Effect of Environment on Skin

Question 1

What is the term ‘integument’ referring to?

Answer 1

Skin, hair and nails

Question 2

In which part of the skin are appendages not found?

Answer 2

epidermis

Question 3

What is the passage of the stem cells produced in the stratum basale?

Answer 3

Daughter cells move distally through epidermis, differentiate into mature keratinocytes, make lots of tough/waterproof keratin.

At stratum corneum, cornified keratinocytes lose nuclei, contuinuing to move distally.

Question 4

Describe the anatomy of the nail

Answer 4

Made of keratinocytes, full of keratin

Question 5

What can cause death to occur following extensive skin damage?

Answer 5

• dehydration and shock
• infection
• heat loss -> hypothermia (sometimes hyperthermia)
• others; protein loss, electrolye imbalance, high-output cardiac failure, renal failure

Question 6

What is toxic epidermal necrolysis?

Answer 6

A rare adverse drug reaction causing detatchment of epidermis -> often fatal!

Question 7

What are some environmental ‘insults’ to the skin? (5)

Answer 7

• irradiation + UV light
• Physical trauma (burns, friction, pressure)
• irritants
• allergens
• microbes, ectoparasites

Question 8

What prevents our skin from drying out?

Answer 8

Waterproof epidermis and oil from sebaceous glands

Question 9

What features of our skin protect us from friction and impact?

Answer 9

• thick, regenerating epidermis; keratin
• nails
• basement membrane anchoring epidermis to dermis, wavy border against shear forces
• collagen fibres in dermis

Question 10

What is hyperkeratosis and lichenification?

Answer 10

Hyperkeratosis is the thickening of the stratum corneum layer with rubbing or pressure (eg. feet, guitarist fingers) or after UV exposure.

Lichenificaiton is a more extreme form of hyperkeratosis, reaction to excessive rubbing or scratching/skin conditions.

Question 11

What is the importance of melanin?

Answer 11

Gives colour to human skin (dark), there’s much genetic variation in the amount of melanin.

Protects against DNA damage and thus skin cancer, especially in dark skin (advantage)

Question 12

How do melanocytes function within the basal layer?

Answer 12

Have branches/dendrites that feed pigment to surrounding keratinocytes, they transfer melanosomes to basal keratinocytes (same layer) and few go to upper layers*

Question 13

What is polymorphic light eruption?

Answer 13

One of several types of allergy to the sun, not harmful but itchy and embarrassing

Question 14

What is solar elastosis?

Answer 14

Often due to excessive sun exposure, resulting in loss of elasticity and wrinkly appearance

Question 15

What are naevi?

Answer 15

Moles - benign proliferation of melanocytes, many or large naevi pose a risk factor for melanoma skin cancer!

Question 16

What are ephelides?

Answer 16

Freckles - genetic component involved, linked to red/fair hair, abundant in sun-exposed areas

Question 17

What are solar lentigos?

Answer 17

Harmless patch of darkened skin. It results from exposure to ultraviolet (UV) radiation, which causes local proliferation of melanocytes and accumulation of melanin within the skin cells. Age-related.

Question 18

What are solar keratoses?

Answer 18

Dysplastic growth of keratinocytes - rough, scaly patches on sun-exposed areas such as the head and face

Question 19

What are the main types/divisions of skin cancer?

Answer 19

Melanoma (melanocytes) or non-melanoma (keratinocytes)

Non-melanomas can be divided into squamous cell carcinoma and basal cell carcinoma

Question 20

What is an important feature of melanomas?

Answer 20

Can be thin, but dangerous - rapid spread, can be caused by UVA and UVB

Question 21

What is an advantage of UV?

Answer 21

Needed for vitamin D production in the skin (15 min summer sun on face and arms per day for white skin, longer for dark skin)

Question 22

What is ultraviolet radiotherapy used for (conditions)?

Answer 22

Vitiligo, psoriasis

Question 23

What are the different types of thermal burn?

Answer 23

• Superficial burn - epidermis destroyed (mild)
• Sebaceous glands - may not scar

Both of these are partial thickness

• Deep burn - full thickness when most of dermis is damaged, loss of pinprick sensation - will scar

Question 24

What is irritant contact dermatitis?

Answer 24

Occurs when too much exposure to a substance, can still use it but need to reduce amount. People vary in sensitivty.

Symtoms: redness, itching, swelling, blistering and/or scaling

Very COMMON - eg in solvents, industry, cleaning

Question 25

What is allergic contact dermatitis?

Answer 25

It’s an allergy to something that contacts skin - immune response. Tiny amount may be sufficient.

Varies greatly between people, may develop after long or short use.

Symptoms: Redness, itching, swelling, blistering and/or weeping

Relatively uncommon (metals, jewellery, latex, nickel)

Question 26

What is paronychia?

Answer 26

Infection of the nail fold, can be fungal or bacterial

Question 27

What is tinea capitis?

Answer 27

Ringworm of the scalp, children susceptible, get ring-shaped rashes - FUNGUS

Question 28

What is impetigo?

Answer 28

Children can get impetigo, infectious, spreads rapidly - bacterial. Should be contained immediately.