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Human Epithelial Biology > Introduction to the Integumentary System > Flashcards

Introduction to the Integumentary System Flashcards

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1
Q

What is the function of the skin?

A
  • Secretion e.g. sweat and smell
  • Absorption
  • Protection
  • Sensory
  • Appearance
  • Body temperature control
  • Blood reservoir
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2
Q

What are the 3 layers of the skin?

A

Epidermis
Dermis
Hypodermis

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3
Q

What are the characteristics of the epidermis?

A
  • Epithelial
  • Non-vascular
  • Protective
  • Outermost layer
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4
Q

What are the characteristics of the dermis?

A
  • Vascular
  • Fibrous connective tissue
  • Epithelial gland structures e.g. sebaceous glands and sweat glands
  • Smooth muscle
  • Sensory
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5
Q

Describe the vasculature of the dermis

A

It is capillaries which have extended upwards from large blood vessels within the hypodermis
Provides skin pigmentation

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6
Q

Function of connective tissue in the dermis

A

holds the skin together

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7
Q

Function of smooth muscle in the dermis

A

attached to smooth muscle which when it contracts causes goose bumps
Provides the pungent smell of animals as a defence mechanism

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8
Q

What is the sensory purpose in the dermis?

A

Allows the detection of pressure, temperature etc.

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9
Q

What are the characteristics of the hypodermis?

A
  • Not skin
  • Protective
  • Adipose and loose
  • Connective tissue
  • Vascular
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10
Q

What is the function of connective tissue in the hypodermis?

A

Strength

A base structure for the dermal attachment

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11
Q

What is the 5 layers of the epidermis?

A
  • Stratum basale
  • Stratum spinosum
  • Stratum granulosum
  • Stratum lucidum
  • Stratum corneum
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12
Q

Describe the stratum basale

A
  • Bottom layer of the epidermis
  • Contacts the dermis
  • made mainly of keratinocytes
  • Has specialised epithelium and immune cells
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13
Q

Describe the stratum spinosum

A

Has weakly differentiated keratinocytes which express the karatin fibres and lamellar bodies

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14
Q

What are keratohyalin?

A

Keratinocytes which have gone to their next stage of differentiation

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15
Q

Describe the stratum granulosum

A

Keratohyalin and a hard protein envelope form

Lamellar bodies release lipids and cells die

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16
Q

Describe the stratum lucidum

A

Dead cells containing dispersed keratohyalin’s

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17
Q

Describe the stratum corneum

A

Dead cells with a hard protein envelope

The cells contain keratin and are surrounded by lipids

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18
Q

What is a keratinocyte?

A

A cell which is involved in wound healing due to its stem cell properties
Primary cell of the epidermis
It produces keratin

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19
Q

Where are keratinocytes formed?

A

Stratum basale

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20
Q

How do keratinocytes move to the surface

A

mitosis

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21
Q

How are keratinocytes connected to one another?

A

desmosomes

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22
Q

When is keratin produced?

A

as cells migrate

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23
Q

what is the function of filaggrin?

A

causes keratin to dimerise (keratinisation)

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24
Q

If a wound bleeds what does this mean and what is the function of keratinocytes?

A

You have cut the dermis

Keratinocytes heal the wound and they recruit immune cells to remove pathogens

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25
Q

How are the squamous epithelium made?

A

Through the binding of keratin and filaggrin

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26
Q

Within normal cells, what is the process of skin production

A

1) Within the stratum granulosum - profilaggrin is cleaved to small peptides
2) Filaggrin binds to keratin fibres causing cell flattening to squamous epithelium
3) Stratum corneum - keratin fibres tightly bound. Filaggrin degrades to hydrophobic amino acids and maintains skin moisture.
4) Intact barrier - prevention against pathogens

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27
Q

Within aczema patients, how is skin formed?

A

1) Filaggrin mutations reduce the amount of filaggrin in the skin
2) Keratin fibres do not form a dense, flattened barrier
3) Cracks in the skin barrier enable allergens and pathogens to penetrate dermis
4) Inflammation occurs causing irritation in the skin and other organs

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28
Q

How is eczema linked to asthma?

