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2.7 BRS Dermatology > Dermatology I > Flashcards

Dermatology I Flashcards

1
Q

What are the 4 layers of the skin?

A
  1. Epidermis —> keratinocytes
  2. Basements membrane
  3. Dermis —> fibroblasts
  4. Subcutaneous fat
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2
Q

What are the 4 layers of the epidermis and how do they develop?

A
  1. Stratum corneum
  2. Stratum granulosum
    (Stratum lucidum —> palms and soles - thicker skin
    - no nuclei or organelles)
  3. Stratum spinosum
  4. Basal layer
    - Progressively differentiate from basal layer - 30 days
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3
Q

What are the 4 types of intercellular junctions in the epidermis?

A
  1. Gap - connexons connect keratinocytes
    —> cell synchronisation
    —> cell differentiation
    —> cell growth
    —> metabolic coordination
    - connexons connect keratinocytes
  2. Adherens
  3. Tight —> barrier integrity
    —> cell polarity
  4. Desmosomes - major —> cells withstand trauma
    - anchor keratin intermediate
    filaments to membrane
    —> bridge keratinocytes
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4
Q

What are the 4 cell types in the epidermis?

A
  1. Fibroblasts
  2. Melanocytes —> melanin pigment stored in
    melanosomes to keratinocytes
    - dendritic
    - same number in all skin types
  3. Langerhans —> antigen-presenting
    - dendritic
  4. Merkel cells —> mechanosensory receptors
    - among basal layer —> connect to
    sensory nerve
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5
Q

What is the structure of the dermis? (3)

A
  1. Papillary dermis
  2. Reticular dermis
  3. Covered in ECM
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6
Q

What are the non-cellular components of the dermis? (in ECM)

A
  1. Proteins —> main component
    • Collagen —> 85% of dermis
      - types I and II
    • Elastic fibres —> 2%
      - fibrillin and elastin
  2. Glycoproteins —> cell adhesion and motility
    - fibronectin, fibulin and integrins
  3. Ground substance —> between collagen and elastic
    - glycosaminoglycan and
    proteoglycan
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7
Q

What are the 2 cell types in the dermis?

A
  1. Fibroblasts
  2. Immune cells:
    • Histiocytes
    • Mast cells
    • Neutrophils
    • Lymphocytes
    • Dermal dendritic cells
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8
Q

What is the vasculature of the skin?

A
  1. Superficial vascular plexus at top of dermis
  2. Deep vascular plexus near bottom of dermis
    - No vasculature in epidermis
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9
Q

What are the 2 types of glands in the skin?

A
  1. Eccrine = direct secretion to surface
    —> cholinergic and adrenergic stimulation
  2. Apocrine = secretion to hair follicle
    —> adrenergic stimulation
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10
Q

What are the 6 types of receptors in the skin?

A
  1. Meissner Corpuscle —> Light touch, slow vibration
    • Finger pads, lips (thick hairless skin)
  2. Ruffini Corpuscle —> Skin stretch, slippage
    • Fingernails
  3. Pacinian Corpuscle —> Deep pressure, vibration
    • Hands, feet (dermal papillae)
  4. Merkel cell (unencapsulated) —> Light sustained
    touch
  5. Thermoreceptor —> Temperature
  6. Free nerve endings —> Light touch
    —> Pain (nociceptors)
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11
Q

What are the 5 sensations sensed by skin receptors?

A
  1. Light touch —> Meissener, Merkel, free
    - Aβ fibres
  2. Touch/pressure —> Merkel, Ruffini, Pacinian, free
    - Aβ, Aδ fibres
  3. Vibration —> Meissener, Pacinian
    - Aβ fibres
  4. Temperature —> Thermoreceptor
    - Aβ, C fibres
  5. Pain —> Nociceptor (free)
    - Aδ, C fibres
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12
Q

What are does the skin microbiota compose of?

