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Week 1 - Cells & Organelles > Function Of Skin > Flashcards

Function Of Skin Flashcards

1
Q

What are the 3 main functions of skin

A

Protection, regulation and sensation

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2
Q

What are the two types of skin protection

A

Immunological and physical

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3
Q

List the types of skin protection

A
  • mechanical impacts
  • pressure
  • variation in temperature
  • micro- organisms
  • radiation and chemicals
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4
Q

List the types of physiological function

A
  • Body temperature through sweat and hair
  • changes in peripheral circulation
  • fluid balance through sweat
  • synthesis of vitamin D
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5
Q

List types of sensational function

A
  • network of nerve cells which detect and relay changes to the environment, heat cold, touch and pain
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6
Q

List 3 layers which compose the skin

A
  • Epidermis
  • Dermis
  • fat subcutis ( hypodermis)
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7
Q

What other structures is the skin composed of

A

Glands within the layers, hair and erector pili muscle which is attached to the hair follicles

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8
Q

Name the 4 layers that compose the epidermis

A

Stratum basale
Stratum spinosum
Stratum Granulosum
Stratum corneum

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9
Q

How does the skin provide immunological and physical protection

A

Mechanical impacts
Pressure
Variation in temperature
Microorganism
Protection from radiation and chemicals

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10
Q

What types of physiological regulation does the body control

A

Body temperature
Change in peripheral circulation
Fluid balance through sweat
Synthesis of vitamin D

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11
Q

How does the skin feel sensation

A

Network through nerve cells which detect external signals are respond through relaying these messages - touch, pain, hot or cold sensations

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12
Q

Describe some other protective functions of the skin

A

Pigmentation protects against uv damage - melanocytes found in basal layer which produce melanin which is brown pigment that forms a protective cap over DNA nuclei

Protection against excessive water re absorption - this is achieved through sweating

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13
Q

List the 3 layers of the skin

A

Epidermis
Dermis
Hypodermics / subcutaneous

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14
Q

What type of epithelium is the epidermis composed of

A

Stratified squamous epithelium

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15
Q

What is the dermis composed of

A

Supportive connective tissue

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16
Q

What is the hypodermis/ subcutaneous layer formed of

A

Fat and loose connective tissue

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17
Q

How often is the epidermis replenished

A

Every 28 days
- 2 weeks to go from basal layer to granular layer
- 2 weeks to cross the stratum corneum

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18
Q

How many layers compose the epidermis

A

4 layers

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19
Q

What is the deepest layer in the epidermis

A

Stratum basal - cuboidal low columnar cells, mitotically active and aids in constant regeneration of other cells in the layer

Connected to the basement membrane through hemidesmosomes

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20
Q

Name the layer which is above stratum basal a

A

Stratum spinosum

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21
Q

What is stratum spinosum composed of

A

Polyhedral keratinocytes and Rich in desmosomes

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22
Q

Name the layer above stratum spinosum

A

Stratum granulosum

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23
Q

What’s the composition of stratum granulosum

A

In stratum granulosum is composed of cells which are flattening and contain kertohyalin granules which start to loose their nucleus and cytoplasm

