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Physiology 2 : skin > Effects of the environments on the skin > Flashcards

Effects of the environments on the skin Flashcards

1
Q

Thermoregulation

A

Regulation of body temperature

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2
Q

Waveband

A

A band of wavelengths (of radiation)

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3
Q

Ultraviolet (A, B, and C)

A

the three wavebands of UV light. Band UVA comprises the longest and UVC the shortest wavelengths. All shorter than visible light.

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4
Q

Solar elastosis

A

loss of skin elasticity (wrinkles)

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5
Q

Naevus (pl. naevi)

A

a skin mole

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6
Q

Melanoma

A

cancer of melanocytes

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7
Q

Non-melanoma skin cancer

A

as it sounds, but nearly always from keratinocytes

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8
Q

Dermatitis

A

Skin inflammation

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9
Q

Allergen

A

Something that can cause an allergy

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10
Q

Papilloma

A

A wart

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11
Q

The integument

A

Interface between body and environment. Thus subject to a wide range of insults (stresses).

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12
Q

The skin is a vital organ

A

On extensive epidermal (or epidermal + dermal) damage, e.g. with severe burns or a rare drug reaction, death may occur, owing to one or more of:
• Dehydration and shock
• Infection
• Heat loss and hypothermia (or sometimes hyperthermia due to impaired thermoregulation).
• Others: protein loss, electrolyte imbalance, high-output cardiac failure, renal failure.

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13
Q

Toxic epidermal necrolysis

A

(rare adverse drug reaction)

Detachment of epidermis. Often fatal

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14
Q

Environmental insults

A
  • Microbes, ectoparasites
  • Allergens
  • Irritants
  • Physical trauma (burns, friction, pressure etc)
  • Irradiation & UV light
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15
Q

How do environmental insults affect the body?

A
  • Homeostasis

- thermoreg. etc

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16
Q

Drying of the skin

A

Waterproof epidermis + oil from sebaceous glands

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17
Q

Friction, impact

A

o Thick, regenerating epidermis; keratin
o Nails
o Basement membrane anchoring epidermis to dermis, wavy border against shear forces
o Collagen fibres in dermis (strong, running in all directions)

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18
Q

Heat

A

Sweating; vasodilatation

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19
Q

Cold

A

Subcutaneous fat, adaptable blood supply, hair (head)

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20
Q

Burns, injury

A

Thick, regenerating epidermis

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21
Q

Radition/ sunlight

A

Thick epidermis; melanin

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22
Q

Infection

A

Impervious epidermis; resident cells of immune system

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23
Q

Sweating & vasodilation

A

Due to heat

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24
Q

Hyperkeratosis

A

Thickening of stratum corneum with rubbing or pressure (e.g. feet, guitarist fingers), or (slightly) after ultraviolet exposure. Slow (weeks).

25
Q

Tanning

A

(melanocyte response) after ultraviolet exposure. Quite slow (days).

26
Q

Vasoconstriction

A

Fast due to the cold

27
Q

Thermoregulation by blood supply

A

Arteriovenous (AV) shunts are anastomoses between arterioles and venules. Numerous in dermis.
Respond to thermoreceptors in skin – hot/cold.

Shunts open or close respectively to decrease or increase blood flow to the superficial vascular plexus in the papillary dermis (just below epidermis). Hence skin goes redder (more heat loss) or bluer.

28
Q

Emotions and the skin

A

Thermoregulation can also be a response to emotion/ sympathetic nervous system

29
Q

UV protection: epidermal melanin

A

The colour of human skin is due mainly to melanin (dark skin) and haemoglobin (light skin)
Much normal genetic variation in the amount of melanin (>12 genes known)
Melanin protects against DNA damage and thus skin cancer, especially in dark (black & Asiatic) skin: incidence only 8-10% that of white people

30
Q

UV protection: tanning

A

Melanocytes increase activity - make & transmit more melanin.
Gives some protection against UV.
Additional protection by skin thickening in response to UV.

31
Q

MSH

A

Melanocyte-stimulating hormone

32
Q

MC1R

A

Melanocortin 1 receptor

33
Q

What does UV do?

