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Musculoskeletal System > Integumentary 1 > Flashcards

Integumentary 1 Flashcards

1
Q

What are the two layers of the integumentary system?

A

-epidermis and dermis

Epidermis-epithelium + cells

  • keratinized stratified squamous epithelium
  • derived from ectoderm

Dermis- dense connective tissue
-derived from mesoderm

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2
Q

What is the hypodermis?

A

Found deep to (beneath). The dermis

-often referred to as the subcutaneous fascia in gross anatomy

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3
Q

What is contained in the hypodermis?

A

Contains variable amounts of adipose tissue (panniculus adiposus) arranged in lobules and separated by connective tissue septa

Can find hair follicles, glands and mechanireceptors in this layer

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4
Q

In what countries are the hypodermis thick?

A

Cold countries

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5
Q

What. Are the associated appendages of the hypodermis?

A
  • hair follicles
  • sweat glands
  • sebaceous glands
  • nails
  • mammary glands
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6
Q

What are the functions of skin?

A

Barrier

  • immunological role- presents antigens to the lymphatic tissue
  • homeostasis-regulation of body temperature and water loss
  • Sensory information- samples the external environment and relays this information to the nervous system
  • Endocrine functions- secretes hormones, cytokines and growth factors, converts vitamin D into its hormonally active from D3

Excretion- secretes sweat and other products from the body

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7
Q

What is the largest population of cells in the integumentary system?

A

Keratinocytes

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8
Q

What are the pigments producing cells in the integumentary system?

A

Pigment producing cells of the epidermis

-makes up about 5% of the cell population

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9
Q

What is the merchankreceptor in the epidermis?

A

Merkel cells
Merchanoreceptors

  • associated with sense nerve endings
  • constitutes 6%-10% of cells in the epidermis
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10
Q

What are langerhans cells?

A

Antigen presenting cells (APC’s)
-plays a role in the immunological function of skin

-accounts fir 2%-5% of cells

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11
Q

What are keratinocytes?

A
  • Constitutes most of the cell types (85%) of the epidermis

- Differentiates. From basal layer, and continues throughout all layers of the epidermis

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12
Q

What are the functions of keratinocytes?

A
  • produces keratin (cytokeratin) - mainly the keratinocytes of stratum basale
  • produce keratohylain granules- cells in spinosum & granulosum
  • contributes to the formation of the epidermal water barrier
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13
Q

Where are melanocytes located?

A

Melanocyte to keratinocytes ratio 1:4 to 1:10

-varies according to the region of the body

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14
Q

Where are melanocytes located?

A

Located in the basal layer (stratum basale)

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15
Q

What are the origins and formations of melanocytes?

A

Originates from neural crest

  • Appear clear with elongated nuclei
  • Multiple cytoplasmic processes that extend between keratinocytes
  • 1 melanocytes can communicate with up to 40 keratinocytes
  • No desmosome connections but are attached to the basal lamina via hemidesmosomes like structures
  • lacks keratin filaments
  • Cytoplasm contains oval dark staining premelanosomes (responsible for the synthesis of melanin)
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16
Q

What are the functions of melanocytes?

A
  • Produce melanin that is transferred to surrounding keratinocytes (cytocrine secretion)
    • UV protection
  • Skin color-amount and ratio of melanin types present
    • Lighter skinned individuals have increased melanin degradation

-Oxidation of tyrosine to 3,4 dihydroxyphenylalanine (DOPA) and subsequent transformation of DOPA into melanin

17
Q

How are mature melanosomes formed?

A

Premelanosomes formed by Golgi-transformed into early melanosomes

Contain tyrosinase molecules and small amounts of melanin

Conversion. Into melanin gradually occurs until the. Mature melanosome is forned

18
Q

What are the factors associated with skin pigmentation?

A

-UV Radiation- melanin production is influenced by the surrounding keratinocytes in response to UV radiation

  • Melanin distribution- dispersed differently in light vs dark skinned persons
    • Light skinned persons- concentrated in stratum basale
    • Dark skinned persons- dispersed throughout stratum basale and spinosum

Type of melanin-each type of melanin has a different function and is driven by different genetic factors

  • The pigment produced by melanocytes consist of two different forms+eumelanin and pheomelanin
    • The ratio between the two determines skin and hair color
19
Q

Describe eumelanin

A

Protection against UVR damage

  • scatter and absorb UV rays and eliminate UV generated free radicals
  • Degrades faster in lighter skinned individuals
20
Q

Describe pheomelanin

A

-Allows a greater amount of light to pass through thereby increasing vitamin D production at altitudes where light intensity is low

Found more commonly in atypical nevi and melanomas

Increased oxidative damage

21
Q

Describe langerhans origins

A

Originate from common lymphoid progenitor (CLP)

-Present in all epidermal layers but most easily recognized in stratum spinosum

22
Q

What is the function of langerhans?