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24
Q

Name the layer in epidermis above stratum granulosum

A

Stratum corneum

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25
What is the composition of stratum granulosum layer in epidermis
The cells become flattened as they loose their nucleus and cytoplasm Contain keratipohyalin granules
26
Name the layer of the epidermis which is above stratum granulosum
Stratum corneum
27
Describe the composition of stratum corneum layer
Large flat plate like envelopes filled with cross link keratin and lipids
28
Name the layer which connects the dermis with the epidermis
Basement membrane
29
List the layers of the epidermis in order
Basement membrane Stratum basale Stratum spinosum Stratum granulosum Stratum corneum
30
Which layer of the epidermis is found on thicker parts of the skin such as the foot or the palms of the hand
Stratum lucidum
31
Describe the composition of stratum lucidum
Layer of dead skin cells which provides protection to areas such as the sole of the foot or palms of the hand
32
Name the 5 cells found in the epidermis
Keratinocytes Merkel cells Langerhan cells Melanocytes
33
Where are keratinocytes located in the dermis
Keratinised stratified squamous epithelium
34
What is the function of keratinocytes located in the epidermis
Protect and function as a barrier against vitamin D production
35
Where are stem cells located in the epidermis
Stratum basale
36
What is the function of stem cells in the epidermis
Self renewal and repopulation of the epidermis
37
Where are merkel cells located in the epidermis
In mainly the basal layer
38
What is the function of merkel cells in the epidermis
Sensation
39
Where are langerhan cells located in the epidermis
Mainly in the stratum spinosum and the upper dermal layer
40
What is the function of langerhan cells in the epidermis
Dendritic cells and antigen presentation - phagocytosis
41
Where are melanocytes located in the epidermis
Basal layer
42
What is the function of melanocytes
Protection from radiation
43
Which two cells in the epidermis have larger extending cell processes
Langerhan cells and melanocytes
44
Name the 7 molecules located in the epidermis
Keratin Profilaggrin Involucrin Ioricrin Polysaccharides Glyproteins Lipids
45
Where are keratin molecules located in the epidermis
In all epidermal layers - stratum basale, stratum spinosum, stratum granulosum, stratum corneum
46
Where are profillaggrin, ioricrin and involucrin located in the epidermis
Keratohyalin granules
47
What is the function of profilaggrin
Converted to filaggrin which aggregates keratin filaments into tight bundles
48
What is the function of involucrin
Formation of cell envelope around cells in the stratum corneum
49
What is the function of iocrin
Cross links into involucrin
50
Where are polysaccharides, lipids and glycoproteins located in epidermis
Lamellar granules
51
What is the function of polysaccharides, glycoproteins and lipids in the epidermis
Form cement and go into the intracellular space which binds the stratum corneum cells
52
What is the dermis composed of
Supportive connective tissue
53
Name the cells junctions which connects the epidermis to the dermis
Hemidesmosomes and desmosomes which also connect to the basement membrane
54
List the function of the dermis
Provides tensile strength - collagen fibres Allows stretching - flexibility ( elastin fibres) Immune role
55
Name the two layers of the dermis
Papillary layer and the reticular layer
56
Describe the composition of the papillary layer of the dermis
Thin elastic and collagen fibres Contains small finger like projections and more blood vessels are found there
57
Describe the comments of the reticular layer of the dermis
This is attached to the subcutaneous layer Contains dense irregular connective tissue containing fibroblasts, bundles of collagen and elastin fibres Contains adipose tissue, hair follicles, nerves, sebaceous oils glands, sweat glands and erector pilo muscle and vascular plexsus
58
List the cells found in the dermis
Fibroblasts Lymphocytes Dermal dendritic cells Mast cells
59
What is the function of fibroblast cells in the dermis
Synthesis of collagen, elastin, and growth factors
60
What is the function of lymphocytes in dermis
Immunosuvelliance
61
What is the function of dermal dendritic cells in the dermis
Phagocytosis And antigen representation
62
What is the function of mast cells in the dermis
Produce inflammatory mediators, such as histamines, cytokines, chemotactic receptors for eosinophils and neutrophils
63
List 3 of the adenexel structures
Glands Nails Hair
64
What are the 3 types of glands found in the skin
Eccrine Apocrine Sebaceous
65
Explain the function of eccrine glands
Temperature controlling glands - sweating Not on nail beds, lips, external auditory canal and some areas of genitalia Located mainly of axillae, palms of hands and soles
66
What is the function of apocrine glands
Scent glands - unclear role Located in the axillae and genitalia - modified, ear, eyelid and breasts
67
What is the function of sebaceous glands
