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Micro Anatomy > Integumentary system > Flashcards

Integumentary system Flashcards

1
Q

what is the skin

A
  • Integument = skin.
  • Largest organ in the body.
  • Thin, flat, cutaneous membrane.
  • Main layers are: epidermis, dermis and hypodermis.
  • Integumentary system = Skin and appendages (hair, nail, glands)
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2
Q

what are the functions of the skin

A

*Protection - barrier + immunological.
* Sensation.
* Movement and growth without injury.
* Exocrine - water, urea, ammonia, uric acid.
* Endocrine -vitamin D production.
* Immunity.
* Homeostasis - thermoregulation, water conservation, gas exchange, excretion.

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3
Q

SKIN STRUCTUR the 3 layers

A

EPIDERMIS
* Outermost layer of skin.
* SSK epithelium.
* Provides waterproof barrier and creates skin tone.
* SSK

DERMIS
* Beneath the epidermis.
* Contains connective tissue, hair follicles and sweat glands.
* LOCT
* DICT

HYPODERMIS (SUBCUTIS)
* Deep subcutaneous layer.
* Made of adipose and connective tissue
* Adipose CT

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4
Q

how is skin classified

A

THICK SKIN
* Palms of hands, soles of feet.
* Thick epidermis.
* 5 strata (layers) of epidermis. the extra layer is Stratum lucidum. Other layers are thicker than in thin skin as well
* Sweat glands present.
* Hair and sebaceous glands absent

THIN SKIN
* Covering of the entire body.
* Thin epidermis.
* 4 strata (layers) of epidermis.
* Sweat glands present.
* Hair and sebaceous glands present

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5
Q

what is the epidermis

A
  • Contact with exterior environment.
  • Contains keratinocytes that produce keratin
  • Keratinization → Desquamation.
  • Self generating (50-60 days).
  • Maintains thickness by desquamation.
  • Avascular.
  • Vitamin D synthesis.
  • Thickness determines the skin category.
  • Morphology: Stratified Squamous Keratinizing (SSK).
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6
Q

what are KERATINOCYTES

A
  • Epidermal cell
  • Majority cell type in the epidermis.
  • 90% of skin cells.
  • Arranged in layers (strata).
  • Found in all layers – arise from
    basal layer (stratum basale).
  • Held together by desmosomes.
  • Becomes filled with keratin.
  • Production of lamellar bodies.
  • Life span: 50 – 60 days.
  • Bound to dermis by:
  • Basement membrane
  • Friction (Rete) ridges
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7
Q

MELANOCYTES

A

Cells located in the epidermis
* 5% of skin cells
* No desmosomes – dendritic cells.
* Melanin pigment producing cells.
* Gives colour to skin.
* Protect skin from damaging effectsof ultraviolet radiation (UV).
* Slow replication.
* Number is constant in all races; degree of activity is variable.
* Found between stratum basale and stratum spinosum.

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8
Q

LANGERHANS CELLS

A

Cells located in the epidermis
* Aka. Dendritic cells.
* Cytoplasmic processes.
* Macrophages of the skin, antigen presenting cells.
* Has a role in immunity; antigen presenting cells to T-cells of the immune system.
* Found mainly in the stratum spinosum

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9
Q

MERKEL CELLS

A
  • Aka. Tactile cell.
  • Mechanoreceptors.
  • Cutaneous sensation.
  • Presence of keratin and neurosecretory granules in the cell.
  • Associated with nerve endings.
  • Found in stratum basale.
  • Cells are held together by desmosomes

need a special stain cannot be seen with regular H&E stain

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10
Q

MORPHOLOGICAL LAYERS
OF THE EPIDERMIS

A
  • Stratum corneum -“corny”
  • Stratum lucidum -“clear”
  • Stratum granulosum -“granular”
  • Stratum spinosum -“spiny” or “prickly”
  • Stratum basale -“base”

superficial to deep
old to young

Can’t Let Good Skin Burn

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11
Q

STRATUM BASALE

A
  • Basal layer.
  • One layer of cuboidal or low columnar cells.
  • Repeated mitosis.
  • Majority keratinocytes - contain intermediate keratin filaments that eventually become keratin.
  • Attached to other basale cellsand to cells of the stratum spinosum by desmosomes.
  • Attached to basement membrane by hemidesmosomes
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12
Q

STRATUM SPINOSUM

A
  • Spiny or prickly layer.
  • 8-10 layers of polyhedral keratinocytes with large nuclei.
  • Very prominent desmosomes -
    filled with tonofilaments.
  • Equipped to produce keratin
    and form tonofilaments.
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13
Q

STRATUM GRANULOSUM

A

Granular layer.
* 2-4 layers of keratinocytes filled with basophilic keratohyalin granules in the
cytoplasm.
* Keratinocytes mature and start to degenerate.
* Increase lysosomal activity
* Very thin in thin skin.

