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Human physiology > Skin > Flashcards

Skin Flashcards

1
Q

what is skin?

A

major component of the integumentary system
largest organ
forms principle interface between exetnal envrionment and internal organs

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2
Q

what are the three main layers of the skin?

A

epidermis
dermis
hypodermis

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3
Q

what are the main functions of skin in terms of protection

A

protection of internal organs from the environment
water loss
heat loss/temp regulation
microorganism protection

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4
Q

what other main functions does the skin have other that protection

A

sensation
blood reservoir
metabolic synthesis
immune system

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5
Q

what is the epidermis

A

upper most layer

stratified

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6
Q

what cells is the epidemris mainly made of

A

dead cels composed of keratin

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7
Q

what happens to cells in the epidermis?

A

replaced and are at differing stages of maturation at each layer
differentiate at the bottom and slowly move to the top gathering keratin and die at the top

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8
Q

4 cells in epidermis

A

keratin bases cell keratinocytes
pigement melanocytes
langerhans cells
merkle cells

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9
Q

what is a keratinocte

A

major part of epidermis

sent up from basal layer and differentiate

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10
Q

how does kerinatisation occur?

A

cells at the base are round
they move up and gradually get kerinatised
flattern out and die
more keratin means more protection

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11
Q

where is there more kertain in skin?

A

feed and places of high abrasion

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12
Q

function of a melanocyte

A

pigment

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13
Q

how do melanocyte work?

A

found in the basal layer and have projections out into keratinocytes to give skin tone

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14
Q

what are the two forms or melanin

A

EU: dark
PH: light

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15
Q

what is the role of melanin?

A

protection from UV

scatters it and prevents DNA damage to those cells actively dividing at the base of skin

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16
Q

what gives human skin tone variation?

A

Eumelanin

darker skins have more eumalanin

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17
Q

does everyone have the same amount of melanocyes?

A

yes

variation in tone comes fromm amount and type of melanin made not the amount of melanocytes

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18
Q

how do melanocyte give colour to skin?

A

give granules to keratinoctes
colour dependent on how keratinocytes show this
Light skin: melanin packaged into less dense graules

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19
Q

what are melanocyte granules

A

enzymes

make melanin active igment

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20
Q

what is are merkle cells?

A

neuroendorcrine cells found in the basal layer
send signals to the nervous system and can make some hormones
more in fingers and toes

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21
Q

what is the function of a Merkel cells

A

function unknown but thought to have a sensory function perhaps

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22
Q

what is a Langerhans cell?

A

dendritic antigen presenting cell which acts as an immune cell
sit in the epidermis looking for bacteria and phagocytose it

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23
Q

where do Langerhans cells come from?

A

bone marrow as monocytes and travel in the blood to epidermis

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24
Q

name the layers of the epidermis from bottom to top

A 
stratum basale  (bottom) 
stratum spinosum
stratum granulosum
stratum lucidum
stratum corneum ( top)
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25
Q

what is the stratum basale

A

stem cell layer at the bottom of the epidermis differentiated keratinocytes come from here

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26
Q

what is the stratum spinosum

A

keratinocytes begin to throw out spindles and differetiate
2-4 cells thick
langerhans found here

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27
Q

what is the stratum granulosum

A

granular tissues where cells rapidly accumulate keratin
cells begin to flatten and become thin
final layer of living cells

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28
Q

what is the stratum lucidum

A

transparent layer
only found in thick skins such as palms and feed
transitional layer to dead cells

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29
Q

what is the stratum corneum

A

top layer
dead keratinocytes
layer is thick
production and shedding rates are matched

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30
Q

features of thick skin?

A

palms and feed

stratum lucidum layer found here

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31
Q

what is the skin like in terms of microbes?

A

sterile at birth

then colonisation occurs and bacteria from the environment form a flora

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32
Q

what type of bacteria are found on the skin

A

gram positive
staphylococcus epidermis is common
no net impact largely though

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33
Q

what is the dermis?

A

papillary and retiular layers
bulk of skin
made of tough connective collgen

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34
Q

what is the reticular layer?

A

thicker layer, secondary
strength and resiliance
bundles of collagen found here
gives support

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35
Q

what is the papilary dermis?

A

thin layer adjacent to apidermis

dermal paillae create ridges

36
Q

what creates fingerprints?

A

microscopic structures called dermal papillae

they are ridges and projections into the epidermis

37
Q

where are hair and sweat glands found?

A

papillary dermis

38
Q

where is the major blood supplies for the skin

A

one in between papillar and reticular, nourished the epidermis
one between dermis and hypodermis

39
Q

what cells are there within the dermis

A

collagen
fibroblasts
dendrocytes
immune cell

40
Q

role of a fibroblast in th dermis?

A

healing
collagen making
large ER to support the making of collagen

41
Q

what is a dermal dendrocyte

A

presents antigens and contibutes to healing

42
Q

what immune cells are found in the dermis

A

macrophages
T cells
mast cells

43
Q

what can the dermis sense using neurones?

A

touch
pressure
pain
hot/cold

44
Q

three types of neuron cells within the dermis?

A

pacinian corpuscles
meissner corpulscles
Ruffini curpulscles

45
Q

what is a pacinian corpuscle

A

pressure sensitive recprot
long pressure
slow adaptive

46
Q

what is a meissner corpuscles

A

touch receptors

fast adapting

47
Q

what is a ruffini corpuscle

A

hot and cold receptor

slow adapting

48
Q

what other receptors are in the dermis?

A

thermoreceptors
pain nocicepors
proprioceptors

49
Q

how d ain nociceptors work

A

fire when noxious stimuli is detected
eg. excessive heat or cold
excessive mechanical pressure
chemicals

50
Q

how do proprioceptors work

A

sit in muscles and joints and tell where the limbs are
sense body position and joint movements
tell the brain where the limbs are without seeing them

51
Q

what does the hypodermis contain?

A

adipocytes
fat cells
connective tissue

52
Q

what cells are in the hypodermis

A

adipose tissue with fat droplets
macrophages
fibroblasts
basement mebrane

53
Q

what is a blister

A

water leaks out and is protruded into the dermis

54
Q

three component units of hair folicles

A

folicle going into dermis
sebaceous gland
papillary

55
Q

three phases of hair growth

A

anagen
catagen
telogen

56
Q

what is anagen

A

growth phase of hair

57
Q

what happens during anagen

A

stems cells actively divide, hair is extended out from the folicle base

58
Q

what makes hairs shorter than others eg hair air

A

shorter anagen stage

59
Q

what is catagen

A

atrophy stage in hair growth

60
Q

what happens during catagen

A

hair detaches from stem cell papillary layer

no longer grows, no more cells fed int it

61
Q

what is telogen

A

resting phase in hair growth

62
Q

what happens durin telogen

A

no new cells
hair fals out
new process happens again in cycle

63
Q

what causes hair shedding in mamals

A

hormones trigger atrophy and subsequent resting leading to lots of shedding of hair

64
Q

why is some hair red

A

unable to make eumelanin

65
Q

how des hair have colour?

A

melanocytes transfer melanosomes to give hair colour

the melanoctes sit in folicles

66
Q

what are nails

A

dead keratinsed plates covering fingers and toes tip

prtection and dexterity aid

67
Q

where does the nail begin

A

at the groove/root

always growing

68
Q

animal examples of using ketain

A

claws
horns
hooves
antlers

69
Q

what are the three types of sweat glands

A

eccrine
apocrine
sebaceous

70
Q

what is an eccrine gland

A

simple tubular structure in the dermis
sits between hair folicles
secretes watery substances to cool skin down

71
Q

what is an apopcrine gland

A

opens into hair folciles restriced to armpits and groin
special type of sweat
hormonal

72
Q

what is a sebaceous gland

A

everywere except soles and palms
secrete sebum an oily substances
not active till puberty
prevents water evaporation

73
Q

what is an epidermal stem cell

A

involved i everyday regeneration of epidermal layeres

74
Q

what stem cells are found in hair folicles

A

multipotetnt stem cells that under normal conditions stuply the cells for renewal of hair folicles

75
Q

hat is a melanocyte stem ell

A

melanoctes in the hair folicle die during the catagen stage

stem cell population are therefore needed to renew this

76
Q

where are stem cell population in skin found?

A

opposed to be found in the hair bulge

77
Q

what are bulge cells

A

pluripotent cells that can regnerate lots f things

a multipotent pool for regeneration of whole parts of the skin

78
Q

in the short term how does the skin heal wounds

A

platlets are activated
fibrin cots seals the wound off
macrophages and immune cells invade to defend against microbes and clear up debris

79
Q

on the long term how are wounds in skin dealt with

A

fibrobasts invade producing collagen and fibre matrix fr skin to form on and rapir
cell the proliferate creating granuar tissue which is dense

80
Q

in late stages of long term wound healing what happens

A

more fibroblasts secrete more matrix proteins
end result is a functional tissue
may not look the same but acts the same

81
Q

why do scars sometimes appear lighter than before?

A

deep cuts may damage hair folicles and the melanocyte stem cell pool
so the region grows back lighter than before

82
Q

what causes sunburn

A

excessive exposure to UV radiaton

83
Q

what can excessive UV radiation cause

A

DNA damage

speicifically thaimine-thiamine dimers

84
Q

in response to UV radiation what happens

A

inflammatory mediators are released
causes charactisc redness, swelling and pain
body respnds by activating more melanin to protect the skin

85
Q

where on the body is the dermis thickest

A

back

86
Q

whre in the body is the hypodermis thickest

A

around organs on the abdomen

Human physiology (21 decks)

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