Basic Skin Biology Flashcards
What are the 6 functions of the skin?
- Protective barrier against environmental insults.
- Temperature regulation.
- Sensation.
- Vitamin D synthesis.
- Immunosurvelliance.
- Cosmesis.
What complications can lead to erythroderma?
- Hypothermia: loss of thermoregulation.
- Infection: loss of protective barrier.
- Renal failure: insensible losses.
- High output cardiac failure (dilated skin vessels).
- Protein malnutrition (high turn over of skin).
What is erythroderma?
Where 90%+ of the body surface are effected by erythematous and exfoliative.
What are the causes of erythroderma?
- Psoriasis.
- Eczema.
- Drugs.
- Cutaneous T cell lymphoma.
What are the symptoms of erythroderma?
- Pruritus.
- Fatigue.
- Anorexia.
- Feeling cold.
What are the signs of erythroderma?
- Erythematous.
- Thickened.
- Inflamed.
- Scaly.
- No sparing.
Identify and describe the 4 major cell types of the epidermis.
- Keratinocytes: protective barrier..
- Langerhans cells: antigen presenting cells.
- Melanocytes: produce melanin (pigment to the skin and protect cell nuclei from UV DNA damage).
- Merkel Cells: contain specialised nerve endings for sensations.
Identify the 4 layers of the epidermis.
- Stratum corneum (horny).
- Granular layer.
- Prickle layer.
- Basal layer.
Stratum lucidum: found in areas of thicker skin like palms and soles.
What 3 things changing can cause pathology of epidermis?
- Epidermal Turnover.
- Surface.
- Pigmentation.
What is the dermis composed of?
Collagen, elastin and glycosaminoglycans, immune cells, nerve cells, skin appendages, lymphatics and blood vessels.
What are the main functions of the dermis?
Strength and elasticity.
What is a sebaceous gland?
A gland that produces sebum through hair follicles (pilosebaceous unit). Sebum lubricates the skin.
What is sebum?
A lubricant of the skin, stimulated by the conversion of androgen to dihydrotesterone, active after puberty.
Increased sebum production and bacterial colonisation is associated with acne vulagris.
What are eccrine and apocrine glands?
Involved in the regulation of body temperature. Innervated by sympathetic. Eccrine are widespread and apocrine are active following puberty and are found in axillae, areolae, genitalia and the anus.
Describe the structure of hair.
Hair consists of modified keratin, divided into hair shaft and hair bulb.
What are the 3 main types of hair?
- Lanugo hair.
- Vellum hair: short hair all over body.
- Terminal hair: coarse long hair.
What are the 3 phases of a hair follicle growth cycle?
- Anagen.
- Catagen.
- Telogen.
Describe the structure of nails.
Consists of a nail plate which arises from the nail matrix at the posterior nail fold and rests on the nail bed.
Nail bed contains blood capillaries.
Describe the rash in atopy eczema.
Generalised, symmetrical rash consisting of erythematous, scaly, ill-defined, patchy erosions.
What complications can arise from atopic eczema?
Heavy bacterial colonisation,
Eczema herpeticum,
Superimposed contact allergy,
Reduced QoL.
How can atopic eczema be treated?
Avoidance of exacerbating factors, generous use of non-perfumed emollient, topical steroids, phototherapy and systemic therapies.
How can you describe urticaria?
Generalised, symmetrical rash consisting of well defined erythematous urticated papules and plaques (wheals).
What is urticaria?
Mast cell degranulation and histamine release leading to increased capillary permeability and leakage of fluid into surrounding tissue.
Transient (<24hrs)+/- angioedema.
How is urticaria treated?
Eliminate the underlying cause. Give high dose anti-histamines and an acute course of oral steroids.
How does someones tinea (fungal) infection rash look like?
Body-solitary, well-defined, erythema, scaly, annular (with central clearing) plaque. Scalp-localised, solitary, erythema, scale with accompanying hair loss.
What does molluscum contagiosum rashes look like?
Localised, unilateral skin condition consisting of multiple well defined, skinny, dome-shaped umbilicated papule.
What is molluscum contagiosum?
A pox virus infection with a 2-6 week incubation period. More common in atopic and immuno-compromised patients. Most self resolve within 6-9months and thus no treatment is required.
How does drug exanthem look?
Generalised, macular, popular, erythematous rash.
Describe drug exanthem.
Appear after a latent period required for induction.
Cell mediated immune reaction.
Most common reaction is macular-papular rash.
How does shingles rash look?
Localised dermatomal rash consisting of papule, vesicule, bulla, erosion with crusts.
Describe shingles.
Herpes zoster infection.
Dermatomal.
Attack usually result of re-activation of virus which has remained dormant in sensory root ganglion since an earlier episode of chicken pox.
Elderly and immuno-compromised at higher risk.
Associated with burning pain.
Lasts 2-3 weeks.
What are the complications of shingles?
Secondary bacterial infection, paralysis (motor nerve involvement can occur), corneal ulcers and scarring (if ophthalmic division of trigeminal nerve involved), neuralgic pain.
How should shingles be treated?
Systemic aciclovir within 2 days of episode and analgesics.
