Effect of Environment on Skin Flashcards
What is the term ‘integument’ referring to?
Skin, hair and nails
In which part of the skin are appendages not found?
epidermis
What is the passage of the stem cells produced in the stratum basale?
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.
Describe the anatomy of the nail
Made of keratinocytes, full of keratin
What can cause death to occur following extensive skin damage?
- dehydration and shock
- infection
- heat loss -> hypothermia (sometimes hyperthermia)
- others; protein loss, electrolye imbalance, high-output cardiac failure, renal failure
What is toxic epidermal necrolysis?
A rare adverse drug reaction causing detatchment of epidermis -> often fatal!
What are some environmental ‘insults’ to the skin? (5)
- irradiation + UV light
- Physical trauma (burns, friction, pressure)
- irritants
- allergens
- microbes, ectoparasites
What prevents our skin from drying out?
Waterproof epidermis and oil from sebaceous glands
What features of our skin protect us from friction and impact?
- thick, regenerating epidermis; keratin
- nails
- basement membrane anchoring epidermis to dermis, wavy border against shear forces
- collagen fibres in dermis
What is hyperkeratosis and lichenification?
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.
What is the importance of melanin?
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)
How do melanocytes function within the basal layer?
Have branches/dendrites that feed pigment to surrounding keratinocytes, they transfer melanosomes to basal keratinocytes (same layer) and few go to upper layers*
What is polymorphic light eruption?
One of several types of allergy to the sun, not harmful but itchy and embarrassing
What is solar elastosis?
Often due to excessive sun exposure, resulting in loss of elasticity and wrinkly appearance
What are naevi?
Moles - benign proliferation of melanocytes, many or large naevi pose a risk factor for melanoma skin cancer!
What are ephelides?
Freckles - genetic component involved, linked to red/fair hair, abundant in sun-exposed areas
What are solar lentigos?
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.
What are solar keratoses?
Dysplastic growth of keratinocytes - rough, scaly patches on sun-exposed areas such as the head and face
What are the main types/divisions of skin cancer?
Melanoma (melanocytes) or non-melanoma (keratinocytes)
Non-melanomas can be divided into squamous cell carcinoma and basal cell carcinoma
What is an important feature of melanomas?
Can be thin, but dangerous - rapid spread, can be caused by UVA and UVB
What is an advantage of UV?
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)
What is ultraviolet radiotherapy used for (conditions)?
Vitiligo, psoriasis
What are the different types of thermal burn?
- 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
What is irritant contact dermatitis?
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
What is allergic contact dermatitis?
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)
What is paronychia?
Infection of the nail fold, can be fungal or bacterial
What is tinea capitis?
Ringworm of the scalp, children susceptible, get ring-shaped rashes - FUNGUS
What is impetigo?
Children can get impetigo, infectious, spreads rapidly - bacterial. Should be contained immediately.