A
  1. Bacteria —> 1mn / cm^2
    • Acintobacteria, firmicutes, bacteroidetes,
      proteobacteria
  2. Fungi
  3. Viruses
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13
Q

What are the 6 functions of skin?

A
  1. Physical barrier
  2. Immunological barrier
  3. Thermoregulation
  4. Sensation
  5. Metabolism (vit D)
  6. Aesthetics
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14
Q

What are the 3 components of skin acting as an immunological barrier?

A
  1. Determine immune response:
    • Langerhans cells —> sense environment
    • No danger: Treg expansion and activation
      Danger: Extend denritic processes up through
      tight junctions to stratum corneum —>
      initiate innate (when TLRs sense PAMPs)
      —> induce adaptive
  2. Antimicrobial peptides:
    • Defensins and cathelicidins from keratinocytes —>
      antibiotic
  3. Immune surveillance:
    • Tissue-resident T cells
      Macrophages
      Dendritic cells
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15
Q

What are the 3 ways skin acts as a physical barrier?

A
  1. Prevent water and protein loss:
    • Cornified cells around stratum corneum
  2. Cushioning
    • Subcutaneous fat
  3. UV barrier
    • Melanin in basal keratinocytes
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16
Q

What are the 2 ways skin performs thermoregulation?

A
  1. Vasodilation/constriction (of plexuses) —> heat loss
  2. Eccrine sweat glands —> cooling
17
Q

What are the 3 metabolic functions of the skin?

A
  1. Vitamin D synthesis
  2. Calorie reserve —> subcutaneous fat (80% body fat)
  3. Leptin released by white adipose tissue (hunger)
18
Q

What are the 3 skin appendages?

A
  1. Pilosebaceous unit (hair)
  2. Sweat glands
  3. Nails
19
Q

What are the 6 functions of hair?

A
  1. Protection
  2. Sebum release
  3. Apocrine sweat release
  4. Thermoregulation
  5. Social interactions
  6. Epithelial and melanocyte stem cells
20
Q

What happens in the hair cycle? (3)

A
  1. Anagen —> formation and growth
    • lasts 2-6 years
    • 85% of hair
  2. Catagen —> regression
    • lasts 3 weeks
    • 1% of hair
  3. Telogen —> resting (before loss)
    • lasts 3 months
    • 15% of hair
20
Q

What are the 2 types of hair?

A
  1. Terminal - scalp, eyebrows, eyelashes
  2. Vellus - rest of body
21
Q

What is the structure of the pilocebaceous unit?

A
  1. Follicle
    • Bulb at bottom attaches to dermal papillae
    • Contains hair shaft
  2. Sebaceous gland
    • Joins in middle —> sebum
  3. Arrector pili
    • Joins follicle to dermis —> extends at angle
22
Q

What are the 2 sections of a strand of hair?

A
  1. Infundubulum = above sebaceous gland
  2. Isthmus = sebaceous gland to arrector pili joining
    - trichilemmal keratinisation
23
Q

What are the 2 types of sweat glands?

A
  1. Eccrine —> sweat directly to skin surface
  2. Apocrine —> sweat to hair follicle
24
Q

How does a nail plate form?

A

Proliferation and differentiation of nail matrix keratinocytes —> lose nuclei, filled by keratins, adherent-cytoplasm (+ have melanin)

  • matrix under proximal nail fold
    above distal phalynx bone
  • 1-3mm/month
  • extends from proximal nail fold
    lined by lateral nail folds
    attaches to nail-bed
    detaches at hyponychium
25
Q

What are the 5 functions of nails?

A
  1. Protect distal phalynx
  2. Counterpressure effect —> balance
  3. Dexterity
  4. Sensory discrimination
  5. Scratching
26
Q

What is the structure of nails? (5)

A
  1. Proximal nail fold
  2. Lateral nail folds
  3. Hyponichium (detaches from nail-bed)
  4. Nail-bed
  5. Lunula (visible semi-circle of matrix)

2.7 BRS Dermatology (2 decks)

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