4.2 Basic Skin Biology Flashcards
What is the function of the skin?
- Protective barrier
- Temperature regulation
- Sensation
- Vitamin D syntehsis
- Immunosurveillance
- Cosmesis- psychological wellbeing of skin
What is erythroderma?
More than 90% of body surface area affected, erythematous and exfoliative
What are the complications of erthyroderma?
Total skin failure
- Hypothermia- loss of thermoregulation
- Infection
- Renal failure- insensible losses
- High output cardiac failure (dilated skin vessels)
- Protein malnutrition (high skin turnover)
What are the causes of erythroderma?
Psoriasis
Eczema
Drugs
Cutaneous T cell lymphoma
What are the symptoms of erythroderma?
Pruritus
Fatigue
Anorexia
Feeling cold
What are the signs of erythroderma?
Erythematous
Thickened
Inflamed
Scaly
No sparing- rash is all over
What are the 3 layers of the skin?
Epidermis
Dermis
Hypodermis
What are the 4 major cell types in the skin?
Keratinocytes
Langerhan cells
Melanocytes
Merkel cells
What do keratinocytes do?
Form a protective barrier
What do langerhans cells do?
Anitgen presenting cells
What do melanocytes do?
Produce melanin
Pigment which absorbs light and protects cell nuclei from UV DNA damage
What do merkel cells do?
Contain specialised nerve endings for sensation
What are the layers of the epidermis?
Come lets get sun burnt
Stratum corneum
Startum lucidum
Stratum granuolsum
Stratum spinosum
Stratum basale
Each layer represents a differnt stage of maturation of the keratinocyte
What is the average epidermal turnover time?
30 days
Where do you find stratum lucidum?
Areas of thicker skin such as palms and soles
What can pathology of the epidermis cause?
Change in:
- Epidermal turnover
- Surface of the skin
- Pigmentation of the skin
How does psoriasis present?
Scaley-silver colour
Plaques
Erythematous
Well defined
How does vitiligo present?
Well defined
Patches of hypo-pigmentation
What is the dermis composed of?
Collagen
Elastin
Glycosaminoglycans
What does the dermis do?
Provides strength and elasticity
What does the dermis also contain?
Immune cells
Nerve scells
Skin appendages
Lymphatics
Blood vessels
What is dermatographia?
Marks on skin stay for long periods of time, so you can write on the skin
What is a wheal?
Discrete, transient raised mark caused by oedema in the dermal layer
What do sebaceous glands do?
Produce sebum through hair follicles
Secretes sebum on to the skin for lubrication
What causes the activation of sebaceous glands?
Puberty
Stimulation by conversion of androgens to dihydrotestosterone
What is associated with acne vulgaris?
Increased sebum production and bacterial colonisation
What are the two types of sweat glands?
Eccrine
- Widespread over body
Apocrine
- Active after puberty
- Found in axillae, areolae, genitalia and anus
What do sweat glands do?
Regulate body temperature
Innervated by sympathetic nervous system
What does a hair consist of?
Modified keratin
Divided into:
Hair shaft
Hair bulb
What are the 3 main types of hair?
Lanugo- covers foetus
Vellum- short hair all over
Terminal- coarse long hair
What are the stages of hair follicle growth?
Anagen
Catagen
Telogen
Disrupted in cancer
What are the two types of hair loss?
Patchy- Alopecia areata
Male pattern baldness- androgen-driven
What are the different parts of a nail?
Nail plate
Arises from the nail matrix at the posterior nail fold
Nail plate rests on nail bed
What part of the nail contains capillaries?
Nail bed
What conditions can affect nails?
Eczema and psoriasis
Thickening and separation of the nail from the bed
Melanoma
Hyperpigmented linear lesion on nail
