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
Corny Look Girlfriend Sucks Boyfriend
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)
3 processes that occur in skin inflammation and cardinal signs:
- Vasodilation, ⬆️microvascular permeability & leukocyte migration
- Signs: Rubor (redness), Tumor (swelling), Calor (heat), dolor (pain), functio laesa (loss of capacity to func)
[RA signs]
What is psoriasis? Common triggers?
may be inherited, several fam. members suffer simutaneously
- Autoimmune disease (T-cells and keratinocytes) result in keratinocytes transit time from basale to corneum to reduce greatly (normal 28-40 days, less severe 7-8 days, severe: 2-4 days)
- Triggers: Injury to skin, alcohol, smoking, stress, menopause, medication, other autoimmune disease
*Acanthosis: thickening of epidermal layer
Symptoms and signs of psoriasis
- Signs: pitting (small holes) of nails, onycholysis (seperation of nail from nail bed), psoriatic arthritis
- Symptoms: silvery scale skin (commonly on elbow, scalp, knee, extensor region)
- eczema is flexor region
What is eczema and its causes? Symptoms?
- Dermatitis/chronic skin disease
- Causes: internal (atopic/allergic dermatitis)- asthma, hay fever; external (occupation)- exposure to irritant
- Symptoms: dry, itchy rash, inflammation, bleeding (painful)
- affects quality of life, miss school
- often symptoms triggered by food allergies
What is malignant melanoma and risk factors? Signs?
- Skin cancer
- Risk: genetic predisposition, sun exposure
- Signs: new/change in mole at back/trunk of legs
[nodular: lump on skin, go black to red, lentigo: flat and develop sideways]
What is vitiligo and causes? Symptoms and signs?
- Skin becomes dipigmented
- Causes: autoimmune condition where T cells attack melanocytes OR increased ROS by neuropeptide Y destroy melanocytes (⬆️ by genetic predisposition, presence of melanoma/other autoimmune conditions)
- Symptoms: Pale white patches develop on skin
[segmental (one part of body, due to ROS), non-segemental (bilateral/generalised, due to autoimmune)]
What is alopecia areata? Causes?
- Spot baldness
- Autoimmune disease where body attacks actively dividing hair follicles
[alopecia totalis: lose hair on scalp; universalis: all body hair]
What is acne and symptoms? Causes?
- Inflamed and blocked sebaceous glands: sebum X reach surface due to blockage from dead bac. or bacterial/leukocyte growth in s.gland
- Causes: puberty (stress/menstrual cycle), medication (steroids ⬆️pustule prod.)
