ToB S6 - Skin

Question 1

What variation in macroscopic structures of the skin are there?

Answer 1

1) Colour
2) Hair
3) Thickness
4) Laxity/waxiness
5) Oiliness

Question 2

What are the 4/5 layers of skin?

Answer 2

Come Lets Get Sun Burnt

1) Horny layer (stratum corneum)
2) Stratum lucidum (found only in the palms and soles)
3) Stratum granulosum (Granular layer)
4) Stratum spinosum (prickle cell layer
5) Stratum basale (basal layer)

Question 3

What is responsible for skin colour?

Answer 3

Melanin

Question 4

What is alopecia areata?

Answer 4

An autoimmune attack against hair follicles

Question 5

What is vitiligo?

Answer 5

• An autoimmune disease in which the immune system attacks melanocytes, usually in symmetrical localised areas of the skin
• Causes well-demarcated pigmentation
• No clear explanations for the symmetrical nature of vitiligo

Question 6

Describe the main functions of the skin

Answer 6

1) Barrier function of the skin
2) Sensation
3) Thermoregulation
4) Psychosexual communication

Question 7

Describe psoriasis

Answer 7

A disorder of epidermal growth and differentiation

• A very common skin disease (2% of the population)
• Cause is unknown, but runs in families; genetic factors
• Associated with extreme proliferation of the epidermal basal layer
• Causes gross thickening of the stratum spinosum layered excessive production of the stratum corneum
• This manifests clinically as excessive scaling

Question 8

Describe a malignant melanoma

Answer 8

• An aggressive malignant tumour of melanocytes
• Retention of tumour cells above the epidermal basement membrane is associated with a good prognosis
• More penetrating ‘nodular’ melanomas may have a very poor prognosis
• Common moles are benign growths of melanocytes, but may sometimes be difficult to distinguish from melanomas clinically

Question 9

What are melanocytes? Where are they found?

Answer 9

• Dendritic cells of neural crest origin which secrete melanin
• Found in basal layer of epidermis

Question 10

What are Langerhans cells? Where are they found?

Answer 10

• Dendritic cells of bone marrow organ which are antigen presenting cells
• Found in the stratum spinosum

Question 11

Describe the process of keratinocyte differentiation

Answer 11

1) Keratinocytes produced by mitotic division in the stratum basale
2) Terminal differentiation begins in prickle cell layer and keratinocytes loose ability to divide
3) In granular layer, plasma membrane lost and corneocytes form which are destined for the stratum corneum
4) Takes 30-40 days

Question 12

What unique structure is found in the granular layer?

Answer 12

Keratohyalin granules

Question 13

What does the dermis consist of?

Answer 13

1) Dense irregular connective tissue
2) Skin appendages
3) Immediate subcutaneous fat

Question 14

Why is vitiligo less obvious in a caucasian individual?

Answer 14

Paler skin so depigmentation less obvious than in a dark skinned individual