Basic Skin Biology

Question 1

What are the 6 functions of the skin?

Answer 1

1. Protective barrier against environmental insults.
2. Temperature regulation.
3. Sensation.
4. Vitamin D synthesis.
5. Immunosurvelliance.
6. Cosmesis.

Question 2

What complications can lead to erythroderma?

Answer 2

1. Hypothermia: loss of thermoregulation.
2. Infection: loss of protective barrier.
3. Renal failure: insensible losses.
4. High output cardiac failure (dilated skin vessels).
5. Protein malnutrition (high turn over of skin).

Question 3

What is erythroderma?

Answer 3

Where 90%+ of the body surface are effected by erythematous and exfoliative.

Question 4

What are the causes of erythroderma?

Answer 4

1. Psoriasis.
2. Eczema.
3. Drugs.
4. Cutaneous T cell lymphoma.

Question 5

What are the symptoms of erythroderma?

Answer 5

1. Pruritus.
2. Fatigue.
3. Anorexia.
4. Feeling cold.

Question 6

What are the signs of erythroderma?

Answer 6

1. Erythematous.
2. Thickened.
3. Inflamed.
4. Scaly.
5. No sparing.

Question 7

Identify and describe the 4 major cell types of the epidermis.

Answer 7

1. Keratinocytes: protective barrier..
2. Langerhans cells: antigen presenting cells.
3. Melanocytes: produce melanin (pigment to the skin and protect cell nuclei from UV DNA damage).
4. Merkel Cells: contain specialised nerve endings for sensations.

Question 8

Identify the 4 layers of the epidermis.

Answer 8

1. Stratum corneum (horny).
2. Granular layer.
3. Prickle layer.
4. Basal layer.
   Stratum lucidum: found in areas of thicker skin like palms and soles.

Question 9

What 3 things changing can cause pathology of epidermis?

Answer 9

1. Epidermal Turnover.
2. Surface.
3. Pigmentation.

Question 10

What is the dermis composed of?

Answer 10

Collagen, elastin and glycosaminoglycans, immune cells, nerve cells, skin appendages, lymphatics and blood vessels.

Question 11

What are the main functions of the dermis?

Answer 11

Strength and elasticity.

Question 12

What is a sebaceous gland?

Answer 12

A gland that produces sebum through hair follicles (pilosebaceous unit). Sebum lubricates the skin.

Question 13

What is sebum?

Answer 13

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.

Question 14

What are eccrine and apocrine glands?

Answer 14

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.

Question 15

Describe the structure of hair.

Answer 15

Hair consists of modified keratin, divided into hair shaft and hair bulb.

Question 16

What are the 3 main types of hair?

Answer 16

1. Lanugo hair.
2. Vellum hair: short hair all over body.
3. Terminal hair: coarse long hair.

Question 17

What are the 3 phases of a hair follicle growth cycle?

Answer 17

1. Anagen.
2. Catagen.
3. Telogen.

Question 18

Describe the structure of nails.

Answer 18

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.

Question 19

Describe the rash in atopy eczema.

Answer 19

Generalised, symmetrical rash consisting of erythematous, scaly, ill-defined, patchy erosions.

Question 20

What complications can arise from atopic eczema?

Answer 20

Heavy bacterial colonisation,
Eczema herpeticum,
Superimposed contact allergy,
Reduced QoL.

Question 21

How can atopic eczema be treated?

Answer 21

Avoidance of exacerbating factors, generous use of non-perfumed emollient, topical steroids, phototherapy and systemic therapies.

Question 22

How can you describe urticaria?

Answer 22

Generalised, symmetrical rash consisting of well defined erythematous urticated papules and plaques (wheals).

Question 23

What is urticaria?

Answer 23

Mast cell degranulation and histamine release leading to increased capillary permeability and leakage of fluid into surrounding tissue.
Transient (<24hrs)+/- angioedema.

Question 24

How is urticaria treated?

Answer 24

Eliminate the underlying cause. Give high dose anti-histamines and an acute course of oral steroids.

Question 25

How does someones tinea (fungal) infection rash look like?

Answer 25

Body-solitary, well-defined, erythema, scaly, annular (with central clearing) plaque. Scalp-localised, solitary, erythema, scale with accompanying hair loss.

Question 26

What does molluscum contagiosum rashes look like?

Answer 26

Localised, unilateral skin condition consisting of multiple well defined, skinny, dome-shaped umbilicated papule.

Question 27

What is molluscum contagiosum?

Answer 27

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.

Question 28

How does drug exanthem look?

Answer 28

Generalised, macular, popular, erythematous rash.

Question 29

Describe drug exanthem.

Answer 29

Appear after a latent period required for induction.
Cell mediated immune reaction.
Most common reaction is macular-papular rash.

Question 30

How does shingles rash look?

Answer 30

Localised dermatomal rash consisting of papule, vesicule, bulla, erosion with crusts.

Question 31

Describe shingles.

Answer 31

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.

Question 32

What are the complications of shingles?

Answer 32

Secondary bacterial infection, paralysis (motor nerve involvement can occur), corneal ulcers and scarring (if ophthalmic division of trigeminal nerve involved), neuralgic pain.

Question 33

How should shingles be treated?

Answer 33

Systemic aciclovir within 2 days of episode and analgesics.