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Dermatology > Functional Anatomy and Physiology of the Skin > Flashcards

Functional Anatomy and Physiology of the Skin Flashcards

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Dermatology Board Prep flashcards
1
Q

Name the 4 layers of the Epidermis

A

Basal Layer, Granular Layer, Prickle cell layer and Keratin layer

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2
Q

What cell type makes up 95% of the epidermis?

A

Keratinocytes

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3
Q

What is the main proliferative compartment within the epidermis?

A

The basal layer

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4
Q

What happens at the basal layer of the epidermis?

A

The keratinocytes migrate from the basal layer to the top later. They differentiate, producing a variety of protein and lipid products

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5
Q

What is the normal time for differentiation from the basal layer to the keratin layer of the epidermis?

A

28 days

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6
Q

What are the main features of the Prickle cell layer?

A

Larger Polyhedral cells and lots of Desmosomes

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7
Q

What happens to the keratinocytes at the Granular layer of the Epidermis?

A

They undergo apoptosis

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8
Q

What are the main features of the Granular Layer?

A

Cell nuclei lost, 2-3 layers of flatter cells, high lipid content

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9
Q

What layer can you not see in psoriasis?

A

Granular layer

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10
Q

Where does terminal differentiation occur?

A

At the Keratin layer

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11
Q

How does terminal differentiation take place?

A

Filaggrin aggregates keratin filaments and causes terminal differentiation

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12
Q

What are the features of the keratin layer of the Epidermis?

A

Flattened corneocytes with no nucleus and overlapping cells which creates a tight waterproof barrier

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13
Q

What is psoriasis?

A

Ongoing, non stop phase of a wound reaction, increased production of skin cells

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14
Q

What is the difference in time for normal differentiation and psoriasis?

A

Normal: 28 days
Psoriasis: 4-5 days

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15
Q

How does intraepidermal blisters arise?

A

Lots of hydrostatic water pushes apart the desmosomes within the Prickle cell layer, forming a huge dome

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16
Q

How is the regulation of epidermal turnover controlled?

A

By growth factors, cell death and hormones

or Loss in control in: skin cancer and psoriasis

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17
Q

What are the skin appendages?

A

Nails, hair, mucosae, glands

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18
Q

Name 3 other major types of cell within the epidermal layer

A

Melanocytes, Langerhans cells, Merkel cells

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19
Q

What happens at the melanocytes?

A

The Melanin pigment is synthesised from Tyrosine–> Melanin absorbs light–> Full Melanocomes are transferred to adjacent keratinocytes via dendrites

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20
Q

Name two of the melanin pigments in the Melanocytes

A

Euchelanin (brown or black)

Phaeomelanin (red or yellow)

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21
Q

What is the function of melanin caps?

A

To protect the nuclear DNA in the basal cells

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22
Q

What is the role of the Langerhans cells in the Epidermal layer?

A

They are involved in the skin immune system, in the antigen presentation to lymphocytes
They circulate between the epidermis and the lymph nodes

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23
Q

What are Birbeck granules?

A

Organelles within the Langerhans cells with an unknown function

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24
Q

Where are Langerhans cells found in the epidermis?

A

Dispersed at the prickel cell level, very densely packed together

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25
Q

What are Merkel cells?

A

Mechanoreceptors which are found in the basal layer

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26
Q

What happens to Merkel cells in diabetes patients?

A

Merkel cells are myelinated–>
Diabetes affects the myelin sheaths, glucose disrupts the protein arrangement and the sheath no longer conducts–>
This causes paraethesia or itchiness

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27
Q

What can affect the Merkel cells?

A

A specific viral infection which has a high mortality rate

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28
Q

Where are the Merkel cells?

A

In the basal layer

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29
Q

What is Vitiligo?

A

An autoimmune disease with loss of melanocytes

  • “white spot disease:
  • constant and active loss of melanocytes
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30
Q

What is Albinism?

A

Genetic partial loss of pigment production

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31
Q

What is Nelson’s syndrome?

A

Melanin stimulating hormone is produced in excess by the pituitary

32
Q

What is Virilisation?

A

Excess hair on women (facial hair etc) due to excess androgen from a tumour

33
Q

What is Alopecia Areata?

A

An autoimmune condition which caused hair loss. Can be triggered by massive psychosocial stress such as bereavement or pregnancy

34
Q

What can you look at as a sign of internal inflammation?

A

Nails

35
Q

During the hair cycle what do these phases refer to, and for how long dot they last?:

  • Anagen
  • Catagen
  • Telogen
A
  • Anagen: growing (years)
  • Catagen: transitional (a few days)
  • Telogen: resting phase (3 months)
36
Q

What is the difference between lanugo hair and vellum hair?

A

Lanugo: newborns and non pigmented
Vellus: similar to lanugo but pigmented

37
Q

Why do we have lots of hair?

