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SGUL - Physiology 2 > Skin - Effect Of Environment On Skin > Flashcards

Skin - Effect Of Environment On Skin Flashcards

1
Q

Give reasons to why the skin is important

A
  • The skin is a vital organ
  • Normal adaptations of the skin to environmental pressures
  • Abnormal effects of the environment such as:
  • Physical damage to skin, nails and hair
  • Ultraviolet damage: Burns, ageing and skin lesions
  • Irritants, allergies and dermatitis
  • Cutaneous infections
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2
Q

What is the integument?

A
  • The interface between the body and the environment
  • Thus subject to a wide range of insults
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3
Q

What May happen to the skin with extensive epidermal damage with severe burns? (Environmental insults on the skin)

A

Death May occur owing to one or more of
- Dehydration and shock
- Infection
- Heat loss and hypothermia
- Other factors such as protein loss, renal failure, electrolyte imbalance

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4
Q

State one type of fatal skin disease

A
  • Toxic epidermal necrolysis: a rare adverse drug reaction
  • Detachment of the epidermis
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5
Q

List the different environmental insults on the skin

A
  • Irradiation & UV light
  • Allergen
  • Irritant
  • Microbes, parasites
  • Physical trauma (Burns, friction, pressure)
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6
Q

List some of the protective features of the skin

A
  • Drying: Waterproof epidermis + oil from sebaceous glands
  • Friction, impact: Thick regenerating epidermis, Nails
  • Heat: Sweating, Vasodilation
  • Cold: Subcutaneous fat, adaptable blood supply, hair
  • Burns, Injury: Thick regenerating epidermis
  • Radiation/sunlight: Thick epidermis, melanin
  • Infections: Impervious epidermis
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7
Q

List some normal skin adaptations

A
  • Sweating & Vasodilation in heat: Vasoconstriction in cold (Quite fast - Minutes)
  • Tanning: Melanocyte response after ultraviolet exposure (Quite slow - Days)
  • Hyperkeratosis: Thickening of stratum Corneum with rubbing or pressure after ultraviolet exposure (Quite slow - Days)
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8
Q

Describe how thermoregulation Is controlled by blood supply

A
  • Arteriovenous (AV) shunts are anastomoses between arteriolars and venules
  • Numerous in dermis
  • Respond to thermoreceptors in the skin: Hot/Cold
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9
Q

When do the shunts open and close during thermoregulation of the blood supply

A
  • Shunts open in response to decrease of blood flow to the superficial vascular plexus min the papillary dermis
  • Shunts close in response to increase of blood flow to the superficial vascular plexus min the papillary dermis
  • In face: Can also respond to emotion/sympathetic nervous system (blushing)
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10
Q

What happens if the arteriovenous shunts are shut off for too long?

A

Danger of damage (Frostbite’s May occur)

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11
Q

What is used to determine the colour of our skin?

A
  • Dark skin is mainly due to melanin
  • Light skin is mainly due to Haemoglobin
  • There is a normal amount of genetic variation in the amount of melanin (<12 genes)
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12
Q

What does Melanin do in the skin?

A
  • Protects against DNA damage and therefore against skin cancers
  • Especially in dark (black & asiatic) skin
  • Incidence is only 8-10% of that of white people
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13
Q

What happens during UV protection?

A
  • The transfer of melanosomes (pigment granules) mainly to basal keratinocytes
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14
Q

What does Melanocytes do in terms of tanning?

A
  • Melanocytes increase activity
  • Make and transmit more Melanin
  • Gives some protection against UV
  • Additional protection by skin thickening in response to UV light
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15
Q

What is the process of suntanning?

A

Tyrosine -> L DOPA (via TYR) -> Dopaquinone (via TYR) -> either Eumelanins (brown to black) or Pheomelanins (yellow to red) via TRP’s
TYR = Tyrosinase TRPs = Tyrosine related proteins

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16
Q

What are langerhans cells?
What is the use of Langerhans cells in the body?

