Dermatology

Question 1

What are the 4 histological layers of the epidermis?

Answer 1

Stratum Corneum
Stratum Lucidum
Stratum Granulosum
Stratum Spinosum (Thickest layer)
Stratum Basale

Question 2

What are the layers of the Dermis

Answer 2

Papillary Dermis

Reticular Dermis

Question 3

What is the function of Filaggrin?

Answer 3

Produce a natural moisturising factor

Question 4

Why are protease inhibitors in the skin important?

Answer 4

Prevention of breakdown of corneodesmosomes

Question 5

What is the ideal pH of the skin?

Answer 5

5.5

Question 6

Why does the skin need to be maintained at this pH?

Answer 6

1) Low pH switches on protease inhibitors to prevent corneodesmosome breakdown
2) Low pH also stimulates lipid processing, which prevent H2O less

Question 7

What are the main functions of the skin? (6)

Answer 7

1) Barrier to infection
2) Protection against Trauma
3) Waterproofing
4) Protection against UV
5) Thermoregulation
6) Vitamin D Synthesis

Question 8

How does the skin act as a waterproof barrier?

Answer 8

Tight junctions in stratum granulosum, with epidermal lipids and keratin in stratum corneum form an inside-out/outside-in barrier

Question 9

How does skin resist trauma?

Answer 9

Stratified epithelium resists abrasive forces at sites of abrasion

Question 10

How does UV light damage the skin?

Answer 10

Burns, suppress action of Langerhans cells, photo-aging and DNA damage

Question 11

What is the role of 5alpha reductase in dermal adipocytes?

Answer 11

Converts DHEA and androstenedione to 5alpha-dihydrotestosterone

Question 12

What are the 2 types of Melanin?

Answer 12

1) Pheomelanin (red/yellow) (Increases histamine release)

2) Eumelanin (brown/black)

Question 13

How does the skin respond to sunlight?

Answer 13

Immediate Pigment darkening:

1) Photooxidation of existing melanin
2) Redistribution of melanosomes

Question 14

How does the skin act as an immune organ?

Answer 14

1) Keratinocytes secrete cytokines/chemokines which maintain populations of leucocytes
2) Langerhans are APC’s and secrete cytokines

Question 15

What features does the skin have to make it a sensory organ?

Answer 15

1) Merkle Cells (Basal epidermis)
2) Pacinian Corpuscle (pressure)
3) Meissner Corpuscle (Touch)

Question 16

How does the skin help regulate body temperature?

Answer 16

1) Subcutaneous Fat - Insulation
2) Eccrine Sweat Glands - Body Temp
3) Cutaneous blood flow and Hair