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Physio > Lecture 3- Histology of the Skin > Flashcards

Lecture 3- Histology of the Skin Flashcards

1
Q

Skin Functions

A
  1. Protection against physical/chemical/biological attacks
  2. Water barrier
  3. Thermoregulation (conservation/dissipation of heat)
  4. Defense barrier to microbes
  5. Excretion of salt
  6. Vitamin D synthesis
  7. Sensory organ
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2
Q

General Organization of Skin: the 3 layers

A

3 layers firmly attached to each other

  1. Epidermis: outermost, from ectoderm
  2. Dermis: deeper, from mesoderm
  3. Hypodermis/Subcutaneous layer
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3
Q

General Organization of Skin

A

Surface of palms/soles have narrow epidermal ridges separated by furrows

  • each epidermal ridge corresponds to dermal papilla, are permanent/unique, create finger prints
  • Dermal-epidermal junction has primary epidermal ridge, interlocks w primary dermal ridge, subdivides it into 2 secondary dermal ridges
  • Some dermal papillae project upward and interlock w downward projections from epidermis (Hairless, thick skin)
  • Thin skin has less and smaller dermal papillae
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4
Q

Stratum Basale

A
  • aka stratum germinativum
  • deepest layer, single layer of cuboidal to low columnar cells on basement membrane
  • Have nucleus and keep dividing to replace superficial cells
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5
Q

Stratum Spinosum

A
  • 2nd deepest, made of many layers of polyhedral cells that have desmosomal bridges w other cells
  • contain Langherhans (combat foreign organisms) cells and processes Melanocytes (pigment producing)
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6
Q

Stratum Malpighi

A

-Name for layers 1 and 2, responsible for cell renewal

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7
Q

Stratum Granulosum

A
  • Flat cells that contain Keratohyaline granules

* absent in thin skin`

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8
Q

Stratum Lucidum

A
  • Thin, transparent layer whose cells have eleidin (a transformation product of keratohyalin
  • Cells lack nuclei bc are filled w keratin
  • absent in thin skin
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9
Q

Stratum Corneum

A

-Made of squames that are densely packed w keratin

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10
Q

Keratinocytes

A
  • Most predominant cell type
  • All 5 layers
  • produce keratin (IF protein)
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11
Q

Melanocytes

A
  • Melanin production
  • Deplete w age, skin gets lighter, more prone to skin cancer
  • neural crest
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12
Q

Langerhans Cells

A

-Antigen trapping cells, interact w T cells

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13
Q

Merkel Cells

A
  • tactile sensations

- neural crest

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14
Q

Keratin

A

-IF protein in all epithelium
-a helical, rod shaped
K5 and K14 in basal keratinocytes
K1 and K10 in stratum spinosum

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15
Q

Dermis

A
  • CT deep to epidermis w vessels, hair follicles, sweat glands and sensory receptors
    1. Papillary layer: superfical layer of irregular CT - Dermal ridges -Dermal papillae, capillary loops, Meissners corpuscles -Free nerve endings
    2. Reticular layer: deeper layer of denser irregular CT
  • Thicker layer -Pacinian corpuscles -Ruffinis corpuscles
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16
Q

Blood Supply to Skin

A
  • Role in nutrient supply and thermoregulation
    1. Cutaneous Plexus: arteries and veins found at dermo-hypodermal junction
    2. Sub-papillary plexus: located in papillary layer of dermis, capillary loops extend into papila and result in convective heat loss/epidermis nutrient supply
    3. AV shunts: between 1 and 2. Supplied by sympathetic nerves, restrict flow through superficial plexus to reduce heat loss in extreme cod
17
Q

Epidermis vs Dermis

A

Epidermis: -highly cellular -little ECM -avascular
Dermis: -predominantly ECM
-low proportion of cells
-highly vascularized

18
Q

Sensory Receptors

A

Meissner Corpuscles: Dermal papila, tactile receptor
Merkel Cell: Basal layer of epidermis, tactile receptor
Free nerve endings: no myelin or schwann cells, pain and temp
Ruffini end organs: in skin and joint capsule, stretching
Pacinian corpuscle: hypodermis and deep fascia,, pressure
Peritrichial nerve ending: base of hair follicle, hair movement

19
Q

Hair

A
  • Composed of shaft of cornified cells and a root contained w in hair follicle
  • associated w sebaceous gland, called pilosebaceous unit
  • Arrector pili muscle attaches to hair follicle
20
Q

Hair growth

A

Anagen: Growth period, 80% of hair in anagen phase
Catagen: brief period of follicle regression or involution, 3 weeks
Telogen: inactive phase, 14%

21
Q

Sweat Glands

A
  • Simple, coiled, tubular glands
  • produce sweat delivered to surface via long ducts
  • secretory portions surrounded by myoepithelial cells
22
Q

Sebaceous Gland

A
  • Branched, acinar, holocrine glands
  • produce oily secretion (sebum)
  • secretion delivered into lumen of hair follicle
23
Q

Epidermolyis Bullosa Simplex

A
  • Mutated K5 & K14 (affacts basal keratinocytes)
  • weak keratin filaments
  • blisters in area of trauma
  • mild
24
Q

Epidermolytic Hyperkeratosis

A
  • Mutated K10
  • keratinocytes in spinosum/granulosum lyse in response to trauma
  • thick,scaly skin, blisters
25
Q

Psoriasis

A
  • Increase in proliferating cells
  • decreased mitotic cycle time (7days instead of 20-30)
  • causes epidermal thickness = thick scaly skin
26
Q

Ichthyoses

A

-hereditary
-thickening of corneum
Due to: 1. increased cohesiveness of corneum
2. defective keratinization from keratin gene mutations 3. increased mitotic activity in basal keratinocytes

27
Q

Malignant Melanoma

A

-Skin cancer that stems from melanocytes (in basal layer of epidermis)
Mole: benign cluster of melanocytes, can become malignant and are then melanoma
-most virulent skin cancer

28
Q

Squamous Cell Carcinoma

A
  • Dermal invasion by abnormal cells of epidermis
  • pleomorphism (different cells at different stages) of tumor cells
  • kerartinization w/in cells = pink cytoplasm
29
Q

Bullous Pemphigoid

A
  • Blister formation

- auto-immune response against proteins associated w desmosomes/ hemi-desmosomes

30
Q

Junctional Epidermolysis Bullosa

A
  • Blisters at epidermal basal lamina
  • mild to severe, fatal by 2
  • due to gene mutations for structural proteins
31
Q

Acne Vulgaris

A
  • inflammatory disorder of pilosebaceous unit
  • excessive keratinization w/in the unit causes excessive sebum production = blockage of ducts in follicle
  • anaerobic bacteria grow in accumulated sebum = localized inflammation/neutrophil infiltration

Physio (6 decks)

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