Structure and Function Flashcards

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1
Q

what are the two layers of the skin

A

epidermis and dermis

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2
Q

what cells make up the epidermis

A

stratified squamous cells

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3
Q

where is the epidermis derived from

A

the ectoderm

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4
Q

what cells make up 95% of the epidermis

A

keratinocytes

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5
Q

what are the four defined layers of the epidermis

A

keratin
granular
prickle cell
basal

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6
Q

what is the dermis derived from

A

the mesoderm

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7
Q

What are the 4 types of epidermal cell

A

keratinocytes
melanocytes
Langerhans cells
Merkel’s cells

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8
Q

what are melanocytes and where do they originate from

A

pigment producing cells originating from the neural crest

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9
Q

what 3 layers are formed at 4 weeks of foetal skin development

A

Periderm
Basal layer
Dermis

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10
Q

by 16 weeks what are the 5 layers of skin formed

A
keratin layer 
granular layer 
prickle cell layer 
basal layer 
dermis
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11
Q

at how many weeks do hair, melanocytes and appendages form

A

26 weeks

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12
Q

what pattern does the development of skin follow

A

Blashko’s lines

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13
Q

what factors regulate epidermal turn over

A

growth factors
cell death
hormones

(loss of this control is seen in skin cancer and psoriasis)

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14
Q

How many days does it take for the epidermis to regenerate (from bottom to top)

A

28 days

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15
Q

which layer is one cell thick, has small cuboidal shaped cells, contains intermediate filaments and is highly metabolically active

A

basal layer

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16
Q

the prickle cell layer is thinner in psoriasis true/false

A

false

its thicker

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17
Q

what layer contains island bodies (secretory cells)

A

granular

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18
Q

what does the keratin layer consist of

A

corneocytes (overlapping, non-nucleated cell remnants, differentiated keratinocytes)

19
Q

what other than corneocytes does the keratin layer contain

A

cornfield envelope
keratin and filaggrin
lamellar granules (release lipids)

20
Q

where do melanocytes originate

A

neural crest (migrate to the epidermis in the first 3 month of development)

21
Q

where are melanocytes found

A

the basal layer

22
Q

what do melanocytes do

A

pigment producing dendritic cells, convert tyrosine to melanin pigment

melanin granules are transferred to adjacent keratinocytes via dendrites

form a protective cap over DNA in the basal cells to protect from UV light and hormones

23
Q

what colour is Eumelanin

A

brown or black

24
Q

what colour is Phaemelanin

A

red or yellow

25
Q

where do langerhans cells originate

A

bone marrow

26
Q

what do langerhans cells do

A

antigen presenting cells

27
Q

where are Merkel cells found

A

basal layer, on the ends of nerve fibres, direct extension of the brain

28
Q

what do merkels cells do

A

mechanoreceptors (respond to mechanical stimuli)

29
Q

what is vitiligo

A

a skin condition involving hypo pigmentation of the skin due to the melanocytes being attacked by T cells

30
Q

what is Nelson’s syndrome

A

where melanin stimulating hormone is produced in excess by the pituitary gland causing bronzing of the skin

31
Q

what are the three stages of hair growth

A

Anagen -growing
Catagen -involuting
Telogen -resting

32
Q

at what rate do nails grow

A

0.1mm per day

33
Q

what is the demo-epidermal junction and what are its functions

A

the interface between the dermis and the epidermis

provides anchorage, support, and adhesion as well as being a semi permeable membrane acting as a barrier and a filter

34
Q

What are the three layers of the demo-epidermal junction

A
Lamina Lucida (top) 
Lamina Densa (middle) 
Sub-lamina Densa (bottom)
35
Q

failure of function of the demo-epidermal junction leads to

A

fragile skin

fluid filled blisters

36
Q

what is the dermis made up of

A
ground substance (gives structure) 
collagen 
elastin 
immune cells 
blood vessels 
lymphatics 
nerves
hair follicles
37
Q

the blood supply to the skin is greater than metabolic need true/false

A

true

38
Q

what is an angioma

A

a benign overgrowth of blood vessels

39
Q

what do pancain nerves do

A

sense pressure

40
Q

what do meissners nerves do

A

sense vibration

41
Q

what causes pigmentation of hair

A

melanocytes above the papilla

42
Q

what do sebaceous skin glands produce and whats their function

A

produce oily, waxy sebum, hormone sensitive glands which control moisture and protect from fungal infections

43
Q

what do apocrine glands produce and whats their function

A

sweat glands which produce odour due to bacterial decomposition, linked to hair follicles

44
Q

what do eccrine produce whats there function

A

sweat glands occurring everywhere

not attached to hair follicle