A

Damages DNA in the basal keratinocyte which signals the release of MSH.
MSH then binds to MC1R and triggers the transcription of melanin.
Cell division increases ad this results in an increase of melanin in the basal keratinocyte

34
Q

Tyrosine to pheomelanin or eumelanins

A 
Tyrosine -> L-DOPA (by TYR) 
L-DOPA -> DOPAquinone 
DOPAquinone can undergo 2 process
TRPs then creates eumelanins (brown to black 
OR 
TRPS create pheomelanins 
(yellow to red)
35
Q

L-DOPA

A

L-3,4-dihydroxyphenylalanine

36
Q

TRPs

A

Tyrosinase-related proteins

37
Q

TYR

A

Tyrosinase

38
Q

Protection against microorganisms

A

Langerhans cells
(& rest of immune system)
Small cells in non-basal layers of skin. Dendritic cells.
Function: Antigen-presenting cells (like macrophages). Form a network in the epidermis – part of immune system.

39
Q

Abnormal effects of the environment

A
  • Friction/ scratching
  • Ultraviolet irradiation
  • Burns
  • Irritants
  • Allergens
  • Microbes (bacteria, viruses, fungi)
40
Q

Lichenification

A

Friction/scratching
More extreme form of hyperkeratosis.
Reaction to excessive rubbing or scratching/skin conditions.

41
Q

UVA

A

Longest UV wavlength

42
Q

Sunburn

A
  • Is a radiation burn
  • Blisters, inflammation and cell death (severe DNA damage)
  • “Ever sunburnt” associates with increased risk of skin cancer
  • So does “ever used a UV sunbed below age 35” – by 75%
43
Q

Naevi (moles)

A

(Singular, naevus. USA: nevus)
Benign proliferation of melanocytes
Many or large naevi: risk factor for melanoma skin cancer

44
Q

Freckles (ephelides)

A

Involve a genetic component. Also linked to red/fair hair. Often MC1R gene variants.
Sun-exposed areas

45
Q

Solar lentigos [liver spots, age spots]

A

Age related

46
Q

Solar keratoses

A

Dysplastic growth of keratinocytes

47
Q

Basal cell carcinoma [‘rodent ulcer’]

A

Often curable by surgery - especially if reported early!

48
Q

Skin cancer

A

Melanoma (melanocytes) - most dangerous
Non-melanoma (mostly keratinocytes) - most common -
Squamous cell carcinoma or Basal cell carcinoma (COMMONEST)

49
Q

Melanoma

A

Can be thin, but still dangerous – rapid spread

50
Q

UV benefits

A

UV needed for vitamin D3 production in skin.
15-min summer sun on face & arms per day enough for white skin, longer for dark skin. Or take tablets.
Ultraviolet radiotherapy for skin conditions, e.g. vitiligo, psoriasis

51
Q

Irritant contact dermatitis

A

Occurs when too much exposure to a substance.
Can still use it, but reduce the amount.
People vary insensitivity
Any of Redness, itching, swelling, blistering and/or scaling

52
Q

Allergen contact dermatitis

A

Allergy to something that contacts skin - immune system involved.
Tiny amount may be sufficient.
Varies greatly between people. May develop after long or short use.
Any of: Redness, itching, swelling, blistering and/or weeping.
Avoid allergen in future

53
Q

Latex is a

A

allergen

54
Q

Paronychia

A

(nail fold infection-fungal or bacterial)

55
Q

Fungal

A

Tinea capitis (scalp ringworm)

56
Q

Bacterial

A

Impetigo

Cellulitis (streptoccus)

57
Q

Virus (viral human papilloma virus)

A

HPV - Warts

58
Q

Infection

A

Portal of entry: microbes can enter breach in epidermis
(e.g. Streptococcus in cellulitis)
Impaired immunity predisposes to infection,
e.g. HIV and viral warts;
eczema herpeticum, which is herpes (cold sore) virus infecting eczema

Physiology 2 : skin (2 decks)

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