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Dermatology > Skin Structure and Function > Flashcards

Skin Structure and Function Flashcards

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Dermatology Board Prep flashcards
1
Q

What are the 2 main layers of skin?

A

The epidermis (outer) and the dermis

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2
Q

Which germ layer is the epidermis derived from?

A

ectoderm

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3
Q

How does the epidermis form in the fetus?

A

Ectoderm cells form a single layer periderm which gradually increase in layers and before birth the periderm cells are cast off

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4
Q

What germ layer is the dermis derived from?

A

mesoderm

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5
Q

What are melanocytes derived from?

A

the neural crest

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6
Q

What are the 6 layers in skin?

A 
Keratin layer
Granular layer
Prickle cell layer
basal layer
dermis
sub-cutis
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7
Q

what are blaschkos lines?

A

developmental growth patterns of skin, which don’t follow vessels, nerves or lympathics

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8
Q

What does the skin consist of?

A

epidermis; appendages (hair, nails, glands, mucosae) ; dermo-epidermal junction; dermis and the sub-cutis

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9
Q

What does the basal layer do?

A

Divides in order to replenish the upper layers

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10
Q

How does the prickle cell layer become the granular layer?

A

It differentiates and produces lots of protein (granular- lots of proteins)

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11
Q

How does the granular layer becoem the keratin layer?

A

Releases protein in order to become flat

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12
Q

What type of epithelium is the epidermis

A

stratified squamous epithelium

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13
Q

What are the majority of the cells found in the epidermis?

A

Keratinocytes which contain structural keratins

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14
Q

What other cells are found within the epidermis?

A

Melanocytes; langerhan cells and merkel cells

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15
Q

How is epidermal turnover regulated?

A

growth factors; cell death and hormones

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16
Q

How long does it take for a keratinocytes to migrates from the basmement membrane to the top?

A

28 days

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17
Q

Describe the basal layer

A

usually one cell thick
small cuboidal
lots of intermediate filaments (keratin)
highly metabolically active

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18
Q

Describe the prickle cell layer

A

larger polyhedral cells
lots of desmosomes
intermediate filaments connect to desmosomes
(named after prickly pear appearance)

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19
Q

Describe the granular layer

A 
2-3 layers of flatter cells
large keratohyalin granules- contain structural filaggrin and involucrin proteins
odland bodies ( lamellar bodies)
high lipid content
origin of "cornified envelope"
cell nuclei lost
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20
Q

What is the cornified envelope?

A

A layer of ceramides which become covalently bonded to an envelope of structural proteins. This replaces the cell membrane during a process called cornification in which live keratinocytes become non-living corneocytes. The complex surrounds the cells and contributes to the barrier function of the skin.

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21
Q

Describe the keratin layer

A 
Made up of the corneocytes- overlapping non-nucleated cell remnants
insoluble cornified envelope
80% keratin and filagrin
lamellar granuels release lipid
TIGHT WATRETPROOF BARRIER
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22
Q

What are melanocytes?

A

pigment producing dendritic cells

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23
Q

Where are melanocytes found?

A

in the basal layer and above

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24
Q

What happens in the melanosomes?

A

tyrosine is converted to melanin pigment

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25
Q

What happens to full melanosomes (melanin granules)?

A

they are transferred to adjacent keratinocyte via dendrites

26
Q

What is the function of melanin granules?

A

form a protective cap over nucleus as they absorb light and prevent UV ray messing with the DNA in basal cells

27
Q

What is vitiligo?

A

an autoimmune disease where there is loss of melanocytes

28
Q

What is the origin of langerhan cells?

A

mesenchymal origin (bone marrow)

29
Q

Where are Langerhan cells found in the skin?

A

prickle cell level in the epidermis and in dermis (also in lymph nodes)

30
Q

What is the function of langerhan cells?

A

APCs - pick up Ag in skin and circulate to lymph nodes via lymphatics

31
Q

What is the special organelle found in langerhan cells?

A

birbeck granules/ racket organelle (looks like a tennis racket)

32
Q

Where are Merkel cells found?

A

in the basal layer between keratinocytes and nerve fibres

33
Q

What are merkel cells?

A

mechanoreceptors

34
Q

Look at picture of hair follicle and be able to name different parts of it

A 
\:)
sebaceous unit (grease bag that sits on top of muscle)
pili arrector muscle
dermal papilla
matrix
cortex
medulla
interal and external root sheaths
35
Q

What are the 3 phases of growth in a hair follicel

A

anagen- growing
catagen- involuting
telogen- resting

36
Q

What is telogen effluvium?

A

when stress pushes more hair follicles prematurely into the telogen phase (meaning more fall out)

37
Q

When does telogen effluvium most commonly occur?

A

postpartum

38
Q

How is the nail plate and the matrix of a nail connected?

A

The 3 partsof the nail plate- dorsal; intermediate and ventral all grow from the same corresponding subdivision of the matrix

39
Q

What are the functions of the dermo-epithelial junction?

A
  • support; anchorage; adhesion; growth and differentiation of basal cells
  • semi-permeable membrane acting as a barrier and filter between the epithelium and mesenchyme
40
Q

What cells are found in the dermis?

A

fibroblasts, macrohpages, mast cells, lymphocytes and langerhan cells

41
Q

what fibres are found in the dermis?

A

collagen and elastin

42
Q

Describe the blood vessels found within the dermis

A

The supply is greater than metabolic need
vessel walls are well spported
plexuses are horizontal

43
Q

What is an angioma?

A

localised overgrowth of blood vessels

44
Q

What is the somatic sensory supply of the dermis like?

A

there are:
free nerve endings
speical receptors for pressure-pacinian corpuscles and for vibration- meissners corpuscles

45
Q

Where does the pigmentation of the hair follicles take place?

A

In the melanocytes above the dermal papilla

46
Q

What are the 3 types of skin glands?

A

sebaceous; apocrine and eccrine

47
Q

Describe sebaceous glands

A 
widely distrbuted but the largest glands are in the face and chest
produce sebum
hormone sensitive (dont do anything before puberty)
48
Q

what are the functions of sebaceous glands?

A

control moisture loss and protect from fungal infections

49
Q

what is sebum made from?

A

squalene, wax esters, triglycerides and free FAs

50
Q

Decribe apocrine sweat glands

A

develop as part of pilo-sebaceous unit
found in axillae and perineum
androgen dependent
produce oily fliud- odour after bacterial decomp

51
Q

Describe eccrine sweat glands

A

whole skin surface- especailly skin, soles and axillae

sympathetic cholienrgic nerve supply

52
Q

function of eccrine sweat glands?

A

cooling by evap

moisten palms/soles to aid grip

53
Q

Why would you describe the skin as metabolically active?

A

takes part in vitamin D metabolism and thyroid hormone metabolism (which also occurs in thyroid gland-20%)

54
Q

What are the sensory functions of the skin

A

touch, pressure, vibration, pain and itch, heat and cold

55
Q

What cells carry out vitamin D metabolism?

A

keratinocytes

56
Q

Where are hemi-desmosomes found?

A

In the DEJ

57
Q

What are commonest sweat glands in the face?

A

eccrine glands

58
Q

Which hormone stimulates the sebaceous glands production of sebum?

A

androgen

59
Q

Which glands play a role in temperature regulation?

A

eccrine glands

60
Q

Which glands play a role in scent?

A

apocrine glands

Dermatology (15 decks)

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