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14
Q

STRATUM LUCIDUM

A
  • Clear layer.
  • Flat, closely packed, clear cells.
  • +/- nuclei.
  • Cells are filled with eleidin.
  • Absent in thin skin; prominent in thick skin
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15
Q

STRATUM CORNEUM

A
  • “Corny layer”
  • 20-30 cell layers if thin, flat cells - dead and continually being replaced – barrier
    area.
  • Cell cytoplasm replaced by keratin fiber coated with:
  • Glycophospholipid + keratin fibers = waterproof barrier.
  • Glycophospholipid + keratin
    fibers + desmosones = prevent wear and tear.
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16
Q

KERATINIZATION

A

Process by which cells from stratum basale transform into cells filled with keratin filaments in the stratum corneum.
* Keratinocyte → keratin.

when this goes wrong you can get Epidermolysis bullosa or Lamellar ichthyosis

17
Q

DERMAL EPIDERMAL JUNCTION

A
  • Scalloped margin at the interface of the epidermis and dermis.
  • Formed by interdigitation of
    1. INTERPAPILLARY PEGS – downward projections of the epidermis
    2. DERMAL PAPILLAE – upward projection of the connective tissue from the dermis.
  • DEJ is more apparent in thick skin (hands and palms) where there is a lot of friction – friction rete ridges.
  • Rete ridges enhances the gripping ability of our fingers
18
Q

DERMIS

A
  • Provides mechanical strength.
  • Protection from mechanical injury and compression.
  • Provide nourishment to the epidermis.
  • Plays important role in wound healing.
  • Vascular – thermoregulation.
  • Somatic sensory nerve receptors:
  • Pain, pressure, touch, temperature.
  • Composed of: connective tissue, hair follicles, sweat and sebaceous glands.

Two sublayers:
1. Papillary dermis – LOCT.
* Superficial dermis..
2. Reticular dermis – DICT.
* Deep dermis

19
Q

PAPILLARY DERMIS

A
  • Superficial thin layer of the dermis.
  • Forms the dermal papillae.
  • Interdigitates with the interpapillary peg (epidermis).
  • Forms dermal papillary junction
    (DEJ)
  • Pronounced in thick skin (palms
    and soles).
  • Morphology: LOCT
  • Fine collagen fibers + elastin fibers
20
Q

RETICULAR DERMIS

A
  • Deep thick layer of the dermis.
  • Attachment points:
  • Skeletal muscles (face and scalp)
  • Smooth muscle (arrector pili muscle, scrotum, areolae surrounding nipples, anus).
  • Contains sweat glands, +/- hair follicles and sebaceous glands.
  • Morphology: DICT
  • Thick bundles of collagen fibers + elastin fibers (irregular pattern).
21
Q

EPIDERMAL DERIVATIVES
IN THE DERMIS

A
  • Hair follicles.
    Associated with sebaceous glands; serves as the duct of sebaceous glands.
  • Surface epithelium morphology:
    Stratified squamous
  • Sebaceous glands.
    Associated with:
    1. Arrector pili muscle – smooth muscle.
    2. Hair follicle.
    both make up the pilosebaceous unit
  • Secretion – sebum.
  • Morphology: Simple branched acinar.
  • Sweat glands (eccrine).
  • Apocrine glands
22
Q

SWEAT GLAND (ECCRINE)

A
  • Palms, soles, forehead.
  • Secretion - sweat
  • Evaporation lowers body temperature.
  • Excretes Na+, Cl-, urea, ammonia, uric acid.
  • Morphology: Simple coiled tubular
  • Secretory portion - simple cuboidal
  • Excretory portion -stratified cuboidal
  • Presence of myoepithelial cells in the secretory portion
  • Contractile smooth-muscle like cells that contract and stimulate secretions of exocrine glands.
23
Q

APOCRINE GLANDS

A
  • Axillary, areolae of the breast,
    genital regions.
  • Secretion - Viscid, milky secretion.
  • Morphology: Simple coiled tubular
  • Secretory portion - simple cuboidal
    (budding on the apex)
  • Excretory portion -stratified cuboidal
  • Presence of myoepithelial cells in
    the secretory portion.
  • Functional at puberty
24
Q

DERMIS VASCULATURE

A
  • Numerous blood vessels, lymph vessels and nerves.
  • Glomus bodies-
  • Controls blood flow and thermal regulation in the skin.
  • Blood gets shunted from different areas and flows between small arteries and small veins.
25
Q

SENSORY RECEPTORS

A

PACINIAN CORPUSCLES
* Found deep in the dermis or hypodermis.
* Responds to deep pressure.

MEISSNER’S CORPUSCLES
* Found in the dermal papillae.
* Responds to low frequency stimuli.

RUFFINI’S CORPUSCLES
* Found deep in the dermis and hypodermis of the sole.
* Sensitive to sustained and continuous stress.

26
Q

HYPODERMIS

A
  • Predominately adipose.
  • Interlaced with blood vessels and nerves.
  • It provides the main structural support for the skin. insulating the body from cold and aiding shock absorption.
  • Compartmentalized into lobules by connective tissue (septae).
  • Certain parts of the body contains:
  • Anagen hair follicles, hair follicles, apocrine glands, sweat glands.
  • Skeletal muscles in the face (facial expressions)
27
Q
A

Micro Anatomy (14 decks)

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