A

Due to the breakage in the skin, there is a higher chance of pathogens entering the skin

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29
Q

What can be used to reduce eczema-induced asthma?

A

Barrier creams

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30
Q

Function of melanocytes

A

produce pigment, melanin

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31
Q

How does melanin work?

A

Within the stratum basale, transfer of melanin to keratinocytes causes melanin accumulation to protect the nucleus from UV

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32
Q

What are merkel cells?

A

Neuroepithelial cells associated with sensory nerve endings

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33
Q

What receptor does merkel cells act on?

A

Mechanoreceptors

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34
Q

What is the neurotransmitter of merkel cells?

A

Glutamate

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35
Q

What are merkel cells sensitive to?

A

shear and pressure through desmosomal junctions

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36
Q

What are langerhan’s cells?

A

Epidermal dendritic cells

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37
Q

where are langerhan’s cells made?

A

Bone marrow

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38
Q

Where do langerhan’s cells migrate to?

A

Epidermis

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39
Q

What is the function of langerhan’s cells?

A

Function as macrophage-like antigen presenting cells (activate T cells) - the skin’s immune cell

40
Q

How is melanin made?

A

Conversion of tyrosine using tyrosinase

41
Q

Where is melanin made?

A

In melanocytes

42
Q

What are the two products of melanin production?

A

Eumelanin (black)

Pheomelanin (red)

43
Q

When are you likely to express eumelanin?

A

If you express dopaquinone

44
Q

When are you likely to express pheomelanin?

A

If you do not express dopaquinone

45
Q

Three types of UV

A

UVA
UVB
UVC

46
Q

Describe UVB and UVC

A
  • short wavelength
  • extremely damaging
  • causes sunburn
  • low dose
47
Q

Describe UVA

A
  • longer wavelength
  • penetrates dermis
  • promotes tanning
48
Q

Why is UVB and UVC dangerous?

A

The short wavelength means that it can penetrate the epidermis and occasionally the keratinocytes - can be carcinogenic

49
Q

Describe the process of tanning

A

UVA -> DNA damage in Dermis (mild) -> Epithelial DNA damage response -> alpha-melanocyte stimulating hormone (alphaMSH) synthesised and released from the damaged dermal cells -> Diffusion into the melanocortin receptor, MC1R -> Transcription factor (MITF) increases expression of tyrosinase -> eumelanin synthesis by melanocytes

50
Q

When is someone a darker colour?

A

When eumelanin > pheomelanin

51
Q

Why do tan’s fade?

A

Eumelanin is transported to surrounded keratinocytes and your keratinocytes are constantly regenerating

52
Q

what is MC1R

A

a G protein coupled receptor which is expressed in melanocytes cell membranes

53
Q

Where is alphaMSH produced?

A

the dermis

54
Q

What other factors dictate colouring?

A 
Bruising 
Jaundice 
Nervous Erythema 
Erythema 
Carotene
55
Q

What is carotene?

A

Produced by diet - carrots and oranges

Deposited into the stratum corneum and fatty tissue of the hypodermis

56
Q

What is erythema?

A

Re-direction of blood flow to superficial skin capillaries due to irritation, infection or part of a response to fever

57
Q

What is nervous erythema?

A

Blushing

Catecholamine induced vasodilation which pushes blood to the skin surface in well perfused areas of the skin

58
Q

What is jaundice?

A

A liver disease - releases bile pigments to blood which are deposited in the hypodermis and cornea of the eye

59
Q

What causes bruising?

A

Damage to capillaries of dermis and hypodermis causing deposits of bilirubin in skin

60
Q

What two layers provides dermal strength?

A

Papillary and Reticular

61
Q

Describe the papillary layer

A

thin, connective tissue with blood vessels

62
Q

Describe the reticular layer

A

dense, irregular connective tissue with collagen and elastin

63
Q

Why is the dermis multifunctional?

