Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Path Pro 2023 > Regeneration And Repair (Session 4) > Flashcards

Regeneration And Repair (Session 4) Flashcards

1
Q

What 3 processes are involved in wound healing?

A
  • Haemostasis (formation of a blood clot)
  • Inflammation
  • Regeneration and/or repair
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is regeneration?

A

Regrowth of cells (with minimal evidence of injury)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What injuries is regeneration only possible?

A
  • Minor injuries (superficial skin incision/abrasion)
  • If the injury is more extensive than that, tissue has to heal by REPAIR
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Is regeneration only done in response to injury?
Explain

A
  • No
  • It can also be physiological, e.g. production of new blood cells in bone marrow and new skin cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Where do new cells come from?

A

Stem cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are stem cells? (4)

A
  • undifferentiated cells
  • can differentiate into other fully mature cell types
  • can self-renew
  • replace dead/damaged cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the 3 main types of stem cell?
What do they do?
Give examples of each

A
  • Totipotent
  • produce all cell types
  • eg. embryonic stem cells
    (T for total)
  • Multipotent
  • produce several cell types, but not all
  • eg. haematopoietic stem cells
  • Unipotent
  • produce 1 cell type
  • eg. epithelial stem cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Give 3 examples of where in the tissues stem cells are found

A
  • Stem cells in the epidermis - found in basal layer (unipotent)
  • Stem cells in intestinal mucosa - bottom of crypts
  • Stem cells in the liver - between hepatocytes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Tissue regeration types

A

Labile
Stable
Permanent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Labile tissue:
What it does in terms of regeneration + examples

A
  • continuous replication of cells
  • eg. epithelium, haematopoietic tissue
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Stable tissue
What it does in terms of regeneration + examples

A
  • normally low level of replication but can undergo rapid replication if required, if that tissue becomes injured or damaged
  • eg. liver, kidneys, pancreas, bone, endothelium, smooth muscle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Permanent tissue
What it does in terms of regeneration + examples

A

Cells do not replicate - left cell cycle and cannot re enter - if damage occurs, they can only heal by repair

Neurones, skeletal muscle, cardiac muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Which stage of the cell cycle is each tissue type involved in?

A

labile - continuous cycling (G1,S,G2,M, back to G1)always in cell cycle
stable - left cell cycle, can re-enter if stimulated (G0)
permanent - left cycle, cannot re-enter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is required for tissues to regennerate?

A

An Intact connective tissue/collagen architecture (to build upon)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What happens if there is significant damage to the connective tissue architecture of cells that usually regenerate?

A
  • Regeneration cannot occur
  • Instead, healing has to take place in a process called repair
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is fibrous repair?

A

Replacement of functioning tissue with a scar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

In what cases does fibrous repair occur? (scar formation)

A

Necrosis of permanent tissues : Fibrous repair is the only option

Necrosis of labile or stable tissues:
- Collagen framework has been destroyed
- On going chronic inflammation
Then fibrous repair will occur

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What does necrosis of permanent tissue lead to after an injury?

A

Fibrous repair (i.e. a scar)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What does necrosis of labile or stable tissue lead to after an injury?

A
  • collagen framework intact = regeneration
  • collagen framework destroyed = fibrous repair (ie. a scar)
  • on-going chronic inflammation = fibrous repair (ie. a scar)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

4 stages of fibrous repair (scar formation)

A

1) Bleeding and haemostasis
2) Inflammation
3) Proliferation
4) Remodelling

BIPR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Bleeding and haemostasis stage of scar formation (3)

A
  • Formation of blood clot
  • Prevention of blood loss
  • Takes Seconds to minutes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Inflammation stage stage of scar formation (3)

A
  • Acute then chronic
  • Digestion of blood clot and necrotic tissue by macrophages and neutrophils
  • Takes minutes to days
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Proliferation stage stage of scar formation (4)

A
  • proliferation of capillaries (angiogenesis)
  • proliferation of fibroblasts and myofibroblasts which lay down extracellular matrix (containing collagen and elastin for tissue architecture)
  • The proliferation of all of these results in tho production of granulation tissue
  • takes days to weeks
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are the functions of granulation tissue? (3)

A
  • Fills gap - to try and prevent pathogen entry
  • Capillaries can supply oxygen and nutrients to the injured area (angiogenesis)
  • Contracts and closes wound
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is this an image of?
Label 3 structures that are present

A

Granullation tissue under microscope with H and E Staining

1) Blood vessels:
- The empty spaces with RBC’s in them
- Lined by endothelial cells
- Abnormal shape (no tubular structure), instead branch in unusual ways (elliptical shape) as they are newly developing, formed because of angiogenesis

2) Chronic inflammatory cells (macrophages, lymphocytes, neutrophils, eosinophils, left over from inflammatory phase of scar formation)

3) Extracellular matrix - pink material (collagen and elastin being laid down as part of scar formation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

T/F The vascularity of granulation tissue increases over time

A

F - The vascularity of granulation tissue decreases over time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

How can granulation tissue appear?