A

To reduce the need to have melanin and melanocytes

38
Q

What are the three layers of the Dermo-epidermal junction?

A
  • Lamina lucida
  • Lamina densa
  • Sublamina densa
39
Q

What are some of the components of the dermis?

A
  • 75% collagen
  • 1% elastin
  • mast cells, langerhans, blood vessels, lymphatics, ground substance, T lymphocytes
40
Q

What is the function of the basement membrane?

A

allows the movement of cells and nutrients between the dermis and epidermis

41
Q

How are the cell membrane of the epidermal basal cell and the basement membrane attached?

A

By hemi-desmosomes

42
Q

What is present at the DEJ?

A

Proteins, fibrils and keratins

43
Q

What happens to the DEJ during old age?

A

Becomes flatter

-wrinkles are caused by tired elastic

44
Q

What does smoking and UV do to the DEJ?

A

depletes the collagen

45
Q

What happens in inherited diseases of the DEJ?

A

Skin fragility due to a mutation in one of the proteins

46
Q

Give examples of inherited diseases of the DEJ

A

Epidermolysis bullosa simplex or dystrophic

47
Q

Give an examples of an acquired disease of the DEJ

A

Bullous Permohigoid

  • Type 2 hypersenstivity reaction
  • formation of anti-hemidesmosome antibodies
  • treated with steroids
48
Q

What is Meissner’s corpuscle?

A
  • Dermis nerves

- Touch receptors in the fingertips

49
Q

What is Pacinian Corposcle?

A
  • Dermis nerves

- Pressure receptors

50
Q

What can chronic lymphoedema be seen as?

A

“Elephantism”

51
Q

What is the function of the lymphatic vessels of the dermis?

A

Continual drainage of plasma proteins, extravasated cells and excess interstitial fluid

52
Q

What are the three main skin glands in the dermis?

A
  • Sebaceous
  • Eccrine
  • Apocrine
53
Q

What do Eccine glands do?

A
  • Whole body sweat glands
  • None in groin and mouth
  • Cools by evaporation
54
Q

What do Apocrine glands do?

A
  • In axillary and groin
  • Produce oily fluid
  • Odour
55
Q

What do Sebaceous glands do?

A
  • Produces sebum
  • Activated during puberty
  • Moisture control
  • Opens onto hair follicle
  • High concentration on face and back
56
Q

Name the main functions of the skin

A

Barrier function, metabolism and detoxification, thermoregulation, immune defence, communication, sensory functions

57
Q

What is Toxic Epidermal Necrolysis?

A

Acute skin failure, usually caused by a reaction to drugs

-rare and life threatening

58
Q

What is erthyroderma?

A

Another type of acute skin failure, red skin all over 80-90% of the body

  • skin peeling off in layers
  • can be due to a number of conditions such as dermatitis, psoriasis and T cell lymphoma
59
Q

How can statins cause dry skin?

A
  • Lowers cholesterol

- skin is made up of “brick and mortar” with brick being keratin and mortar cholesterol

60
Q

In dermatitis, if the skin between the fingertips is affected what is it more likely to be?

A

Irritancy

61
Q

What is the function of melanocytes?

A

Absorb UV rays

62
Q

How is vitamin D3 produced?

A

By photosynthesis

63
Q

How is vitamin D stored and converted?

A

D3 is stored as hydroxycholecalciferol in liver

This is converted to 1,25-dihydroxycholecaliferol in the kidney

64
Q

What vitamin do kidney failure patients need?

A

Vitamin D

65
Q

Where is T4 metabolised to T3?

A
  • 20% conversion occurs in thyroid gland

- 80% conversion in the peripheral tissues including skin

66
Q

What is more abundant T3 or T4?

A

T4 is more abundant but less active

67
Q

What happens when body temperature decreases?

A

Blood flows from the superficial plexus

68
Q

What is Hansen’s disease?

A

TB Leprosy

Granuloma formation around peripheral nerves, causing damage due to immune response

69
Q

Name some autoimmune diseases

A

Eczema herpeticum, chronic discoid lupus erythmatous, squamous cell carcinoma

70
Q

How does the epidermis form in embryology?

A
  • Ectoderm cells form single layer periderm
  • There is a gradual increase in layer of cells
  • Periderm casts off
71
Q

How does the dermis form in embryology?

A

Formed from mesoderm below ectoderm

72
Q

How does the melanocytes form in embryology?

A

Pigment producing cells from the neural crest

73
Q

What does the foetal skin look like at 4 weeks?

A

Periderm, Basal layer and dermis

74
Q

What happens in the foetal skin at 16 weeks?

A

Melanocytes migrate from neural crest

75
Q

What are Blascho’s lines?

A

Developmental growth pattern of skin which doesn’t follow vessels or lymphatics

Dermatology (14 decks)

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