue becomes less vascular
Scar matures and shrinks

Question 23

Scurvy

Answer 23

Due to vitamin C deficiencywhich is needed for hydroxylation of procollagen

Question 24

Ehlers Danilo’s syndrome

Answer 24

Skin is hyperextensible, fragile
Joints are suspectible to injury
Poor wound healing

Question 25

Osteogeneisis imperfecta

Answer 25

Brittle bone disease. Too little bone tissue | Also have blue sclera

Question 26

Alport syndrome

Answer 26

X linked disease abnormal type IV collagen- neural deafness and eye disorders

Question 27

Epidermal growth factor

Answer 27

Mitogenic for epithelial cells, hepatocytes, binds to epidermal growth factor receptor

Question 28

Vascular endothelial growth factor

Answer 28

Potent inducer of blood vessel development and new blood vessels in tumours and chronic inflammation

Question 29

Platelet derived growth factor

Answer 29

Stored in platelet alpha granules released on platelet activation

Question 30

Tumor necrosis factor

Answer 30

Induces fibroblast migration and proliferation and collagenase secretion

Question 31

Healing by primary intention

Answer 31

Occurs in closed non infected sutured wounds, where there is epithelial basement continuity but death of limited epithelial and CT

Question 32

Process of healing by primary intention

Answer 32

``` Haemostasis Inflammation Migration of cells Regenration Early scarring Scar maturation ```

Question 33

Primary intention healing- seconds to minutes

Answer 33

Arteries contract blood clots clot dehydrates and forms a scab preventing bacteria entering

Question 34

Primary intention healing mins to hours

Answer 34

Inflammation- neutrophils ward off bacteria

Question 35

Primary intention healing upto 48 hours later

Answer 35

Macrophages appear and begin to scavenge dead neutrophils become activated and secrete cytokines

Question 36

Process of healing by secondary intention

Answer 36

Granulation tissue grows inwards from the edges of the wound, large clot and necrotic debris. Myelofibroblasts cause the wound to contract

Question 37

Local factors which affect wound repair

Answer 37

``` Size, location and type of wound Blood supply Denervation Local infection Foreign bodies Necrotic tissue Mechanical stress Protection Surgical techniques ```

Question 38

Systemic factors which affect wound healing

Answer 38

``` Age Anaemia Hypoxia Hypovalemia Obesity Diabetes Malignancy Genetic disorders Drugs Vitamin deficiency Malnutrition ```

Question 39

Complications of fibrous repair

Answer 39

Fibrous adhesions that compromise organ function Loss of function Keloid scar Excessive scar causing disruption of tubes disfiguring scars