Skin

Question 1

Alopecia Areata

autoimmune hair loss

Answer 1

• psychosocial impact if effects scalp - especially in women

Question 2

UV induced abnormalities

Answer 2

• sunburn doesn’t occur in black skin
• skin ageing in whites (photoageing)
  skin cancer in whites
• basal cell carcinoma
• malignant melanoma

Question 3

Epidermis

Answer 3

• stratum corneum - (horny layer - barrier - made up of layers of flattened corneocytes)
• granular layer (keratinocytes differentiate into corneocytes)
• prickle cell layer (joined by desmosomes)
• basal layer (keratinocytes mitosis occurs here mainly)

Question 4

Melanocytes

Answer 4

• occurs at intervals along the basal layer of the epidermis
• dendritic - professional antigen presenting cell
• produce melanin - main pigment that gives skin its colour - produces more melanin but the actual cells are not increased in number in black or tanned skin
  Melanosomes lie on the sunny side of nucleus to protect it from UV light

Question 5

Langerhans cells

Answer 5

• dendritic cells of bone marrow origin
• scattered through the prickle cell layer
• highly specialised capacity to present antigens to T lymphocytes
• mediate immune reactions e.g. Allergic contact dermatitis

Question 6

Psoriasis

Answer 6

• abnormal epidermal growth and differentiation
• in 2% of the population
  Extreme proliferation of the epidermal basal layer, causing gross thickening of the prickle cell layer and production of excessive stratum corneum cells (manifesting clinically as excessive scaling)
• loss of fluid, protein, other nutrients, heat
• excessive absorption of potentially harmful exogenous agents especially drugs

Question 7

Allergic contact dermatitis

Answer 7

• Langerhans cells and T lymphocytes

Question 8

Malignant melanoma

Answer 8

• an aggressive malignant tumour (neoplasm) of melanocytes

- retention of tumour cells above the epidermal basement membrane is associated with a good prognosis

Question 9

Vitiligo

autoimmune depigmentation

Answer 9

• psychosocial impact if affects visible areas in dark-skinned raves
• much less noticeable in whites
• immune system attacks melanocytes - usually in symmetrical localised areas of skin

Question 10

Acne

a skin disease affecting sebaceous glands

Answer 10

• sebaceous gland ducts become obstructed
• increased sebum production
• infection with normally harmless skin bacteria

Question 11

Hyperhidrosis

increased sweating

Answer 11

• may affect only the palms and soles

- embarrassing wet hands - substantial problem

Question 12

Barrier function of skin

Answer 12

Stratum Corneum - major barrier preventing percutaneous absorption of exogenous substances
- can be seriously disrupted by many diseases

Question 13

Sensation problems

Answer 13

Due to leprosy and diabetic sensory neuropathy

- minor injuries not noticed - injection leads to loss of tissue

Question 14

Thermoregulation

Answer 14

Vascular thermoregulation
- dilation of skin blood vessels
- constriction of skin blood vessels lead to pallor and heat conservation
(failure can lead to hypothermia)
Thermoregulatory eccrine sweating
- evaporation of eccrine sweat causes cooling
IMPORTANCE IN THE MAINTENANCE OF BODY TEMPERATURE