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Dermatology > Structure and Function 1 and 2 > Flashcards

Structure and Function 1 and 2 Flashcards

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Dermatology Board Prep flashcards
1
Q

What are the two layers of the skin? Which is external and which is internal? When do they come together?

A

Epidermis (external) and dermis (internal), they come together during embryo development

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2
Q

Which layer is thicker, the dermis or epidermis?

A

Dermis

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3
Q

What epithelial cell is the epidermis composed of?

A

Stratified squamous epithelium

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4
Q

What is the dermis composed of?

A

Leathery, fibrous connective tissue

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5
Q

Where is the epidermis embryologically derived from?

A

Ectoderm

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6
Q

How is the epidermis embryologically formed?

A

Forms a single layer periderm which gradually increases in the number of cells until they cast off

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7
Q

Where is the dermis embryologically derived from?

A

Mesoderm

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8
Q

Where is the mesoderm in relation to the ectoderm?

A

Below

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9
Q

In relation to skin development, what happens at 4 weeks?

A

The periderm, basal layer and dermis are formed

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10
Q

When does gastrulation occur?

A

Days 7-10

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11
Q

In relation to skin development, what happens at 16 weeks?

A

The layers of the epidermis are formed

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12
Q

In relation to skin development, what happens at 26 weeks?

A

Skin appendages are formed

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13
Q

What do Blascko’s lines show?

A

The developmental growth pattern of skin

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14
Q

Do Blascko’s lines follow vessels, nerves or lymphatics?

A

No

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15
Q

What does it indicate if Blascko’s lines show up on a child?

A

A congenital fault where something went wrong with the migration of cells during development

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16
Q

What makes up 95% of cells in the epidermis?

A

Keratinocytes

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17
Q

Describe the differentiation of cells in the epidermis?

A

Cells move upwards from the basal layer which allows continuous regeneration of the epidermis, with one cycle taking around 28 days

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18
Q

How many layers are there of the epidermis?

A

4

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19
Q

Give three examples of specialised cells found in the epidermis?

A

Melanocytes, Merkel cells, Langerhans cells

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20
Q

Are the contents of the epidermis consistent all over the body?

A

No, they vary depending on the site

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21
Q

How does the epidermis reversibly react to mechanical pressure?

A

Produces more keratin

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22
Q

What are three things which control epidermal cell turnover?

A

Growth factors, cell death and hormones

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23
Q

Control of epidermal cell turnover is lost in what diseases?

A

Psoriasis and skin cancer

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24
Q

How long does epidermal cell turnover take in psoriasis? Problems with differentiation in psoriasis lead to the loss of which epidermal layer?

A

4-5 days

No granular layer

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25
Q

What are the layers of the epidermis from inner to outer?

A
  • Basal cell
  • Prickle cell
  • Granular
  • Keratin
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26
Q

Which layer of the epidermis is made up essentially of stem cells?

A

Basal cell layer

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27
Q

Describe the basal cell layer?

A

Usually one cell thick, small and cuboidal with lots of intermediate filaments. It is highly metabolically active.

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28
Q

Describe the prickle cell layer?

A

Larger polyhedral cells which contain lots of desmosomes and intermediate filaments to hold the cells together

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29
Q

How many layers of cells does the granular layer have?

A

2-3 layers of flatter, granular cells

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30
Q

What are the two structural proteins found in the granular layer? What is their function?

A

Filaggrin and involucrin- important in protecting the water barrier

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31
Q

The water barrier of the epidermis is lost in what disease?

A

Eczema

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32
Q

What is the lipid content of the granular layer?

Are there nuclei present?

A

High lipid content

No nuclei

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33
Q

What cells is the keratin layer composted of?

A

Corneocytes

34
Q

What are corneocytes?

A

Terminally differentiated keratinocytes

35
Q

The keratin layer can also be known as what?

A

Stratum corneum

36
Q

Describe the keratin layer?

A

80% keratin and filaggrin with lamellar granules releasing lipids to form a tight waterproof barrier

37
Q

HPV infection of keratinocytes causes what?

A

Viral warts

38
Q

Which layer of the epidermis looks like flat slabs?

A

Keratin

39
Q

Apart from skin, what other structure can be implicated in skin disease?

A

Mucosal membranes

40
Q

In the oral mucosa, which of the masticatory/lining mucosa is keratinised?