A

contains sweat glands, hair follicles, vascular and sensory components

64
Q

What cell types are in the dermis?

A
  • Epithelial cells
  • Fibroblasts
  • Macrophages
  • Mast cells
  • WBC’s
  • Smooth muscle (Arrector Pili)
65
Q

Characteristics of an endocrine secretion

A

Secretion through exocytosis
Using accompanied by fluid movement
Do not lose cytoplasm

66
Q

Example of an endocrine secretion

A

Fluid secreting cells in a sweat gland

67
Q

Characteristics of an apocrine secretion

A

lipid, protein and amino acid laden secretion
Contribution to scent
cells lose cytoplasm but they do not die and regenerate

68
Q

Example of apocrine secretion

A

Mammary glands

Sweat glands

69
Q

Characteristics of a holocrine secretion

A

Lipid, protein and amino acid secretions - often waxy
Thicker secretion responsible for pungent scent
Entire cell ruptures
Continual cell growth and replacement

70
Q

What are the two major components of the eccrine sweat glands?

A

Secretory coil

Re-absorptive duct

71
Q

What happens in the secretory coil?

A

1) CFTR driven Cl- secretion (blood to lumen)
2) Na+ follows via paracellular route
3) Causes an isotonic solution
4) Water moves into duct via aquaporin channels

72
Q

What happens in the re-absorptive coil?

A

1) ENaC driven Na+ absorption
2) Cl- moves through CFTR or paracellular channels to the blood
3) No aquaporins for water movement
4) Hypotonic sweat produced

73
Q

Where are apocrine glands found?

A

In armpits and anogenital regions

74
Q

Where do the apocrine glands empty?

A

Into hair follicles and mix secretions with sebaceous oils and other secretions on the skin surface

75
Q

Where do sebaceous glands empty?

A

Into a hair follicle shaft

76
Q

What is the function of the sebaceous glands?

A

Waterproofs and lubricates the skin and hair

77
Q

What does sebaceous glands secrete?

A

acid mantle

78
Q

Condition associated with sebaceous glands?

A

Acne

79
Q

What are ceruminous glands?

A

modified apocrine gland

80
Q

Where are ceruminous glands secreted?

A

onto guard hairs in the ear, producing ear wax

81
Q

What do mammary glands produce?

A

Milk

82
Q

What is a mammary gland?

A

Either a modified apocrine gland or sebaceous gland

83
Q

What are the 5 types of skin glands?

A
  • Eccrine sweat glands
  • Apocrine glands
  • Sebacous glands
  • Ceruminous glands
  • Mammary glands
84
Q

What is hair composed of?

A

Keratin secreted from hair follicle stem cells

85
Q

What is hair involved in?

A

Thermoregulation

Protection of the epidermis from UV, abrasions and bites

86
Q

What are the 3 phages of hair formation?

A

Telogen (rest)
Anagen (Growth)
Catagen (cessation)

87
Q

What controls growth of hair follicles?

A

Bone morphometric protein (BMP) - a growth factor

88
Q

What are nails made from?

A

composed of keratin secreted from the epidermal cells in the root nail

89
Q

Function of nails?

A

Protect fingertips and toes from damage

Aids in the precision of movement

90
Q

What pathway does BMP control hair growth through?

A

Winglet pathway (Wnt7b)

91
Q

What does the Wnt7b pathway control?

A

Release of beta-catenin from the adherence junction and it’s ability to go to the nucleus and drive cell cycle activity

92
Q

What happens in Telogen?

A

Around the base of the hair follicle, there is high concentrations of BMP

93
Q

What happens in telogen-anagen?

A

decrease levels of BMP
Deactivate Wnt7b
Activation of beta-catenin
increase in size of sebaceous glands

94
Q

What happens in the full anagen process?

A

Same process
Full keratin secretion
Growth of hair shaft
Decrease BMP

95
Q

What happens in catagen?

A

Suppression of Wnt signalling
Increase BMP
Apoptosis

Human Epithelial Biology (6 decks)

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