S4 L1 Essentials of Skin Structure and Function Flashcards
What are the main functions of the skin?
- Protective barrier against environmental insults
- Temperature regulation
- Sensation
- Vit D synthesis
- Immunosurveillance
- Cosmesis → appearance
What is erythroderma?
Severe and potentially life threatening condition
‘Total skin failure’
Red (erythromatous), extensive, exfoliative rash
>90% of body surface affected, erythematous and exfoliatitive
What are the erythroderma complications?
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
What are common causes of erythroderma?
Psoriasis
Eczema
Drug
Cutaneous T cell lymphoma
What are the symptoms of erythroderma?
Pruritus- itching
Fatigue
Anorexia
Feeling cold
What are the signs of erythroderma?
Erythematous (red) Thickened Inflamed Scaly No sparing
What are the four main cells present in the epidermis?
Outermost layer
- Keratinocytes → protective barrier
- Langerhan cells → antigen presenting cells - immunosurveillance
- Melanocytes → produce melanin which provides pigment to the skin and protects cell nuclei from UV DNA damage
- Merkel cells → contain specialised nerve ending for sensation
What are layers of the epidermins?
- Stratum corneum (superficial layer)
- Stratum lucidum (only present in thick skin e.g. soles of feet, palms of hands)
- Stratum granulosum
- Stratum spinosum
- Stratum basale (deepest layer)
Each layer represents a different maturation stage of the keratinocytes
What is the rate of cell turnover in the skin?
Turnover is about 30days
What can pathology in the dermis result in?
Change in epidermal turnover e.g. psoriasis
Change in surface of the skin
Change in pigmentation of the skin
What is the dermis?
Thicker layer of the skin
Composed of collagen, elastin and glycosaminoglycans
What is the function of the dermis?
Provides strength and elasticity
Contains immune cells, nerve cells, skin appendages, lymphatics and blood vessels
What are some of the common conditions to the dermis?
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
What are the functions of the sebaceous glands?
Produce sebum → through the pilosebaceous unit
Sebum lubricates the skin
What is acne vulgaris?
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)
What are the eccrine and apocrine glands?
Regulate body temperature
Innervated by sympathetic system
Eccrine → widespread
Apocrine → active following puberty, found in the axillae, areolar, genitalia and anus
What is hair?
Modified keratin Divided into hair bulb and hair shaft 3 main types; - Lanugo → - Vellum → short hair all over body - Terminal → coarse long hair
How does the hair form?
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
What are some common conditions related to hair loss?
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
What is the structure of the nails?
Nail plate (nail) arises from nail matrix at posterior nail fold Rests on nail bed - contains all the capillaries (nourishment)
What are some common nail pathologies?
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
What is psoriasis?
- 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
What are the clinical features of psoriasis?
Symmetrically distributed Red Scaly plaques with well defined edges Scale typically silvery white Common sites- scalp, elbows, knees
What is dermatitis?
- Group of itchy inflammatory conditions characterised by epidermal changes (interchangeable with eczema)
- Acute or chronic
- Different types of dermatitis
What is the difference in presentation between acute and chronic dermatitis?
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
What is the likely pathology of dermatitis?
Complex interactions Genetic predisposition Environmental triggers Immune dysregulation Leading to inflammatory reaction in the skin
How is dermatitis managed?
Identify and tackle contributing factors
Bathing, clothing, irritants, emollients, topical steroids, pimecrolimus cream, antibiotics, antihistamines…
Long term treatment→ moisturising skin, preventing skin getting dry
What is the psychological and social impact of skin conditions?
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
