Physiology Flashcards

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1
Q

what is the largest organ in the body?

A

the skin

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2
Q

what are the core layers of the skin?

A
epidermis 
appendages 
derma-epidermal junction
dermis 
sub-cutis layer
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3
Q

what are the layers of the epidermis

A

keratin layer
granular layer
prickle cell layer
basal layer

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4
Q

what epithelium is the epidermis composed of?

A

stratified squamous epithelium

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5
Q

another name for the keratin layer

A

stratum corneum

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6
Q

what is the keratin layer made up of?

A

corneocytes (overlapping, non-nucleated remnants) and lamellar granules containing lipids and keratinocytes

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7
Q

function of the keratin layer

A

waterproof barrier

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8
Q

what does the granular layer consist of?

A

2-3 layers of flatten cells with keratohyalin granules that contain filaggrin and involucres protein

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9
Q

role of the granular layer

A

envelope that protects corneocytes

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10
Q

what does the prickle layer consist of?

A

larger polyhedral cells with lots of desmosomes connected to intermediate filaments

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11
Q

what does the basal layer consist of?

A

cuboidal cells with intermediate filaments
high metabolic rate
melanocytes are found here and transfer melanin via dendritic processes

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12
Q

describe epidermal turnover

A

keratinocytes migrate from the basement membrane to the stratum corneum over 28 days

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13
Q

what is epidermal turnover regulated by?

A

growth factors
cell death
hormones

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14
Q

when is epidermal control lost?

A

cancer

psoriasis (immature epidermis)

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15
Q

other cells present in the epidermis

A

melanocytes
Langerhans cells
Merkel cells

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16
Q

describe melanocytes

A

pigment-producing dendritic cells that contain melanosomes that transfer to keratinocytes via dendrites

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17
Q

role of melanocytes

A

convert tyrosine to melanin (eumelanin- brown and phaeomelanin- yellow/red)

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18
Q

what does melanin in melanocytes do?

A

absorbs sunlight forming a protective cap over the nucleus

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19
Q

which layer are langerhans cells found in?

A

prickle cell layer, dermis and lymph nodes

20
Q

what are Langerhans cells associated with?

A

birbeck granules

21
Q

where are Meckel cells located?

A

between keratinocytes and nerve fibres

22
Q

role of Meckel cells

A

mechnoreceptors

23
Q

risk in Meckel cells

A

viral cancer

24
Q

what are the three appendages present in the skin?

A

nails
hair
glands

25
Q

describe nails

A

specialised keratins

26
Q

what is hair made of

A

keratin

27
Q

what is hair attached to?

A

sebaceous gland

28
Q

how is hair colour formed

A

melanocytes above the dermal papilla

29
Q

phases of hair growth

A

anlagen
catagen
telogen

30
Q

hormonal influences on hair

A

thyroxine

androgens

31
Q

three types of glands

A

sebaceous
apocrine
eccrine

32
Q

describe sebaceous glands

A

attached to hairs
hormone sensitive and produce sebum
control moisture loss and protect from fungal infection

33
Q

describe apocrine glands

A

present in axilla and perineum

androgen dependent producing oil

34
Q

describe eccrine glands

A

whole skin surface under sympathetic cholinergic nerves

functions with ultrafiltration and thermoregulation

35
Q

describe the derma-epidermal junction

A

epithelial-mesenchymal interaction

basement membrane is laminin and collagen

36
Q

what does the dermis consist of?

A

connective tissue, fibroblasts, macrophages, mast cells, fibres and ground substances

37
Q

what fibres are in the dermis

A

collagen and elastin

38
Q

what ground substances in the dermis

A

hyaluronic acid

chondroitin sulphate

39
Q

what appendages are present in the dermis?

A

blood vessels
muscles
lymphatics
nerves

40
Q

how are the blood vessels arranged in the dermis?

A

horizontal plexuses

41
Q

what muscles are present in the dermis?

A

arrestor pili attached to hair follicles

42
Q

what lymphatics are present in the dermis

A

lymphocytes and langerhans for immune surveillance and removal of toxins

43
Q

what two types of nerves are present in the dermis

A
somatic sensory (dermatomes)
autonomic
44
Q

role of somatic sensory

A

free nerve endings with pacinian (deep pressure and vibrations) and Meissner’s (light pressure) corpuscles

45
Q

role of autonomic NS

A

supplying blood vessels, nerves and glands

46
Q

what is the sub-cutis layer made up of

A

fat

47
Q

role of the skin

A
barrier
thermoregulation
immune defence
metabolism (vitamin D and thyroxine)
communications (visual, odour, stigma)
sensation