healig regeneration and repair

Question 1

Name three types of stem cells, the definition of each and examples of each

Answer 1

Unipotent- The stem cell can differentiate into one type of cell only (eg. Epithelia)
Multipotent- The stem cell can differentiate into more than one type of cell eg. haematopoetic stem cells
Totipotent- The stem cell can differentiate into all types of cells (eg. embryonic stem cells)

Question 2

where are stem cellls found in the intestine, epidermis, and liver?

Answer 2

intestine- at the bottom of the crypts
epidermis- in the basal layer adj to basement membrane
liver- between hepatocytes and bile ducts

Question 3

three types of tissue (classified into there regeneration abilities), definitions and examples

Answer 3

Labile- rapid proliferation, short lived cells eg. epithelia, haematopoetic cells
Stable- Normally slow proliferation, can be fast if need be eg. liver, bone, fibrous tissue and endothelium
Permanent- Cannot proliferate eg. neural tissue, skeletal muscle and cardiac muscle

Question 4

What are the requirements for regeneration to take place? 3

Answer 4

need an intact CT scaffold
Tissue damage can’t be extensive
damage must be in labile or stable tissue

Question 5

Describe the process of scar formation

Answer 5

sec to mins- haemostasis
min to hrs- acute inflammation
hrs-days- chronic inflammation
2-3 days- granulation tissue formation
7-10 days- early scar formation
weeks to years- scar maturation

Question 6

what does granulation tissue consist of?

Answer 6

Chronic Inflamm cells
fibroblasts and myofibroblasts
newly forming blood vessels

Question 7

Function of granulation tissue? 3

Answer 7

contracts and closes the hole
fills the gap
capilleries supply oxygen and nutrients and cells

Question 8

What types of cells are involved in fibrous tissue and what are their functions? 3

Answer 8

Inflammatory cells- Phagocytose debris and produce chemical mediators
Endothelial cells- proliferate stimulating angiogenesis
fibroblasts and myofibroblastss- synthesise collagen and wound contraction

Question 9

Describe the type of wound in primary intention

Answer 9

Incised, closed wound
no infection
minimal tissue loss

Minimal clot and granulation tissue in primary intention

Question 10

Describe what takes place in healing by primary intention? 3

Answer 10

Epidermis regenerates
Dermis undergoes fibrous repair
Minimal scar formed

Question 11

Describe the type of wound in healing by secondary intention

Answer 11

excisional wound, extensive tissue loss, separated edges, infected maybe

You get an open wound filled with granulation tissue

Question 12

Describe what takes place in healing by secondary intention

Answer 12

considerable wound contraction and substantial scar contraction

Question 13

Describe the process of bone breakage

Answer 13

1. Haematoma formation- fills the gap and surrounds the injury
2. Granulation tissue forms
3. Soft callus formation- fibrous tissue and cartilage form within which woven bone forms
4. hard callus formation- woven bone forms
5. Lamellar bone forms- remodelled in line with mechanical stress

Question 14

What properties of the wound affect wound healing? 7

Answer 14

location
type
size
shape
mechanical stress
blood supply
infection or foreign bodies

Question 15

What general properties affect wound healing?

Answer 15

age
diabetes
obesity
drugs (eg. steroids)
malnutrition
vitamin deficiencies
anaemia

Question 16

Name 6 complications of fibrous repair

Answer 16

disruption of the complex tissue relationships
Keloid scar
Excessive scar contraction
adhesions–>compromised organ function and blockage of tubes
insufficient fibrosis
loss of function

Question 17

Why does a donor site for skin grafts able to grow back quickly

Answer 17

skin taken at a very superficial level

so no disruption to the complex tissues

Question 18

Where is type one collagen found?

Answer 18

bones, tendons, ligaments, cornea, skin, sclera, blood vessels hollow organs

Question 19

where is type 4 collagen found? and what secretes it?

Answer 19

basement membrane

epithelial cells

Question 20

Describe the process of how collagen is made?

Answer 20

ppt alpha chains synthesised in the ER
enzymatic modification including vit C dependent hydroxylation
alpha chains align and form cross linkages
forms procollagen triple helix
this is secreted
procollagen then cleaved to form tropocollagen
tropocollagen polymerises to form microfibrils and then fibrils
fibrils–>fibres

Question 21

Describe what is meant by contact inhibition

Answer 21

Signalling molecules on cell surfaces inhibit proliferation
Such as cadherins and integrin
this is altered in cancer

Question 22

8 functions of growth factors?

Answer 22

inhibition of division
locomotion
contractility
differentiation
viability
angiogenesis
activation

Question 23

Name four types of growth factor

Answer 23

epidermal
platelet derived growth factor
vascular
TNF