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BIOSCI107 > Skin/Wound Healing > Flashcards

Skin/Wound Healing Flashcards

1
Q

What is the function of human skin?

A

To be a protection barrier against the environment

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2
Q

How much blood does the skin hold? (percentage of total blood volume)

A

8-10% of total blood volume

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3
Q

Vessel constriction in the dermis reduces what?

A

Blood flow

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4
Q

Vasodilatation in the dermis increases what?

A

Blood flow

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5
Q

What is vitamin D synthesis?

A

The vitamin D precursor requires modification by UV before the active form can be made in the liver

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6
Q

What is the epidermis and what is its functions?

A

The top layer of skin provides a barrier, continues the renewal of skin

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7
Q

What does the epidermis consist of?

A

Layers of keratinocytes

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8
Q

What are keratinocytes?

A

Cells that produce keratin, they visibly divide and move around and are important for the protective barrier function

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9
Q

Thin skin has how many layers?

A

3

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10
Q

Where on the body is thick skin found?

A

Fingertips, palms and soles of the feet

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11
Q

How many layers does thick skin have and what is the 5th layer called?

A

5, the fifth layer is the stratum lucidum

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12
Q

What is the bottom layer of the epidermis?

A

Stratum basale

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13
Q

What is the function of the stratum basale? (2 things)

A
  • Keratinocyte stem cells are the reservoirs for a lifetime of renewal
  • Transit amplifying keratinocytes to proliferate (divide) to provide cells for the upper cells of the epidermis
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14
Q

What is the 4th layer of the epidermis called?

A

The stratum spinosum

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15
Q

What occurs in the stratum spinosum?

A

Keratinocytes start to flatten out

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16
Q

What holds cells together in the stratum spinosum?

A

Keratin intermediate filaments and desmosome junctions

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17
Q

What is the 3rd layer of the epidermis?

A

The stratum granulosome

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18
Q

What are stratum granulosomes?

A

Flattened keratinocytes undergoing apoptosis

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19
Q

What is apoptosis?

A

Programmed cell death

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20
Q

What do Lamellar granules do in the stratum granulosome?

A

They fuse to the plasma membrane and release lipid-rich secretions to help form the barrier

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21
Q

What are keratohyalin and what layer are they found in?

A

They are dark granules that help form keratin intermediate filaments into keratin, found in the stratum granulosome

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22
Q

What is the 2nd layer of the epidermis?

A

The stratum lucidum

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23
Q

Where is stratum lucidum present?

A

In thick skin (palms, fingertips, soles of feet)

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24
Q

What is the top layer of the epidermis?

A

The stratum corneum

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25
What does the stratum corneum consist of?
25-30 layers of flattened dead keratinocytes that overlap like scales of a snake
26
What is the function of the stratum corneum?
Works to provide that barrier and keeps moisture in and the outside world out
27
What is the process of stratification?
Proliferating keratinocytes on the bottom of the epidermis push cells up/away from the dermis
28
How often does a complete epidermal turnover occur?
Approximately once a month
29
What is the basement membrane?
The interface between the dermis and epidermis
30
What could a mutation in the basement membrane lead to? (disease)
Epidermylosis bullosa
31
What happens if keratinocytes don't attach to the BM?
The epidermis can easily detach due to shear forces
32
What are rete ridges and what do they provide?
Rete ridges are dermal papillae that have a contour to provide resistance against shear forces. it strengthens the attachment of the epidermis and dermis
33
What cells cause pigmentation and where do they reside?
Melanocytes - they reside at the BM on the epidermal side
34
What do melanocytes make and what do these contain?
Melanosomes (vesicles), they contain the pigment melanin
35
How many keratinocytes on average make contact with a melanasome?
On average, 36
36
What is melanin and how many/what types are there?
The pigment that gives skin its colour, there are 2 types: Pheomelanin and eumelanin
37
What tones does pheomelanin provide?
The yellow-red tones
38
What tones does eumelanin provide?
The brown/black tones
39
Melanin protects the skin from what?
UV damage (it absorbs it protecting the nucleus)
40
What protects the keratinocytes DNA from UV damage?
The nuclear cap
41
What is the function of Langerhans cells?
They surveil the epidermis for foreign organisms
42
What is the dermis made up of and what is its key function?
It is a dense matrix made up of collagen and elastin fibres, the dermis provides strength
43
Does the dermis turnover often?
No, it is stable therefore turnover is minimal
44
What do fibroblasts produce?
Produce collagen and elastin fibres which provide strength and elasticity
45
The dermis is a .... system?
Vasculature system - supplies nutrients and waste for both itself and the epidermis
46
What is the transverse section of skin made up of?
Papillary dermis and the reticular dermis
47
What is the papillary dermis made up of? Does it have a low or high cell density?
Loose connective tissue and has a high cell density
48
What is the reticular dermis made up of? Does it have a low or high cell density?
Dense connective tissue and has a low cell density
49
How many types of wound healing are there and what are they called?
3 wound types: - Superficial - Partial-thickness - Full-thickness
50
Superficial wounds cause damage to what layer of the skin only?
Only damages the epidermis
51
How does healing occur in superficial wounds?
By the migration of keratinocytes from wound edges and dermal appendages (sweat glands, hair follicles etc)
52
What can occur once the keratinocytes are in contact on all sides in superficial wound healing?
Stratification can occur to reform the epidermis
53
What layers of the skin do partial-thickness wounds damage?
All of the epidermis, part of the dermis
54
What are the four phases of healing (in order)?
- Inflammatory phase: Immune cells come in and clean up the wound - Migratory phase: Keratinocytes migrate from the wound edge and appendages, fibroblasts migrate into the clot and make collagen fibres, keratinocytes migrate into the wound edge - Proliferative phase: Keratinocytes proliferate (increase) - Maturation phase: Epidermal stratification occurs and the scab falls off
55
What layers of the skin do full-thickness wounds effect?
All of epidermis and dermis is destroyed, hypodermis can be destroyed too which can expose bone/muscle
56
Why are full-thickness wounds hard to heal?
Because all reservoirs of the epidermal stem cells have been destroyed
57
How do full-thickness wounds usually turn out/heal as?
Scar tissue
58
What wound treatment is usually required for patients with full-thickness wounds?
Split thickness skin grafts
59
What happens during a split-thickness skin graft procedure?
It removes all of the epidermis and part of the dermis from a healthy donor site that is undamaged and the graft then covers the wound and will heal in 10-14 days (the donor site becomes a partial thickness wound)
60
What kind of tissue would negatively affect a graft take?
Any residual necrotic tissue
61
What would happen if a patient had burns to 30% of their body and therefore could not take healthy skin grafts from themselves? And what happens eventually?
They would receive cadaver skin, but this eventually gets rejected so must be repeated several times until fully healed
62
How do scientists make engineered skin?
Take a small sample of skin and isolate to grow keratinocytes and fibroblasts. This will eventually grow large sheets of autologous full-thickness skin and this becomes a permanent coverage solution
63
What are the limitations of skin engineering?
The skin doesn't have pigmentation, hair follicles, sebaceous glands. Still a long way to go as there is a lack of functionality which will impact the patient long term

BIOSCI107 (5 decks)

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