A

Masticatory

41
Q

What three other cells can be found in the epidermis which are not keratinocytes?

A
  • Melanocytes
  • Langerhans Cells
  • Merkel Cells
42
Q

Are melanocytes found basal, supra basal or both?

A

Both

43
Q

Are Langerhans cells found basal, supra basal or both?

A

Supra basal

44
Q

Are Merkel cells found basal, supra basal or both?

A

Basal

45
Q

Where are melanocytes embryologically derived from? When do they join up with the epidermis?

A

Derived from the neural crest, transfer to the epidermis in the first 3 months of foetal development

46
Q

What type of cells are melanocytes?

A

Pigment producing dendritic cells

47
Q

What are the specialised organelles found within melanocytes? What do they do?

A

Melanosomes- convert tyrosine into melanin

48
Q

What colour is eumelanin?

A

Black/brown

49
Q

What colour is phaeomelanin?

A

Red/yellow

50
Q

What happens once melanin has absorbed light?

A

Melanin granules (full melanosomes) are transferred to adjacent keratinocytes to form a protective cap over the nucleus to protect the DNA and basal stem cells from UV light

51
Q

What is vitiligo?

A

An autoimmune disease causing immune destruction of melanocytes

52
Q

How can vitiligo be treated? What is the risk of this?

A

UV phototherapy to block the function of the immune cells which are destroying the melanocytes
If the melanocytes are stimulated this can cause melanoma

53
Q

What is albinism?

A

Genetic partial loss of pigment production

54
Q

What is Nelson’s Syndrome?

A

Melanin stimulating hormone is produced in excess by the pituitary gland, most likely because of a pituitary adenoma

55
Q

What is a malignant melanoma?

A

A tumour of the melanocyte cell line

56
Q

Where do Langerhans cells originate from?

A

Bone marrow

57
Q

Where are Langerhans cells found?

A

Prickle cell layer of the epidermis as well as the dermis and lymph nodes

58
Q

What is the function of Langerhans cells?

A

Antigen presenting cells- they pick up the antigen in the skin and then circulate it back to lymph nodes via the lymphatics

59
Q

What is the specific racket organelle found in Langerhans cells known as? What is its function?

A

Birbeck granules- they have no known function

60
Q

Where are Merkel cells found?

A

Basal, between keratinocytes and nerve fibres

61
Q

What is the function of Merkel cells?

A

Mechanoreceptors forming a connection between the skin and brain

62
Q

Where do Merkel cells originate from embryologically?

A

Mesoderm

63
Q

What is Merkel cell cancer?

A

A neuroendocrine carcinoma which is rare and caused by a viral infection- there is no cure

64
Q

Are hair follicles in the epidermis, dermis or both?

A

Both, the papilla is in the dermis

65
Q

What gland is always associated with hair follicles?

A

Sebaceous glands

66
Q

What always comes with a sebaceous gland?

A

A grease sac

67
Q

Where does hair pigment come from?

A

Melanocytes above the dermal papilla

68
Q

Where is hair embryologically derived from/

A

Ectoderm

69
Q

What is the muscle which allows hairs to stand up known as?

A

Arrector pili muscle

70
Q

What are the 3 stages of growth of hair follicles?

A

Anagen- growing
Catagen- involuting
Telogen- resting

71
Q

What are the lengths of the three periods of growth of hair?

A

They vary, with the exception of catagen which always lasts 4 weeks

72
Q

What hormones may influence hair growth?

A

Thyroxine, androgens

73
Q

Is it normal for humans hairs to enter the stages of growth at the same time? What is it called if this occurs?

A

No- telogen effluvium

74
Q

What is the most common cause of hair loss in humans? Is it reversible?

A

Telogen effluvium- yes it is reversible

75
Q

What is alopecia areata?

A

Autoimmune hair loss condition where the follicles are attacked by the immune system

76
Q

What is virilisation?

A

The development of male physical characteristics in a women or precociously in a boy due to excess androgens

77
Q

What is hirsutism?

A

Secretion of excess androgens causing excessive male pattern hair growth in females

78
Q

What is the growth rate of nails?

A

0.1mm/day

79
Q

When do nails grow faster, winter or summer?

A

Summer

80
Q

If a part of the nail is crumbly what does this mean/

A

There has been trauma at the matrix under the nail and loss of stem cells

Dermatology (15 decks)

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