Lecture 19 & 20 - Skin Flashcards
Which area of the hypodermis is thicker in men & women?
Men: abdomen (white adipose) and shoulders (brown)
Women: Hips, thighs & buttocks
*relatively thick on palms and soles
Desc. the structure & function of the hypodermis.
i) Structure: Adipose tissue + loose connective tissue
[also known as superficial fascia = X part of skin]
ii) Function:
- Insulation
- Energy store: generate heat
- Shock absorber
- Hormones: leptin
Why does hypodermis thinning occur?
- Part of the ageing process
- Skin wrinkling + hypothermia
Desc. structure + function of dermis
i) 3 layers:
1. Papillary- upper (loose)
2. Reticular - lower (dense regular connective tissue)
3. Dermal Papillae - interdigitating (have hands that shoot up to reticular, looks like waves)
ii) Function:
- Hair and sweat glands (thermoregulation)
- Sensory receptors
- Give structure to skin
What is the dermis also known as?
- Corium
- W epidermis:cutis
Why does thinning of dermis occur?
- Ageing process, loss of elastin & collagen
What is the structure and func. of epidermis?
Structure:
- No blood vessels
- Five layers
- Held tgt (basally) by hemi-desmosome and (laterally) by adherens junctions
Function:
- Prevent water loss
- Prevent ingress of pathogens
- Protect from UV exposure
Briefly desc 5 layers of epidermis
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1. Stratum Corneum: made of dead keratinocytes (squames), thick on palms and soles, continuously shed
- Stratum Lucidum (transparent layer): only on palms and soles of feet
- Stratum Granulosom: Stratified squamous, has lamellar granules (assemble keratin fibrils), tonofibrils (bundles of keratin fil., has ⬆️Golgi)
- Stratum Spinosum: Cuboidal epithelium (held tgt by desmosome), produce lamellar bodies (first site of keratin synthesis), Langerhans’ cell (present antigen to T lymphocytes/mediate immune response, diff to see)
- Stratum Basale: Tall columnar epithelium, keratinocytes mitosis, melanocytes (melanin by apocrine secretion, diff to see histologically)
Desc. function, location and structure of non-hairy (thick) skin
- Function: prevent abrasion, increase friction btw skin and surfaces/sensation
- Structure: no hair/arrector pili/sebaceous glands, thicker stratum corneum/dermis, more mechanoreceptors
- Location: palms and soles, btw fingers
Compare thick vs thin skin
Thick:
- No hair follicles/no arrector pili/no sebaceous gland
- Stratum lucidum present
- Obvious ridges and furrows on surface (lines)
- Regular shaped dermal papillae
Thin:
- ✅hair follicle/arrector pili/sebaceous gland
- X stratum lucidum
- X obvious ridges and furrows on surface
- Interdigitating dermal papillae
Function of hair
vellus = thin, soft hair; terminal - hard, coarse (hair on head); lanugo = developing fetus
- Thermoregulation: Piloerector lie flat when hot, erect when cold
- Partial barrier to UV rays
- Prevent dust & pathogens entering the body
- Hair growth X continuous, has active and resting phase. Have additional regressive phase (cells X divide and hair papilla separate and new active phase begins)
- During hair growth, nutrients and toxins are incorporated into hair –> hair growth = clues to toxin exposure
List function of mechanoreceptors: (all in dermis)
- Merkel’s disks
- Meissner’s corpuscles
- Ruffini endings
- Pacinian corpuscles
- Krause end bulbs
- Merkel’s disks: (only un-encapsulated) respond to light touch (tickling etc)
- Meissner’s corpuscles: touch and low-frequency vibration
- Ruffini endings: detect stretch & warmth (not so much)
- Pacinian corpuscles: high-frequency vibration
- Krause end bulbs: cold (thermoreceptor)
Desc. structure and func. of nails:
- Structure: made up of only α keratin
- Functions: protection of distal phalanx, enhance precise delicate movement, ⬆️sensitivity of fingertip
*blanch test: press down on fingernail, delayed return of pink colour = hypovolaemia
Function of skin (only green slide)
- Protection and repair
- Epidermis presence of keratin prevent abrasion
- Melanin against UV, Langerhans’ against pathogens - Thermoregulation and excretion of waste products
- Hair arrector pili
- Sweat gland - Lubrication
- Sebaceous gland release sebum (act as water barrier) - Sensation
- Cell mechanoreceptors - Storage
- Hypodermis contain adipose tissue - Vit D synthesis
- Cholecalciferol produced by skin converted in liver and activated to calcitonin/ vit D3 by kidney
Desc basic terminology used: (jus know)
- Papule & Nodule
- Vesicle & Bulla
- Pustule
- Erythema
- Macule
- Patch
- Plaque
- Excoriations and Striae
- Pruritis, Atrophy
- Ichthyosis
- Erosion & Ulcer
- Lichenification & ecchymoses
- Hirsutism & Alopecia
- Papule & Nodule: P (small lump, <5mm), N (large)
- Vesicle & Bulla: V (small water blister), B (large)
- Pustule: pus-filled vesicle
- Erythema: redness
- Macule: non palpable area of discoloration (freckles)
- Patch: macule >2
- Plaque: Palpable flat-topped area (>2cm)
- Excoriations and Striae: E (Scratch), S (stretch)
- Pruritis, Atrophy: P (Itch), A (Thinning)
- Ichthyosis: scaling
- Erosion & Ulcer: E (superficial loss of epidermis), U (deep + dermis)
- Lichenification & ecchymoses: L (thickening), E (bruising)
- Hirsutism & Alopecia: H (too much hair), A (too little)
