Introduction

Question 1

What is the structure of skin?

Answer 1

○ Sub cutis
- Fat energy store
- Insulation
- Fibrous bands anchors skin to fascia
○ Dermis
- Collagen and elastin matrix with mucopolysaccharide gel and also fibroblasts
- Dermal dendritic cells and macrophages
○ Epidermis
- Outer layer
- 3 cells types: keratinocytes the majority of cells, melanocytes and Langerhans cells
○ Melanocytes
- makes melanosomes (collections of melanin)
§ They sit and the dermis-epidermis junction
○ Langerhans cells
§ Process antigens
§ Migrate to lymph nodes to produce an immune response

Question 2

What is the hair cycle?

Answer 2

○ The hair cycle
	- Anagen
		□ Active growing phase
		□ 80-90% of hair
	- Catagen
		□ 2-3 week phase growth stops/ follicle shrinks
		□ 1-3% of hairs
	- Telogen
		□ Resting phase for 1-4 months 
		□ Up to 10% of hairs in a normal scalp
	- After the telogen phase the hair falls out and anagen phase starts again

Question 3

What is the function of skin?

Answer 3

○ Thermoregulation
	- Insulation
	- Heat transfer 
○ Skin immune system
	- Innate functions e.g. sweat 
	- Adaptive functions e.g. antigen presenting cells
○ Barrier
	- Mechanical protection
	- Chemical protection
	- Microorganism protections
	- UV light protection
	- Keeps in water and electrolytes 
	- Keeps in macromolecules 
○ Sensation
	- Touch
	- Temperature
	- Pain
○ Vitamin D synthesis 
	- UV light converts 7-dehydrocholesterol to cholecalciferol 
○ Interpersonal communication
	- Physical appearance
	- Smell 
	- Self identity

Question 4

Why are skin diseases important to people?

Answer 4

○ Disfigurement
○ Discomfort
○ Disability
○ Depression
○ Death

Question 5

What are the external causes of skin problems?

Answer 5

- Photosensitivity 
	□ Commonly caused by medications
	□ Exposed sites affected 
	□ Can be sensitive to UVA, UVB, visible light or a combination of these
- Cold injury 
	□ Frostbite
	□ Chilblains
	□ Skin necrosis
	□ Cold urticaria 
- Trauma
	□ Dermatitis artefacta
	□ Spray can blisters
	□ Suction cups etc.

Question 6

What are the internal causes of skin problems?

Answer 6

- Genetic 
	□ Polygenetic or specific genetic problems
	□ Neurofibromas 
	□ Ichthyosis 
- Drug reaction
	□ Vary in sensitivity
	□ Think of OTC drugs
	□ Take a good history
- Autoimmune 
	□ Bullous Pemphigoid

Question 7

Describe skin lesions

Answer 7

○ Macule: Small (<0.5cm) circumscribed area
○ Patch: large circumscribed area
○ Papule: small (<0.5cm) raised area
○ Plaque: Large raised area
○ Vesicle: small fluid filled
○ Bulla: Large fluid filled sack 
○ Pustule: Small pus filled
○ Abscess: large pus filled
○ Erosion: Loss of epidermis 
○ Ulcer: Loss of epidermis and dermis 
○ Petechiae: small non-blanching rash
○ Purpura: large non-blanching rash

Question 8

How do you investigate skin conditions?

Answer 8

○ If bacterial infections suspected 
	- Charcoal swab
	- Ask for MC and S
		□ Microscopy
		□ Culture 
		□ Sensitivities 
○ If viral infections suspected
	- Viral swab for PCR
	- PCR is pretty sensitivity
	- Can swab vesicle/ bulla if vesicular eruptions
	- If systemic illness can take throat swab
○ If fungal infections suspected
	- Skin scrapings 
	- Nail clippings
	- Hair sample 
	- Fungal cultures 
	- It takes a couple of weeks to grow a sample
○ Skin biopsy
	- Punch biopsy 
	- Same levels of discomfort as a blood test
	- Little bit of stitching afterwards