S4 L1 Essentials of Skin Structure and Function

Question 1

What are the main functions of the skin?

Answer 1

1. Protective barrier against environmental insults
2. Temperature regulation
3. Sensation
4. Vit D synthesis
5. Immunosurveillance
6. Cosmesis → appearance

Question 2

What is erythroderma?

Answer 2

Severe and potentially life threatening condition
‘Total skin failure’
Red (erythromatous), extensive, exfoliative rash
>90% of body surface affected, erythematous and exfoliatitive

Question 3

What are the erythroderma complications?

Answer 3

Total skin failure

• Hypothermia → loss of thermoregulation
• Infection → loss of protective barrier leads to sepsis
• Renal failure → insensible losses
• High output cardiac failure → dilated skin vessels
• Protein malnutrition → high cell turnover of skin cells

Question 4

What are common causes of erythroderma?

Answer 4

Psoriasis
Eczema
Drug
Cutaneous T cell lymphoma

Question 5

What are the symptoms of erythroderma?

Answer 5

Pruritus- itching
Fatigue
Anorexia
Feeling cold

Question 6

What are the signs of erythroderma?

Answer 6

Erythematous (red) 
Thickened 
Inflamed 
Scaly 
No sparing

Question 7

What are the four main cells present in the epidermis?

Answer 7

Outermost layer

1. Keratinocytes → protective barrier
2. Langerhan cells → antigen presenting cells - immunosurveillance
3. Melanocytes → produce melanin which provides pigment to the skin and protects cell nuclei from UV DNA damage
4. Merkel cells → contain specialised nerve ending for sensation

Question 8

What are layers of the epidermins?

Answer 8

1. Stratum corneum (superficial layer)
2. Stratum lucidum (only present in thick skin e.g. soles of feet, palms of hands)
3. Stratum granulosum
4. Stratum spinosum
5. Stratum basale (deepest layer)
   Each layer represents a different maturation stage of the keratinocytes

Question 9

What is the rate of cell turnover in the skin?

Answer 9

Turnover is about 30days

Question 10

What can pathology in the dermis result in?

Answer 10

Change in epidermal turnover e.g. psoriasis
Change in surface of the skin
Change in pigmentation of the skin

Question 11

What is the dermis?

Answer 11

Thicker layer of the skin

Composed of collagen, elastin and glycosaminoglycans

Question 12

What is the function of the dermis?

Answer 12

Provides strength and elasticity

Contains immune cells, nerve cells, skin appendages, lymphatics and blood vessels

Question 13

What are some of the common conditions to the dermis?

Answer 13

Dermatographia → run finger over the skin results in mark appearing
Wheal → more discrete presentation
Urticaria → Raised itchy rash that appears on the skin
Oedema in the dermal layer of the skin

Question 14

What are the functions of the sebaceous glands?

Answer 14

Produce sebum → through the pilosebaceous unit

Sebum lubricates the skin

Question 15

What is acne vulgaris?

Answer 15

Consequence of activation of the sebaceous glands
Particularly active after puberty
Stimulated by conversion of androgens to dihydrotestosterone
Sebum on the skin traps the bacteria (colonisation) results in acne
Huge impact on people
Presentation→ inflamed papules, pustules and nodules, non-inflamed comedones and pseudocysts
Usually on face, neck, chest and back (can spread to lower body)

Question 16

What are the eccrine and apocrine glands?

Answer 16

Regulate body temperature
Innervated by sympathetic system
Eccrine → widespread
Apocrine → active following puberty, found in the axillae, areolar, genitalia and anus

Question 17

What is hair?

Answer 17

Modified keratin 
Divided into hair bulb and hair shaft 
3 main types;
- Lanugo → 
- Vellum → short hair all over body 
- Terminal → coarse long hair

Question 18

How does the hair form?

Answer 18

Growth cycle
3 main phases
1. Anagen → active stage of hair growth
2. Catagen → transition phase
3. Telogen → terminal phase, hair becomes club doesn’t grow any further
- Disruption to one of these stages or imbalance between loose and growth leads to hair loss

Question 19

What are some common conditions related to hair loss?

Answer 19

Alpecia areata → patchy/spots, random, males and females

Male pattern baldness→ hormone directed (androgen), 5th and 6th decade of life, usually but not always in men

Question 20

What is the structure of the nails?

Answer 20

Nail plate (nail) arises from nail matrix at posterior nail fold 
Rests on nail bed - contains all the capillaries (nourishment)

Question 21

What are some common nail pathologies?

Answer 21

Manual workers- common trauma
Ingrowing toenails
Fungal nail infections- thickened, discoloured nail
Severe eczema, psoriasis → thickening of nail plate, separation of nail plate from bed, splitting of nail
Can show severe pathologies → melanoma etc

Question 22

What is psoriasis?

Answer 22

• Chronic inflammatory skin condition
• Clearly define, erythematous (red), scaly plaques (thickened skin)
• 2-4% of males and females, start at any age
• Lifelong, fluctuating in extent and severity
• Immune mediated inflammatory disease
• Different types

Question 23

What are the clinical features of psoriasis?

Answer 23

Symmetrically distributed 
Red 
Scaly plaques with well defined edges 
Scale typically silvery white
Common sites- scalp, elbows, knees

Question 24

What is dermatitis?

Answer 24

• Group of itchy inflammatory conditions characterised by epidermal changes (interchangeable with eczema)
• Acute or chronic
• Different types of dermatitis

Question 25

What is the difference in presentation between acute and chronic dermatitis?

Answer 25

Acute → rapidly evolving red rash which maybe blistered and swollen
Chronic → longstanding irritable area, often darker than the surrounding skin thickened (lichenified) and much scratched

Question 26

What is the likely pathology of dermatitis?

Answer 26

Complex interactions 
Genetic predisposition 
Environmental triggers 
Immune dysregulation 
Leading to inflammatory reaction in the skin

Question 27

How is dermatitis managed?

Answer 27

Identify and tackle contributing factors
Bathing, clothing, irritants, emollients, topical steroids, pimecrolimus cream, antibiotics, antihistamines…
Long term treatment→ moisturising skin, preventing skin getting dry

Question 28

What is the psychological and social impact of skin conditions?

Answer 28

Severe psychological and social impact
Severe mental health problems
Stigmatisation
Decreased body image, lower self-esteem, withdraw from social situation, embarrassed, avoid exposing skin
Lead to depression
People with skin conditions often are aware of when people avoid touching them → person feels ashamed and even worse