Dermatology & Skin Ageing Flashcards
What are the 4/5 layers of the epidermis?
- Stratum corneum
- Stratum lucidum
- Stratum granulosum
- Stratum spinosum
- Stratum basale (deepest)
What are the 2 layers of the dermis?
Papillary (20%)
Reticular (80%) = deep coarse elastin and thick collagen
What is the function of the hypodermis?
Connects skin to underlying tissues
Connective tissue which contains fat, blood vessels + sensory receptors
What is the stratum corneum?
15-30 flattened dead skin cell layers
Mechanical barrier to prevent hydration loss
Renewed every 4-weeks
What layer is only present in hairless thick skin?
Stratum lucidum
Where are the first signs of keratinisation seen?
Stratum granulosum
What is the stratum spinosum?
8-10 layers of keratinocytes which form strong bonds between each other using desmosome
produce keratin
Contain Langerhans cells (immune cells)
What cell types are found in the stratum basale?
Merkels cells (touch receptors)
Melanocytes
What is the function of the stratum basale?
Single layer of basal cells which produce all keratinocytes
How do we achieve a smooth epidermis?
Damaged epidermis responds by increasing production of keratinocytes and lipids = rejuvinated skin and cell to cell communication improved
What 3 pigments contribute to skin colour?
- Melanin (number usually same but amount of pigment varies)
- Haemoglobin
- Carotene (precursor to vit A, stored in stratum corneum)
What are the 2 types of melanin?
Pheomelanin (pink/red)
Eumelanin (yellow/brown/black)
Where are sebaceous glands found?
Dermis
What is lanugo hair?
fine + long, formed from 20 weeks gestation
What is vellus hair?
Covers most of body, light short and fine
What is terminal hairs?
Vellus becomes terminal in puberty in scalp, eyebrows, eyelashes, pubic areas
How do we get goosebumps?
COld environment = arrector pili contract = goose bumps
What are the 3 phases of hair growth cycle?
- Growing phase (80-90% hairs) years on scalp but months on eyebrows
- Resting phase 3-4 wks (10-20% in this phase)
- Shedding phase (less than 1% in this phase)
What are the 2 main types of sweat glands and what are their differences?
Merocrine (ECCRINE) = thin and watery, involuntary nervous system
APOCRINE = thick secretions, active from puberty, driven by adrenaline
What are some of the functions of the skin? (HINT: there’s 7)
- Protection
- Regulation of body temp
- Synthesis of vit D
- Sensory function
- Preventing loss of essential body fluids
- Immunological function
- Absorption
How does melanin function against UV?
UVR is harmful to skin & damages their DNA. Melanin absorbs & dissipates the radiation, reducing DNA damage to skin.
What are the 2 ways the body thermoregulates?
Sweat glands secrete sweat
Blood vessels in skin dilate so circulating blood comes closer to skins surface
What are Merkels disks?
Found near epidermis base
Densely distributed in fingertips and lips
Unencapsulated nerve endings that respond to light touch
What are meissners corpuscles?
Tactile corpusles found in upper dermis but project into epidermis
Respond to fine touch, pressure and low-frequency vibration/flutter
What are ruggini endings?
Bulbous corpuscles found in deeper dermis
Detect skin stretching, joint alterations and warmth
Provide valuable proprioceptive and kinaesthetic feedback, essential for gripping objects and controlling finger position/movement
What are pacinian corpuscles?
Detect rapid mechanical changes in pressure and high frequency vibration
Found in joint capsules, pancreas, breast, genitals
What are some examples of resident skin microflora?
Staphylococcus
Micrococcus
Corynebacterium
What is a biofilm?
Any group of micro-organisms in which their cells stick to each other on a surface
What are the visual differences between intrinsic and extrinsic ageing?
Intrinsic = fine lines, minimal pigment changes, even texture, no skin thickening
Extrinsic = coarse craggy skin, pigmentation, uneven skin texture, premature lines and wrinkles
What % does extrinsic ageing contribute to the ageing process? Of this, how much is from UV?
90%
80% of which is from UVR
What is UVC?
Ultra short wavelength and screened out by atmospheric ozone layer with very little reaching surface of planet
What is the difference between UVA and UVB?
UVA = ageing, can penetrate clothing, glass, cloud
UVB = burning, screened out by glass etc
What are the 2 main differences between fair skin and skin of colour?
- Differences in fibroblasts = increased risk of hypertrophic scars in darker skins
- Differences in distribution & amount of melanin providing a natural UVR protection which delays the features of photoaging in dark skins by approx. 10 years compared to Caucasians
What is melasma? What can contribute to its development?
Skin appears grey-to-brown in colour
Contributers = pregnancy, hormonal drugs, cosmetics containing perfume, stress, sun exposure, use of sun beds
What is beckers naevi?
area of pigmentation covered in hair
Needs referral to dermatologist
What is Type I hypersensitivity?
IgE mediated
Anaphylaxis, urticaria and angioedema
What is Type II hypersensitivity?
Drugs e.g. rifampicin, penicillin, cephalosporin and sulfonamides
Purpuric reaction
What is Type III hypersensitivity?
Vasculitis and can present as ‘serum sickness’ rash and urticaria
What is Type IV hypersensitivity?
Cell mediated delayed hypersensitivity
Contact dermatitis and photoallergic reactions
How do moisturisers contribute to hydration?
- Repair barrier function
- Reduce water loss
- Increase water content
What is SPF rating mean?
measure of how much longer skin covered by sunscreen would take to become erythematous (aka burn)
What are humectant moisturises/how do they work?
Hydrate the skin by drawing water internally from external environment and from deeper epidermis thereby increasing water content of stratum corneum
usually from HA, glycerin, B5 or B3
What are AHA/BHA?
Chemical exfoliators, increase skin cell turnover
AHA = glycolic acid and lactic acid
BHA = salicyclic acid
If someone is finding AHA irritating, what can be used as alternative?
PHAs
Are peptides effective?
Limiting evidence - concerns molecule is too large to cross skin-barrier
How does action of chemical peels differ from microneedling?
Chemical peels chemoexfoliate which increases keratinocyte production rate
Microneedling provokes skin to regenerate and stimulate new keratinocytes + fibroblasts
What is mesotherapy?
Intradermal injection of solution of ingredients which nourish + stimulate the skin to improve skin texture, skin tone and even more pigmentation
What vitamin promotes collagen synthesis?
Vitamin C
Is salicylic acid lipid soluble?
Yes