A

Pale yellow and shiny

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Remodelling phase (6)

A

Maturation of scar:

  • Reduced cell population (ie apoptosis of inflammatory cells)
  • Increased collagen deposition
  • Myofibroblasts contract, bringing edges of wound closer together
  • Fibrous scar forms
  • Takes weeks to years
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Which cells involved in fibrous repair, and what do they do? (6)

A

Neutrophils & macrophages:
- Phagocytosis
- Release inflammatory mediators that control and coordinate the inflammatory response

Lymphocytes:
- eliminate pathogens
- Co ordinate other cells involved in inflammatory processes

Endothelial cell:
- proliferation
- Angiogenesis

Fibroblast - secrete collagen and elastin which forms ECM

Myofibroblast :
- Express intracellular actin
- Wound contraction to make scar smaller and smaller

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Name the following cells

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

How do fibroblasts and myofibroblasts appear on H&E? (4)

A

Spindle shaped (elongated) nucleus

Star shape cytoplasmic extentions (cant usually see)

  • They are similar in appearance
  • A myofibroblast is between a fibroblast and a smooth muscle cell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Where is collagen type 1 found? (7)

A
  • Bone
  • Skin
  • Tendon
  • Ligaments
  • Sclera
  • Cornea
  • Vessels etc.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Where is type 4 collagen found? (3)

A
  • Basement membrane
  • Lens
  • Glomerular filtration etc.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What are thee different names of collagen at different stage

A

Pre-pro collagen
Procollagen
Tropocollagen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Step 1 collagen synthesis (3)

A
  • Occurs In Endoplasmic Reticulum of (myo)fibroblasts
  • Polypeptide alpha chain (pre pro collagen)
  • Gets hydroxylated (Vit C dependent)
36
Q

Step 2 collagen synthesis (3)

A
  • In cytoplasm of (myo)fibroblasts
  • Hydroxylated alpha chains are cross linked to form a triple helix
  • That triple helix is called procollagen
37
Q

Stage 3 of collagen synthesis (4)

A

Occurs in extracellular space:

  • Pro collagen gets transported out of cell
  • C and N terminals of procollagen cleaved off
  • That triple helix left behind is called tropocollagen
38
Q

Stage 4 collagen synthesis (3)

A
  • Multiple molecules of tropocollagen are cross linked to form a microfibril
  • Multiple Microfibrils are cross linked to form a fibril
  • Multiple fibrils are BOUND TOGETHER to form collagen fibres
39
Q

Describe the 4 stages of collagen synthesis

A

Stage 1:
- Occurs In Endoplasmic Reticulum of myofibroblasts and fibroblasts
- Polypeptide alpha chain (pre pro collagen)
- Gets hydroxylated (Vit C dependent)

Stage 2:
- In cytoplasm of (myo)fibroblasts
- Hydroxylated alpha chains are cross linked to form a triple helix
- That triple helix is called procollagen

Stage 3:
- Pro collagen gets transported out of cell
- C and N terminals of procollagen cleaved off
- That triple helix left behind is called tropocollagen

Stage 4:
- Multiple molecules of tropocollagen are cross linked to form a microfibril
- Multiple Microfibrils are cross linked to form a fibril
- Multiple fibrils are BOUND TOGETHER to form collagen fibres

40
Q

What class of drugs inhibits collagen synthesis? Why?

A

corticosteroids are immunosuppressive so inhibit wound healing

41
Q

Diseases of defective collagen

A

Aquired:
Scurvy

Inherited:
Ehlers-Danlos
Osteogenesis Imperfecta
Alport syndrome

42
Q

What is scurvy and why does it result in defective collagen?

