Structure and Function of the Skin

Question 1

Describe skin

Answer 1

Largest organ in the body
Contains adnexal structures - hair, nails, glands and sensory structures
Important role in protection, homeostasis and transmission of sensations

Question 2

What are the layers of the skin?

Answer 2

Skin - epidermis and dermis
Subcutaneous tissue below

Question 3

Describe the process of cell development in the skin

Answer 3

1. Stratum basale - cells divide by mitosis and some newly formed cells become superficial strata
2. Stratum spinosum - keratin fibres and laminar bodies accumulate
3. Stratum granulosum - keratohyalin and hard envelope form
4. Stratum lucidum - dead cells lie within keratohyalin
5. Stratum corneum - dead cells with hard protein envelope

Question 4

Describe the nail anatomy

Answer 4

Hyponychium
Nail plate
Lateral nailfold
Nail bed
Lunula
Cuticle
Proximal nailfold
Nail matrix

Question 5

What are the 3 stages of the hair cycle?

Answer 5

Anagen
Catagen
Telogen

Question 6

What is the anagen phase?

Answer 6

Active growing phase
80-90% of hair
Where chemo effects

Question 7

What is the catagen phase?

Answer 7

2-3 weeks phase growth stops/ follicles shrink
1-3% of hairs

Question 8

What is the telogen phase?

Answer 8

Resting phase for 1-4 months
Up to 10% of hairs in a normal scalp

Question 9

What are the functions of the skin?

Answer 9

Thermoregulation
Skin immune system
Barrier
Sensation
Vitamin D synthesis - UV light converts 7-dehydrocholesterol to cholecalciferol
Interpersonal communication

Question 10

Describe the epidemiology of skin disease

Answer 10

22-30% of population affected
50% skin cancer/ lesions
25% require surgical procedure

Question 11

Why is skin disease important?

Answer 11

Disfigurement, discomfort, disability, depression and death

Question 12

What are some external causes of skin disease?

Answer 12

Temp., UV, chemical, infection and trauma

Question 13

What are some internal causes of skin disease?

Answer 13

Systemic disease, genetics, drugs and infection

Question 14

What are some cold injuries to skin?

Answer 14

Frostbite, chilblains, skin necrosis and cold urticaria

Question 15

What is an example to trauma causing skin disease?

Answer 15

Dermatitis Artefacta - self induced trauma

Question 16

What is an example of an autoimmune disease causing skin disease?

Answer 16

Bullous pemphigoid

Question 17

What is a macule and a patch?

Answer 17

Macule -Small flat circumscribed area
Patch - larger flat circumscribed area

Question 18

What is a papule and a plaque?

Answer 18

Papule - small raised area
Plaque - larger raised area

Question 19

What is a vesicle and a bulla?

Answer 19

Vesicle - small fluid filled
Bulla - large fluid filled

Question 20

What is a pustule and an abscess?

Answer 20

Pustule - small pus filled
Abscess - large pus filled

Question 21

What is a erosion and an ulcer?

Answer 21

Erosion - loss of epidermis
Ulcer - loss of epidermis and dermis

Question 22

Describe a macule

Answer 22

Non-palpable change in skin colour with distinct borders

Question 23

Describe a papule

Answer 23

Solid lesion less than 1cm in diameter

Question 24

Describe a nodule

Answer 24

Palpable lesion more than 1cm in diameter which is taller then it is wide
Ex. neurofibromatosis and rheumatoid nodules

Question 25

What is an example of an erosion?

Answer 25

Toxic epidermal necrolysis - severe drug reaction

Question 26

What is an example of an ulcer?

Answer 26

Pyoderma gangerosum

Question 27

What is distribution?

Answer 27

How skin lesions are scattered or spread out May be isolated or multiple Localised, generalised, symmetrical...

Question 28

What are the most common skin conditions?

Answer 28

Acne, psoriasis, rosacea, skin lesions, urticaria, warts, leg ulcers, scalp/ nail disorders, eczema and infections

Question 29

What are some conditions which can have cutaneous signs?

Answer 29

Erythema nodosum, sarcoidosis, vasculitis, malignancy and auto-immune conditions

Question 30

What is a skin change which shows hyperlipidaemia?

Answer 30

Eruptive xanthoma

Question 31

Describe acanthosis nigricans

Answer 31

Associated with insulin resistance, obesity and malignancy Flexural distribution Hyperkeratosis and hyperpigmentation papules Velvety appearance

Question 32

Describe thyroid skin disease

Answer 32

Pretibial myxoedema 5% of Graves disease Same process behind eyes - mucinosis

Question 33

What are some investigations in dermatology?

Answer 33

Bacterial infection - charcoal swab and ask for MC&S (microscopy, culture and sensitivities) Viral - Swab for PCR, swab vesicle, and throat swab Fungal - skin scrapping, nail clipping and hair sample

Question 34

What is a simple way to take a skin biopsy?

Answer 34

Punch biopsy Takes all 3 layers of the skin Numb with local anaesthesia