Basic Skin Biology Flashcards
What are the functions of the skin?
- Protective barrio against environmental insults
- Temperature regulation (thermoregulates)
- Sensation
- Vit D synthesis
- Immunosurveillance
- Cosmesis
What is the most severe emergency presentation?
- Erythematous (Redness)
- Extensive (covering majority of skin)
- Exfoliative: Upper layer of skin is sliding of
Erythematous extensive exfoliative rash
What is erythroderma?
A presentation which results from several skin conditions as a complication
- Total skin failure
What are the complications of erythroderma?
- Hypothermia (loss of thermoregulation)
- Infection (loss of protective barrier) -> sepsis
- Renal failure (insensible losses)
- High output cardiac failure (dilated skin vessels)
- Protein malnutrition (high turnover of skin as loss of top layer of skin)
How much of the body can be affected by erythroderma?
> 90% of body surface area
erythematous and exfoliative
What are causes of erythroderma?
- Psoriasis
- Eczema
- Secondary complication of drugs
- Cutaneous T cell lymphoma (cancer)
What are some symptoms of erythroderma?
- Pruritus
- Fatigue
- Anorexia
- Feeling cold
What some signs of erythroderma?
- Erythematous
- Thickened
- Inflamed
- Scaly
- No sparing (superficial and deep affected)
What are the layers of skin?
Epidermis
Dermis
What are the 4 types of cells in epidermis?
- Keratinocytes - protective barrier
- Langerhan cells- antigen presenting cells
- Melanocytes- produce melanin which provides pigment to the skin and protects cell nuclei from UV DNA damage
- Merkel Cells - contain specialised nerve endings for sensation
What are the 4 layers of the epidermis?
- stratum corneum
- stratum lucidum (in areas of thick skin like palms)
- stratum granulosum
- stratum basale
What stages of maturation do the-epidermal layers represent and what is cell turnover time?
Each layer represent different stage of maturation of keratinocyte
Average epidermal turnover time is 30 days
What can pathology in epidermis cause?
- a) Change in epidermal turnover
- b) Change in surface of the skin
- c) Changes in pigmentation of the skin
Give 2 examples of pathology of the epidermis
- Psoriasis
- Vitiligo
What are common presentation of psoriasis?
- Erythematous
- Scaly
- Plaques
What are common presentation of psoriasis?
- Erythematous
- Scaly
- Plaque
What causes the appearance of psoriasis?
Increased cell turnover
What is vitiligo?
Patches of make skin
Autoimmune disorder
Hypopigmentation in certain parts of the body
Give 2 examples of pathology of the epidermis
- Psoriasis
- Vitiligo
What is the dermis?
Made of collagen, elastin and glycosaminoglycans
Provides strength and elasticity
What is contained in the Dermis?
immune cell
nerve cells
skin appendages
lymphatics
blood vessels
hair bulbs
sweat glands
Give some examples of pathology of the dermis
- Dermatographia
- Acne vulgaris
What is dermatographia?
- raised bumps when touched - wheel
- Oedema in dermal layer causing the bump
What is the role of sebaceous glands?
- Produce sebum through hair follicles (pilosebaceous unit)
- Secretes sebum to skin for lubrication
- Active post puberty
- Stimulated by conversion of androgen to dihydrotestosterone
What causes acne vulgaris?
- Increased sebum production
- Bacterial colinisation
What glands are responsible for regulating body temperature?
Eccrine (widespread)
Apocrine (active following
puberty and are found in
axillae, areolae, genitalia and
anus)
What are Eccrine and Apocrine glands innervated by?
SNS
What is hair made of?
- Each hair consists of modified keratin
- Divided into hair shaft and hair bulb
What are the main types of hair?
- lanugo hair
- vellum hair (short hair all over body)
- terminal hair (coarse long hair)
Each hair follicle enters a growth cycle which has 3 main phases:
anagen
catagen
telogen
If any of these phases disrupted leading to hair loss (e.g. in cancer treatment)
What are some patterns of hair loss?
- Alopecia areata (patchy hair loss)
- Androgen driven male pattern bulging hairloss
What do nails consist of?
- Consists of a nail plate which arises from the nail matrix at the posterior nail fold and rests on the nail bed.
- Nail bed contains blood capillaries
- Many pathologies can cause changes in nails
Some example of pathology affecting nails?
- Lung pathology: nail clubbing
- Iron deficiency anaemia: koilonychia (spoon like nails)
- Skin conditions like eczema/psoriasis can cause thickening of nail, disruption of normal nail plate, separation of nail plate from nail bed
