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my phase 1 > Skin > Flashcards

Skin Flashcards

1
Q

what are the functions of skin

A
  • physical barrier
  • immunological barrier
  • thermoregulation
  • vitamin D synthesis
  • UV protection
  • sensory organ
  • regulation of H2O loss - waterproof barrier
  • endocrine organ
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2
Q

3 main layers of the skin

A
  1. Epidermis
  2. Demis
  3. Subcutis / Hypodermis
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3
Q

what features of the skin make it waterproof

A
  • Tight junctions between cells in the stratum granulosum
  • keratin in the stratum corneum
  • epidermal lipid barrier
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4
Q

where does vitamin D synthesis take place

A

in the epidermis and dermis

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5
Q

where is vitamin D stored

A

in the subcutis adipocytes as it is fat solube

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6
Q

name the layers of the epidermis

A
  1. stratum corneum [superficial]
  2. stratum lucidum
  3. stratum granulosum
  4. stratum spinosum
  5. stratum basale [deep]

Come Lets Get Sun Burnt

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7
Q

what lies within the dermis

A

glands

connective tissue

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8
Q

what lies within the subcutis

A

fat

connective tissue

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9
Q

does the epidermis contain collagen

if so what type

A

yes

type 4 collagen

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10
Q

Where does proliferation of the skin occur?

A

stratum basale only

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11
Q

summarise vitamin D synthesis

A
  1. 7-dehydrocholesterol in skin → Cholecalciferol via UV radiation
  2. cholecalciferol transported to teh liver and in the diet → 25-hydroxyvitamin D
  3. 25-hydroxyvitamin D in the kidneys → Calcitriol [1,25-dihydroxyvitamin D3] vi 1-alpha hydrolase
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12
Q

which hormones can have an effect on the skin

A

thyroid hormones

androgens

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13
Q

how do androgens affect the skin

A

they act on follicles and sebaceous glands

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14
Q

how do thyroid hormones affect the skin

A

they act on

  • kerantinocytes
  • follicles
  • sebaceous glands
  • eccrine glands
  • dermal fibroblasts
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15
Q

what hormones are produced in the skin

A
  • vitamin D3 - cholecalciferol
  • IGF - insulin-like growth factor
  • DHT -5α-dihydrotestosterone
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16
Q

what is skin colour dependent on

A

melanin production NOT number of melanocytes

Carotenoids - orange pigment

Oxy/deoxyhaemoglobin

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17
Q

what are langerhans cells

A

macrophages of the skin

18
Q

what are the effects of UV-A and UV-B on the skin

A
  • burns
  • suppressed action of Langerhans cells
  • photo-aging
  • DNA-damage → cancers
19
Q

what is melanin made

where is it produced?

A
  • made from tyrosine
  • synthesised in melanosomes within melanocytes in the basal layer
20
Q

where is most melanin found

A
  • Most melanin lies within keratinocytes not melanocytes
  • dendritic cells transfer melanin from melanocytes to keratinocytes
21
Q

types of melanin

A
  • Pheomelanin (red/yellow)
  • Eumelanin (brown/black)
22
Q

how is melanin photoprotective

A

it scatters and filters UV light

23
Q

what immune cells can be found in thte skin and where

A
  • dermis
    • Langerhans cells
  • Epidermis
    • NKC
    • T cells
    • Mast cells
    • Dendritic cells
    • Macrophages
24
Q

what happens when a Langerhan cells is challenged

A
  1. the LC migrates from epidermis → dermis and lymph nodes to activate a T-cell response
  2. keratinocytes proliferate to increase cytokine secretion
  3. leukocytes enter the skin from blood
25
Q

how does the skin detect touch

A
  • via encapsulated mechanoreceptors in the dermis:
    • meissner corpuscles - touch
    • pacinian corpuscles -pressure and vibration
  • Merkle cells located on the stratum basal for light touch
  • Myelinated and un-myelinated sensory nerve endings in dermis for Pain, Itch, Temperature
26
Q

what’s this

what’s its function

A

Pacinian corpuscle

pressure and vibration

27
Q

what’s this

what’s its function

A

Meissner Corpuscles

fine touch

28
Q

how does skin regulate body temperature

A
  • insulation via subcutaneous fat
  • heat loss via:
    • cutaneous blood flow
    • eccrine sweating
29
Q

describe how cutaneous blood flow regulates body temp

A
  • there is a deep and superficial plexus of blood in the upper and lower reticular dermis
  • loops of blood vessels extend between each plexus
  • blood is shunted from deep to superficial to lose heat and vice versa to conserve.
  • this is regulated by the sympathetic system:
    • sympathetic alpha-noradrenergic → vasoconstriction
    • sympathetic cholinergic nerves → vasodilation
30
Q

which sweat gland is more common

A

eccrine are more common than apocrine as they are found everywhere in the dermis of the skin

apocrine glands are only found in the ear, axilla and groin

30
Q

which sweat gland is more common

A

eccrine are more common than apocrine as they are found everywhere in the dermis of the skin

apocrine glands are only found in the ear, axilla and groin

31
Q

functions of subcutaneous fat

A

shock absorption

insulation

energy storage

32
Q

in what layer of skin is keratin formed

A

stratum granulosum

33
Q

what is the largest layer of the epidermis

A

stratum spinosum

34
Q

how can you locate the epidermis-dermis junction

A

the ridged interdigitating pegs that help anchor them together = dermal papillae

35
Q
A
36
Q

describe the brick wall analogy for the skin

A

skin cells = brick

lipid lamellae = the cement

corneodesmosomes = the steel rods that joins the cells together – the adhesion molecules that keep the corneocytes together

37
Q

what is the skin barrier composed of

A
  • lipid lamellae - forms a water barrier that allows the cell to swell
  • natural moisturising factor [NMF]- maintains pH
  • corneocytes - cells filled with NMF
  • corneodesmosomes - link corneocytes
  • cornified envelope
38
Q

what is the pH of healthy skin

A

5.5

39
Q

what factors maintain a healthy skin barrier

A
  1. profilaggrin → filaggrin → NMF.
    • this helps to maintain hydration within the skin by keeping H2O in the corneocytes
    • it also maintains a slightly acidic environment at the outer surface of the stratum corneum.
      • a high pH → protease inhibitor not working
  2. balance in the introduction of new cells from the basal layer and removal of old cells
    • desquamation is achieved by protease enzymes breaking down the extracellular corneodesmosomes
  3. lipid lamella acts like a barrier:
    • keeps H2O inside the cell.
    • irritants and allergens bounce off the skin
40
Q

what is the impact of not having progfilaggrin

A
  • no profilaggrin → no filaggrin → lack of NMF →
    • less H2O retention in corneocytes
    • a higher pH - meaning protease inhibitors don’t work
    • damaged corneodesmosomes due to higher pH
    • breakdown of skin barrier → increased risk of infection

my phase 1 (11 decks)

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