Week 1 Downing - Histology of Skin/Integument Flashcards

1
Q

What are the three components of the Integument?

A
  1. Epidermis
  2. Dermis
  3. Hypodermis
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2
Q

What are the four epidermal layers in order from bottom to top?

A
  1. Stratum germinativum (basale)
  2. Stratum spinosum
  3. Stratum granulosum
  4. Stratum corneum
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3
Q

What epidermal layers are mitotically active?

A
  • Stratum germinativum
  • Stratum spinosum
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4
Q

Where is the Stratum germinativum (basale) located?

A
  • Deepest layer of epidermis
  • Adjacent to the basal lamina
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5
Q

Where is the Stratum spinosum located?

A

Immediately above the Stratum germinativum (basale)

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6
Q

What is the structure of the Stratum germinativum (basale)?

A
  • Single layer of cuboidal or columnar cells
  • Hemidesmosomes along cell membrane that attach to basement membrane
  • Contain many polyribosomes and intermediate filaments due to mitotic activity
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7
Q

What is the structure of the Stratum spinosum?

A

Prickle cell layer

  • Several cell layers deep
  • Polygonally shaped cells
  • numerous desmosomes
  • bundles of intermediate filaments (tonofibrils)
  • membrane-bound lamellar bodies containing lipids
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8
Q

What is the structure of the Stratum granulosum?

A
  • 3-5 cell layers thick
  • flattened polygonally-shaped cells
  • keratohyalin granules in cytoplasm
  • nucleus pyknotic (dying)
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9
Q

What is the structure of the Stratum corneum?

A
  • Variable number of cell layers
  • Clear, dead, flattened, and fused cells
  • Cytoplasm is keritinized
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10
Q

Where is the Stratum granulosum located?

A
  • above stratum spinosum
  • below stratum corneum
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11
Q

Where is the Stratum corneum located?

A
  • Outermost layer of epidermis
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12
Q

What are the two phases of Keritinization?

A
  • Synthetic phase
  • Degradative phase
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13
Q

What happens during the Synthetic phase of Keritinization?

A

Form:

  • Intermediate filaments
  • Membrane coating granules
  • Keratohyaline granules (filaggrin & trichohyalin)
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14
Q

What occurs during the Degradative phase of Keritinization?

A
  • Membrane coating granule discharge
    • form lipid layer
  • Lysosomal degradation of organelles
  • Consolidation of filaments and keratohyalin into a fibrous amorphous mass = KERATIN!
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15
Q

What are the three layers of the dermis?

A
  1. Papillary layer (vascular/nervous papillae)
  2. Reticular layer
  3. Langer’s lines
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16
Q

Where is the papillary dermis located?

A
  • uppermost layer of the dermis
  • primary ridges and secondary ridges extend into epidermis forming dermal papillae
    • increase surface area between dermis & epidermis
    • makes secure adherence between layers
17
Q

What is the structure of the papillary dermis?

A
  • Loose connective tissue
    • collagen, some reticular/elastic fibers
  • Vascular papillae
    • capillary loop projections
  • Nervous papillae
    • Meissner’s corpuscles
    • Pacinian corpuscles
18
Q

Where is the reticular dermis located?

A
  • the lower layer of the dermis
  • found under the papillary dermis
19
Q

What is the structure of the reticular dermis?

A
  • composed of dense irregular connective tissue with densely packed collagen fibers
    • type I collagen
    • some reticular fibers
  • primary location of dermal elastic fibers
20
Q

How are secondary dermal ridges formed?

A
  • Downward projection of epidermis in primary ridge
    • projection of epidermis = rete peg
21
Q

What are Langer lines?

A
  • Direction of fibers in reticular dermiscreates lines of skin tension
  • Differ in different regions of the body
  • Surgical incisions gape less when parallel to these lines (less scarring
22
Q

What is the hypodermis?

A
  • Superficial fascia
  • Not considered part of the skin
  • Frequently large accumulations of fat cells
23
Q

Where is the hypodermis located?

A

Below the dermis

24
Q

What is the structure of the hypodermis?

A
  • Loose connective tissue
  • Fat cells

(Fat cells absen in hypodermis of eyelids, penis, and scrotum)

25
Q

How is thick skin differentiated from thin skin?

A
  • Based on epidermal thickness
    • dermis is thin in both types
26
Q

Where is thick skin present in the human body?

A

Palms of hands & Soles of feet

27
Q

Where is thick dermis present in the human body?

A

Skin of back

28
Q

How is melanin formed?

A
  • Rough ER produces tyrosinase
  • Golgi packages tyrosinase enzymes in a membrane-bound vesicle = pre-melanosome
  • Tyrosine + Tyrosinase → DOPA
  • DOPA + Tyrosinase → Melanin
29
Q

Where are melanocytes found?

A

Usually present in the Stratum germinativum (basale) layer of the epidermis.

30
Q

What happens to melanin granules after tyrosinase activity is halted?

A
  • Melanosomes create branches/processes off of melanocyte
  • Processes of melanocytes are insinuated between other epidermal cells
  • Melanosomes are eventually donated to adjacent epidermal cells
31
Q

What is skin pigmentation based on?

A
  • Color of skin itself (carotenes) = yellow
  • Blood capillaries = red/pink
  • Varying amounts of melanin = brown
32
Q

What are the three layers of vascular supply in the dermis called?

A
  1. Subcutaneous arteries & veins (deep)
  2. Rete cutaneum (cutaneous plexus)
  3. Rete subpapillare (subpapillary plexus)
33
Q

Where are the Rete cutaneum (cutaneous plexus) blood vessels located?

A
  • Between reticular layer of dermis and subcutaneous tissue
  • dermal-hypodermal junction
34
Q

Where are the Rete subpapillare vessels located?

A

In papillary layer of the dermis

(supply blood to papillary loops)

35
Q
A