Formed from hair follicles Present everywhere - NOT PALMS/ SOLES Enlarge at puberty in response to androgens and provide lipids which lubricate hair shaft
68
Describe the nail plate as an adenexal structure
Modified version of stratum corneum and provides a laminated keratinised structure overlying the nail bed matrix.
69
Describe the structure of hair follicles in the epidermis
Hair follicles are tubular invagination of the epidermis downwards towards the epidermis and dermis
70
How does hair grow from the epidermis
Initially develops from the hair bulb proliferating upwards which gradually becomes keratinised to produce hair. Hair colour is determined by melanin
71
List the 3 molecules in the dermis
Collagen type 1 Elastin Proteoglycans/ glycosaminoglycans
72
Describe the function of collagen type 1 in the dermis
Major structural fibrous proteins
73
Describe the function of elastin in dermis
Confers elasticity and recoiling properties
74
Describe the function of proteoglycans and glycosaminoglycans
Hydration and other functions
75
Describe composition of the layer underneath the dermis
Hypodermis - composed of fat and loose connective tissue. Provides the skin with stability and makes sure the underlying structures are good. Most of the fat cells are found in the hypodermis. Adipose tissue - helps reduce heat loss, absorbs shock and acts as an energy reserve.
76
How does excessive UV expose effect the skin
Increases fragility Reduces elasticity Abnormal pigmentation Haemorrhage of blood vessels Wrinkles and premature ageing
77
Where is melanin synthesised in the skin
Melanosomes in melanocytes
78
How are is melanin transferred around the body
By keratinocytes through cytoplasmic processes
79
What is a wound
Breakdown in the protective function of the skin with or without the loss of connective tissue
80
Describe an erosion wound
Only the epidermis is lost
81
Describe an ulceration wound
Structures which are deep to the epidermis are effected
82
Describe a partial thickness wound
Some of the dermis and epidermis are affected The adenexel structures function as a resevoir for for epithelial cells to repopulate the wound.
83
Describe a full thickness wound
The epidermis and all of the dermis including some deeper structures with the wound only only healing through the edge of the cells ,
84
Name the 3 phases of wound healing in order
Inflammatory phase Proliferative phase Remodelling phase
85
Describe the process of the inflammatory phase
- occurs between 24/ 48 hrs - the site of injury attracts platelets which causes them to aggregate and produce a blood clot. -healing cascade and clot formation attract neutrophils and macrophages to the wound site which promotes the production of different growth factors - - growth factors which help heal the wound site include - platelet derived growth factor, vascularise endothelial growth factor, fibroblast growth factor, angiotensin promoting growth factor. - macrophages and neutrophils also engulf any pathogens or bacteria which can cause further infection. Wound site also displays signs of inflammation including swelling, heat, pain and redness
86
Describe the process of to proliferative phase
- Wound becomes a scab and cells beneath the scab migrate - fibroblasts help produce scar tissue through glycoproteins and collagen fibres bridging - damaged blood vessels begin to regrow through angiogenesis ( development of surrounding blood vessels which supply the tissue) - granulation tissue begins to fill the wound Proliferative phase takes between 1-2 days which allows for epithelial cell-cell adhesions and migrate to the wound site. This is then covered by granulation tissue which meets in the middle understate the scab and forms a bridge. Single layer of keratinocytes which cover the wound promotes the proliferation of more keratinocytes at the wound. This forms granulation tissue and collagen type 3.
87
Describe the process of the remodelling phase
Granulation tissue becomes mature scar tissue Elasticity of skin only reaches 70% Collagen in arranged into thicker bundles which is cross linked forming mature scar tissue Type 3 collagen in converted into type 1 collagen
88
What is the function of epidermal growth factor [EPG]
Re- epithelialisation and proliferation of keratinocytes
89
Describe the function of platelet derived growth factor (PDGF)
Formation of matrix through increased production of fibroblasts Remodelling ( production of proteases)
90
Describe the function of vascular endothelial growth factor (VEGF)
Angiogenesis ( migration and proliferation of endothelial cells)
91
Name the cytokines which are released due to inflammation at the wound
IL6, IL1 and tNF a
92
List some of the local factors which affect wound healing
Oxygenation Infection Foreign body Vascular supply
93
List some of the systemic factors which affect wound healing
Age Disease Alcohol Smoking Immunocompromised condition Obesity Medication - glucocorticoid steroids

Week 1 - Cells & Organelles (5 decks)

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