A
  • Vitamin C deficiency =
  • Inadequate hydroxylation of pre-procollagen
  • Defective triple helix structure and defective collagen
43
Q

Scurvy symptoms/signs (5)

A
  • Poor wound healing
  • Tendancy to bleed often from minor injuries
  • Bruising
  • Bleeding of gums
  • Tooth loss
44
Q

What is Ehlers Danlos syndrome?
What are 4 symptoms?

A
  • inherited disease of defective collagen
  • collagen fibres lack adequate tensile strength
  • Poor wound healing
  • Hypermobile joints
  • Easy bone breaking and Joint dislocation
  • rupture of the colon and, in some forms, large arteries.
45
Q

What would the Skin of people with Ehlers Danlos be like? (3)

A

Hyperextensible
Fragile
Suceptible to injury

46
Q

What is Osteogenesis imperfecta?
Give 4 symptoms

A
  • Inherited disease of defective collagen
  • Brittle bone disease
  • BLUE SCLERA - too little collagen so is not transparent
  • Easy breaking and dislocation of bones
  • Hearing impairment
  • Dental abnormalities
47
Q

What is Alport syndrome?
Give 4 symptoms

A
  • Inherited disease of defective collagen
  • X linked - MALE MORE AFFECTED
  • Type 4 collagen affected

Symptoms:

Dysfunction of:
- Glomerulus basement membrane
- Cochlea of ear
- Lense of eye
(deafness, eye disorders)

  • Blood in urine, which progresses to chronic renal failure
48
Q

In terms of regeneration and repair, why do cells communicate with each other?

A
  • To stimulate/inhibit proliferation
49
Q

How is regeneration controlled? (3)

A
  • Direct cell to cell contact
  • Local mediators (e.g. growth factors)
  • Hormones
50
Q

How does direct cell to cell contact inhibit repair? (3)

A

Contact inhibition:

  • Isolated cells replicate until they encounter other cells
  • Cadherins (cell surface receptors) bind between cells and inhibit further proliferation
51
Q

In the vein of cell to cell contact, how can cancer arise (4)

A
  • Mutations in cadherins is one of the many causes of cancer
  • Cadherins are defective
  • They will be unable to tell cells to stop dividing
  • Uncontrolled cellular proliferation is one of the hallmarks of cancer

Continued proliferation = multilayers

52
Q

What are Growth factors?

A

Polypeptides that act on cell surfaces

53
Q

What do growth factors do? (2)

A
  • Causes cell to enter cell cycle and proliferate
  • Helpful for healing (angiogenesis etc)
54
Q

Growth factor examples (4)

A
  • Epidermal GF
  • Vascular Endothelial GF
  • Platelet derived GF
  • Tumour necrosis factor
55
Q

Two types of skin healing

A
  • Healing by Primary intention
  • Healing by Secondary intention
56
Q

Describe healing by primary intention (6)

A
  • Takes place in incision wounds (wounds where the edges of the wound are apposed, next to each other)
  • When we sulture a wound, we are bringing edges of the wound together so it can heal by Primary intention
  • Minimal clot and granulation tissue = small scar
  • Epidermis regenerates (labile tissue type/cell population)
  • Dermis undergoes fibrous repair (as it is a permanent tissue type)
  • Small scar left, which gets smaller over time

(e.g. my eyebrow scar)

57
Q

What is healing by secondary intention? (8)

A
  • Significant tissue loss
  • Unapposed edges (separated) , so it’s not possible to brig the edges of wound together
  • Or there may be something in the middle of the wound, preventing the edges from coming together (ie infection/ulcer/abcess)
  • Abundant clot, inflammation and granulation tissue
  • Considerable wound contraction required from myofibroblasts in order to try make wound smaller
  • Dermis requires significant repair
  • Epidermis regenerates from edges
  • Takes long time to heal, danger of reinfection and repeated trauma to this wound
58
Q

Name and describe the stages of fracture healing?

A

1) Haematoma formation
- Haematoma surrounds injury
- Granulation tissue forms

2) Soft callus formation
- After 1 week
- It is a combo of fibrous tissue and cartilage
- Woven bone begins to form (quite weak)

3) Hard callus formation
- After several weeks
- Woven bone gradually reorganised (by osteoclasts) to lamellar bone (stronger than woven bone)

4) Bone Remodelling
- Takes months to years
- Lamellar bone remodelled to original outline of bone

59
Q

How long for soft and hard callous formation?

A
  • 1 week soft
  • Several weeks hard
60
Q

How long for a fracture to be completely remodelled?