A
  • Small cells in the non basal layer of the skin
  • Protection against Microorganisms
17
Q

What is the function of langerhans cells?

A
  • They’re antigen presenting cells
  • Form a network in the epidermis which is a part of the immune system
18
Q

List some abnormal effects of the environment

A
  • Friction-scratching
  • Ultraviolet irradiation
  • Burns
  • Irritants
  • Allergens
  • Microbes (Bacteria, Viruses and fungi)
19
Q

What is lichenification?

A
  • A more extreme form of hyperkeratosis
  • A Reaction to excessive rubbing or scratching
20
Q

Why is the Ozone layer useful?

A
  • Helps block out UV light from entering the earths atmosphere and damaging the skin
  • Blocks UVC, some UVA and UVB
21
Q

What is sunburn caused by?
How can it be treated?

A
  • Caused by UV irradiation
  • It is a radiation burn
  • Causes Blisters, inflammation and cell death
  • Associates with increased risk of cancer
  • Even if you’ve used a radiation bed below age 35 by 75%
22
Q

What are Naevi? (Moles)

A
  • benign proliferation of melanocytes
  • Many or large naevi are risk factors for melanoma skin cancers
23
Q

What are freckles? (Ephelides)

A
  • Involve a genetic component
  • Linked to either Red or Fair hair
  • Often linked to MC1R gene variants
  • Affects areas exposed to the sun
24
Q

List the different skin related diseases caused by UV radiation

A
  • Sunburn
  • Polymorphic light eruption
  • Wrinkles: Solar elastosis (Loss of elasticity)
  • Naevi (moles)
  • Freckles (ephelides)
  • Solar lentigos [liver spots, age spots]
  • Solar keratoses
  • Basal cell carcinoma
  • Melanoma
25
Q

What is special about a basal cell carcinoma?

A
  • Often curable by surgery
  • especially if reported early!
26
Q

What is a melanoma?

A
  • Caused by UV radiation
  • Can be thin but is still dangerous
  • Spread rapidly
27
Q

What are the benefits of UV light?

A
  • UV is needed for vitamin D3 production in skin
  • 15 minutes of summer sun on face & arms per day is enough for white skin
  • Longer for dark skin or take tablets
  • Ultraviolet radiotherapy for skin conditions
28
Q

What are the different types of skin burns?

A

1st degree burns: Burns up to the epidermis
2nd degree burns: Burns past the epidermis and half way through the dermis (May not scar)
3rd degree burns: Burns through the epidermis, dermis and to the fat in the skin. (Leaves scarring)

29
Q

How do irritants contact dermatitis?

A
  • Occurs when there’s too much exposure to a substance
  • Can still use it, but reduce amount
  • People vary in sensitivity
  • Any of redness, itching, swelling, blistering and/or scaling
30
Q

How do allergens contact dermatitis?

A
  • Allergy to something that contacts skin, immune system involved
  • Tiny amounts 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
31
Q

Comment on how common/uncommon irritants or allergic contact dermatitis’s are

A
  • Irritant contact dermatitis is common
  • Allergic contact dermatitis is relatively uncommon
  • Sensitisation first: Langerhans cells process antigen and present to lymphocytes
  • Delayed hypersensitivity occurs at next exposure (memory T cells)
32
Q

List the different types of microbes

A
  • Paronychia
  • Fungal: Tinea capitis
  • Bacterial impetigo
  • Bacterial cellulitis
  • Virus: Human papilloma virus (HPV)
33
Q

Describe how an infection works

A
  • Portal of entry: Microbes can enter breach in epidermis
  • Impaired immunity predisposes to infection such as:
  • HIV and viral warts
  • Eczema herpeticum, which is herpes (cold sore) virus infecting eczema
34
Q

Conclude the skin as a whole

A

The skin is a vital organ with normal adaptive mechanisms to: temperature changes (sweating, vasodilation & vasoconstriction), friction (hyperkeratosis) and UV radiation (melanin production).

SGUL - Physiology 2 (37 decks)

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