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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
what is the stratum basale
stem cell layer at the bottom of the epidermis differentiated keratinocytes come from here
26
what is the stratum spinosum
keratinocytes begin to throw out spindles and differetiate 2-4 cells thick langerhans found here
27
what is the stratum granulosum
granular tissues where cells rapidly accumulate keratin cells begin to flatten and become thin final layer of living cells
28
what is the stratum lucidum
transparent layer only found in thick skins such as palms and feed transitional layer to dead cells
29
what is the stratum corneum
top layer dead keratinocytes layer is thick production and shedding rates are matched
30
features of thick skin?
palms and feed | stratum lucidum layer found here
31
what is the skin like in terms of microbes?
sterile at birth | then colonisation occurs and bacteria from the environment form a flora
32
what type of bacteria are found on the skin
gram positive staphylococcus epidermis is common no net impact largely though
33
what is the dermis?
papillary and retiular layers bulk of skin made of tough connective collgen
34
what is the reticular layer?
thicker layer, secondary strength and resiliance bundles of collagen found here gives support
35
what is the papilary dermis?
thin layer adjacent to apidermis | dermal paillae create ridges
36
what creates fingerprints?
microscopic structures called dermal papillae | they are ridges and projections into the epidermis
37
where are hair and sweat glands found?
papillary dermis
38
where is the major blood supplies for the skin
one in between papillar and reticular, nourished the epidermis one between dermis and hypodermis
39
what cells are there within the dermis
collagen fibroblasts dendrocytes immune cell
40
role of a fibroblast in th dermis?
healing collagen making large ER to support the making of collagen
41
what is a dermal dendrocyte
presents antigens and contibutes to healing
42
what immune cells are found in the dermis
macrophages T cells mast cells
43
what can the dermis sense using neurones?
touch pressure pain hot/cold
44
three types of neuron cells within the dermis?
pacinian corpuscles meissner corpulscles Ruffini curpulscles
45
what is a pacinian corpuscle
pressure sensitive recprot long pressure slow adaptive
46
what is a meissner corpuscles
touch receptors | fast adapting
47
what is a ruffini corpuscle
hot and cold receptor | slow adapting
48
what other receptors are in the dermis?
thermoreceptors pain nocicepors proprioceptors
49
how d ain nociceptors work
fire when noxious stimuli is detected eg. excessive heat or cold excessive mechanical pressure chemicals
50
how do proprioceptors work
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
what does the hypodermis contain?
adipocytes fat cells connective tissue
52
what cells are in the hypodermis
adipose tissue with fat droplets macrophages fibroblasts basement mebrane
53
what is a blister
water leaks out and is protruded into the dermis
54
three component units of hair folicles
folicle going into dermis sebaceous gland papillary
55
three phases of hair growth
anagen catagen telogen
56
what is anagen
growth phase of hair
57
what happens during anagen
stems cells actively divide, hair is extended out from the folicle base
58
what makes hairs shorter than others eg hair air
shorter anagen stage
59
what is catagen
atrophy stage in hair growth
60
what happens during catagen
hair detaches from stem cell papillary layer | no longer grows, no more cells fed int it
61
what is telogen
resting phase in hair growth
62
what happens durin telogen
no new cells hair fals out new process happens again in cycle
63
what causes hair shedding in mamals
hormones trigger atrophy and subsequent resting leading to lots of shedding of hair
64
why is some hair red
unable to make eumelanin
65
how des hair have colour?
melanocytes transfer melanosomes to give hair colour | the melanoctes sit in folicles
66
what are nails
dead keratinsed plates covering fingers and toes tip | prtection and dexterity aid
67
where does the nail begin
at the groove/root | always growing
68
animal examples of using ketain
claws horns hooves antlers
69
what are the three types of sweat glands
eccrine apocrine sebaceous
70
what is an eccrine gland
simple tubular structure in the dermis sits between hair folicles secretes watery substances to cool skin down
71
what is an apopcrine gland
opens into hair folciles restriced to armpits and groin special type of sweat hormonal
72
what is a sebaceous gland
everywere except soles and palms secrete sebum an oily substances not active till puberty prevents water evaporation
73
what is an epidermal stem cell
involved i everyday regeneration of epidermal layeres
74
what stem cells are found in hair folicles
multipotetnt stem cells that under normal conditions stuply the cells for renewal of hair folicles
75
hat is a melanocyte stem ell
melanoctes in the hair folicle die during the catagen stage | stem cell population are therefore needed to renew this
76
where are stem cell population in skin found?
opposed to be found in the hair bulge
77
what are bulge cells
pluripotent cells that can regnerate lots f things | a multipotent pool for regeneration of whole parts of the skin
78
in the short term how does the skin heal wounds
platlets are activated fibrin cots seals the wound off macrophages and immune cells invade to defend against microbes and clear up debris
79
on the long term how are wounds in skin dealt with
fibrobasts invade producing collagen and fibre matrix fr skin to form on and rapir cell the proliferate creating granuar tissue which is dense
80
in late stages of long term wound healing what happens
more fibroblasts secrete more matrix proteins end result is a functional tissue may not look the same but acts the same
81
why do scars sometimes appear lighter than before?
deep cuts may damage hair folicles and the melanocyte stem cell pool so the region grows back lighter than before
82
what causes sunburn
excessive exposure to UV radiaton
83
what can excessive UV radiation cause
DNA damage | speicifically thaimine-thiamine dimers
84
in response to UV radiation what happens
inflammatory mediators are released causes charactisc redness, swelling and pain body respnds by activating more melanin to protect the skin
85
where on the body is the dermis thickest
back
86
whre in the body is the hypodermis thickest
around organs on the abdomen

Human physiology (21 decks)

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