A

Months/years

61
Q

Give 2 types of factors influencing wound healing

A
  • Local
  • Systemic
62
Q

Local factors influencing wound healing (5)

A
  • Size of wound
  • Location of wound
  • Blood supply to that area of the body
  • Infection
  • Foreign bodies
63
Q

Systemic factors influencing wound healing (7)

A
  • Age (older = less efficient wound healing)
  • Anaemia/hypoxia/hypovolaemia (= reduced blood supply so less effective wound healing)
  • Obesity
  • Diabetes (nerve and blood vessel damage)
  • Drugs
  • Vitamin deficiency (e.g. Vit C)
  • Malnutrition
64
Q

Why would a scar stretch over the years?

A

elastic fibres don’t regenerate in an area of damaged skin and
therefore scars can stretch as they mature

65
Q

Complications of fibrous repair (6)

A
  • Insufficient fibrosis
  • Excessive fibrosis
  • Adhesions
  • Loss of function/architecture
  • ## Excessive scar contraction
66
Q

What does insufficient fibrosis result in?

A
  • Wound dehiscence (opening up of a wound)
67
Q

When does insufficient fibrosis often occur? (4)

A
  • Obese patients
  • Elderly
  • Malnutrition
  • Steroid use
68
Q

What is known about control mechanisms in regeneration and fibrous repair?

A

Cells communicate with each other to produce a fibroproliferative response.

69
Q

Cell to cell communication can occur via what?

A
  • Via local mediators (such as growth factors)
  • By hormones
  • By direct cell-cell or cell-stroma contact.
70
Q

Considering local mediators and hormones, cell communication can be: (3)

A
  • Autocrine
  • Paracrine
  • Endocrine
71
Q

Describe autocrine signalling

A

cells respond to the signalling molecules that they themselves produce.

72
Q

Describe paracrine signalling

A

a cell produces the signalling molecule, this acts on adjacent cells. The
responding cells are close to the secreting cell and are often of a different type.

73
Q

Describe endocrine signalling

A

hormones are synthesised by cells in an endocrine organ, they are then conveyed in the blood stream to target cells to effect physiological activity.

74
Q

Out of all local mediators, what are some of the most important when it comes to regeneration and fibrous repair?

A

growth factors

75
Q

1) What are growth factors?

2) What codes for growth factors?

3) What are growth factors considered as?

4) Why?

A

1) Polypeptides that act on specific cell surface receptors.

2) Proto-oncogenes

3) ‘local hormones’

4) as they act only over a short distance or even on the secreting cell itself.

76
Q

1) Describe the variation of what growth factors act on

2) Describe the effects of growth factors

3) Describe how they work

A

1) some act on many cell types, some have restricted targets.

2) They stimulate cell proliferation or inhibition but may also affect cell locomotion, contractility, differentiation, viability, activation and angiogenesis.

3) They bind to specific receptors and stimulate transcription of genes that regulate the entry of the cell into the cell cycle and the cell’s passage through it.

77
Q

Name 4 types of growth factor

A
  • Epidermal growth factor
  • Vascular endothelial growth factor
  • Platelet-derived growth factor
  • Tumour necrosis factor
78
Q

1) What effects does epidermal growth factor have?

2) Name things that produce epidermal growth factor

3) What does epidermal growth factor bind to?

A

1) Mitogenic for epithelial cells, hepatocytes and fibroblasts

2) keratinocytes, macrophages and inflammatory cells;

3) binds to epidermal growth factor receptor (EGFR)

79
Q

What does vascular endothelial growth factor do?

A

potent inducer of blood vessel development (vasculogenesis) and role in growth of new blood vessels (angiogenesis) in tumours, chronic inflammation and wound healing

80
Q

1) Where is platelet derived growth factor stored?

2) When is it released?

3) Name some other things that produce it

A

1) stored in platelet alpha granules

2) released on platelet activation

3) also produced by macrophages, endothelial cells, smooth muscle cells and tumour cells; causes migration and proliferation of fibroblasts, smooth muscle cells and monocytes

81
Q

What does tumour necrosis factor do?

A

induces fibroblast migration, fibroblast proliferation and collagenase secretion.

82
Q

1) What happens when normal cells become isolated from other cells around them?

2) What is this called?

3) What process does this occur in?

4) What does this process get altered in

A

1)

83
Q

How do cells adhere to each other and extracellular matrix?

A
84
Q

What are cadherins?

What are they important in?

A
85
Q

What are integrins?

What are they important in?

A

Path Pro 2023 (21 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions