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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
Q

What is the composition of stratum granulosum layer in epidermis

A

The cells become flattened as they loose their nucleus and cytoplasm
Contain keratipohyalin granules

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26
Q

Name the layer of the epidermis which is above stratum granulosum

A

Stratum corneum

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27
Q

Describe the composition of stratum corneum layer

A

Large flat plate like envelopes filled with cross link keratin and lipids

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28
Q

Name the layer which connects the dermis with the epidermis

A

Basement membrane

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29
Q

List the layers of the epidermis in order

A

Basement membrane
Stratum basale
Stratum spinosum
Stratum granulosum
Stratum corneum

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30
Q

Which layer of the epidermis is found on thicker parts of the skin such as the foot or the palms of the hand

A

Stratum lucidum

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31
Q

Describe the composition of stratum lucidum

A

Layer of dead skin cells which provides protection to areas such as the sole of the foot or palms of the hand

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32
Q

Name the 5 cells found in the epidermis

A

Keratinocytes
Merkel cells
Langerhan cells
Melanocytes

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33
Q

Where are keratinocytes located in the dermis

A

Keratinised stratified squamous epithelium

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34
Q

What is the function of keratinocytes located in the epidermis

A

Protect and function as a barrier against vitamin D production

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35
Q

Where are stem cells located in the epidermis

A

Stratum basale

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36
Q

What is the function of stem cells in the epidermis

A

Self renewal and repopulation of the epidermis

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37
Q

Where are merkel cells located in the epidermis

A

In mainly the basal layer

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38
Q

What is the function of merkel cells in the epidermis

A

Sensation

39
Q

Where are langerhan cells located in the epidermis

A

Mainly in the stratum spinosum and the upper dermal layer

40
Q

What is the function of langerhan cells in the epidermis

A

Dendritic cells and antigen presentation - phagocytosis

41
Q

Where are melanocytes located in the epidermis

A

Basal layer

42
Q

What is the function of melanocytes

A

Protection from radiation

43
Q

Which two cells in the epidermis have larger extending cell processes

A

Langerhan cells and melanocytes

44
Q

Name the 7 molecules located in the epidermis

A

Keratin
Profilaggrin
Involucrin
Ioricrin
Polysaccharides
Glyproteins
Lipids

45
Q

Where are keratin molecules located in the epidermis

A

In all epidermal layers - stratum basale, stratum spinosum, stratum granulosum, stratum corneum

46
Q

Where are profillaggrin, ioricrin and involucrin located in the epidermis

A

Keratohyalin granules

47
Q

What is the function of profilaggrin

A

Converted to filaggrin which aggregates keratin filaments into tight bundles

48
Q

What is the function of involucrin

A

Formation of cell envelope around cells in the stratum corneum

49
Q

What is the function of iocrin

A

Cross links into involucrin

50
Q

Where are polysaccharides, lipids and glycoproteins located in epidermis

A

Lamellar granules

51
Q

What is the function of polysaccharides, glycoproteins and lipids in the epidermis

A

Form cement and go into the intracellular space which binds the stratum corneum cells

52
Q

What is the dermis composed of

A

Supportive connective tissue

53
Q

Name the cells junctions which connects the epidermis to the dermis

A

Hemidesmosomes and desmosomes which also connect to the basement membrane

54
Q

List the function of the dermis

A

Provides tensile strength - collagen fibres
Allows stretching - flexibility ( elastin fibres)
Immune role

55
Q

Name the two layers of the dermis

A

Papillary layer and the reticular layer

56
Q

Describe the composition of the papillary layer of the dermis

A

Thin elastic and collagen fibres
Contains small finger like projections and more blood vessels are found there

57
Q

Describe the comments of the reticular layer of the dermis

A

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
Q

List the cells found in the dermis

A

Fibroblasts
Lymphocytes
Dermal dendritic cells
Mast cells

59
Q

What is the function of fibroblast cells in the dermis

A

Synthesis of collagen, elastin, and growth factors

60
Q

What is the function of lymphocytes in dermis

A

Immunosuvelliance

61
Q

What is the function of dermal dendritic cells in the dermis

A

Phagocytosis
And antigen representation

62
Q

What is the function of mast cells in the dermis

A

Produce inflammatory mediators, such as histamines, cytokines, chemotactic receptors for eosinophils and neutrophils

63
Q

List 3 of the adenexel structures

A

Glands
Nails
Hair

64
Q

What are the 3 types of glands found in the skin

A

Eccrine
Apocrine
Sebaceous

65
Q

Explain the function of eccrine glands

A

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
Q

What is the function of apocrine glands

A

Scent glands - unclear role
Located in the axillae and genitalia - modified, ear, eyelid and breasts

67
Q

What is the function of sebaceous glands

A

Formed from hair follicles
Present everywhere - NOT PALMS/ SOLES

Enlarge at puberty in response to androgens and provide lipids which lubricate hair shaft

68
Q

Describe the nail plate as an adenexal structure

A

Modified version of stratum corneum and provides a laminated keratinised structure overlying the nail bed matrix.

69
Q

Describe the structure of hair follicles in the epidermis

A

Hair follicles are tubular invagination of the epidermis downwards towards the epidermis and dermis

70
Q

How does hair grow from the epidermis

A

Initially develops from the hair bulb proliferating upwards which gradually becomes keratinised to produce hair.

Hair colour is determined by melanin

71
Q

List the 3 molecules in the dermis

A

Collagen type 1
Elastin
Proteoglycans/ glycosaminoglycans

72
Q

Describe the function of collagen type 1 in the dermis

A

Major structural fibrous proteins

73
Q

Describe the function of elastin in dermis

A

Confers elasticity and recoiling properties

74
Q

Describe the function of proteoglycans and glycosaminoglycans

A

Hydration and other functions

75
Q

Describe composition of the layer underneath the dermis

A

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
Q

How does excessive UV expose effect the skin

A

Increases fragility
Reduces elasticity
Abnormal pigmentation
Haemorrhage of blood vessels
Wrinkles and premature ageing

77
Q

Where is melanin synthesised in the skin

A

Melanosomes in melanocytes

78
Q

How are is melanin transferred around the body

A

By keratinocytes through cytoplasmic processes

79
Q

What is a wound

A

Breakdown in the protective function of the skin with or without the loss of connective tissue

80
Q

Describe an erosion wound

A

Only the epidermis is lost

81
Q

Describe an ulceration wound

A

Structures which are deep to the epidermis are effected

82
Q

Describe a partial thickness wound

A

Some of the dermis and epidermis are affected

The adenexel structures function as a resevoir for for epithelial cells to repopulate the wound.

83
Q

Describe a full thickness wound

A

The epidermis and all of the dermis including some deeper structures with the wound only only healing through the edge of the cells ,

84
Q

Name the 3 phases of wound healing in order

A

Inflammatory phase
Proliferative phase
Remodelling phase

85
Q

Describe the process of the inflammatory phase

A
  • occurs between 24/ 48 hrs
  • the site of injury attracts platelets which causes them to aggregate and produce a blood clot.

  • 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
Q

Describe the process of to proliferative phase

A
  • 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
Q

Describe the process of the remodelling phase

A

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
Q

What is the function of epidermal growth factor [EPG]

A

Re- epithelialisation and proliferation of keratinocytes

89
Q

Describe the function of platelet derived growth factor (PDGF)

A

Formation of matrix through increased production of fibroblasts
Remodelling ( production of proteases)

90
Q

Describe the function of vascular endothelial growth factor (VEGF)

A

Angiogenesis ( migration and proliferation of endothelial cells)

91
Q

Name the cytokines which are released due to inflammation at the wound

A

IL6, IL1 and tNF a

92
Q

List some of the local factors which affect wound healing

A

Oxygenation
Infection
Foreign body
Vascular supply

93
Q

List some of the systemic factors which affect wound healing

A

Age
Disease
Alcohol
Smoking
Immunocompromised condition
Obesity
Medication - glucocorticoid steroids

Week 1 - Cells & Organelles (5 decks)

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