A

Immunological role

  • Encounters, processes and expresses antigens (Antigen presenting cell(APC))
  • Migrates to the lymph node to present the antigen to T-lymphocytes
  • Express both MHC-1 and MHC-2 and receptors for IgG
  • Involved in delayed type hypersensitivity reactions
23
Q

What do Langerhans look like under light microscopes?

A

Nucleus stain well with hematoxylin (blue)

Cytoplasm is clear

24
Q

Describe the TEM structure

A

Nuclear membrane- indented structure making the nuclear profile uneven (“N” On right TEM image)

Possesses tennis racquet shaped granules (Birbeck granules)-

  • small linear (rod-like) structure with a bublbous expansion (vesicle) at one end
  • regular cross striations
  • function unclear but may be part of the endosome system
25
Q

Describe the structure of Merkel cells

A
  • least numerous cell structure after langerhans cell
  • most abundant in skin where sensory perception is acute (fingertips )
  • closely associated with the expanded terminal bulb of afferent myelinated nerve fibers- Merkel’s corpuscle
26
Q

What is the function of Merkel cell?

A

Detect touch sensations

Have desmosomes and contain keratin filaments

Nucleus is lobed

Cytoplasm contains neurosecretory granules

Possess antigenic markers of both epidermal and neural type

27
Q

What is the distinction between thick and thin filaments?

A

This is made on the thickness of the epidermis

28
Q

Summarize thick skin

A
  • found only in the palms and soles
  • usually hairless and much thicker epidermis
  • carries a stratum lucidum
29
Q

Summarize thin skin

A
  • Found everywhere else
  • thinner epidermis than thick skin
  • Hair follicles are widespread except for a few locations
30
Q

Summarize the epidermis

A

Stratified squamous keratinized epithelium
5 layers
-stratum basale-can differentiate

  • stratum spinosum- maturing and slowly dying cells
  • stratum granulosum- cells that are about to die
  • stratum lucidum- thick skin only
  • stratum corneum- dead keratinized cells
31
Q

Describe stratum basale

A

Single layer of cuboidal to low columnar cells

  • mitotically active
    • keratinocytes stem cells (stratum germinativum )
  • Merkel cells
  • melanocytes
  • noticeable basophilia on H&E staining
32
Q

Describe stratum basale staining

A

Small cells with scant basophilic staining cytoplasm

  • nuclei closely spaced
  • contains many melanin granules
  • synthesize keratin filaments
33
Q

Where are stratum basale connected to and located?

A

Rests on the basal lamina
Attached by hemidesmosomes

Extensive other anchoring cell junctions
Desmosomes

Clinical correlations: bullous pemphigod

34
Q

Describe stratum spinosum

A

Several cell layers thick

Keratinocytes are larger than those in the stratum basale

Make cytokeratin/keratin filaments

Exhibit numerous cytoplasmic processes or spines

  • Prickle cell layer
  • Processes of neighboring cells are connected to each other via desmosomes
    • Appears as a slight thickening and is known as node Bizzozero
35
Q

How do stratum spinosum cells change?

A

Gradually change their appearance as they move closer to the surface
-Increase in size and become flattened in a plane parallel to the surface

36
Q

What are the noticeable cells of the stratum spinosum?

A

-most noticeable in the most superficial layer of cells- nuclei become elongated instead of ovoid

  • Keratinocytes in uppermost part of this layer
    • begin to produce keratohyalin granules
    • lamellar bodies
  • Langerhans cells
    • Also found predominantly in this layer, but are able to move freely throughout epidermis

Clinical correlation: pemphigus vulgaris

37
Q

Describe stratum granuosum

A

Most superficial of the no keratinized cells

Averages 1-3 cell layers thick

Contains conspicuous granules which give them a granulated appearance

  • keratohyalin granules
    • Irregular shaped, variably sized, stains intensely basophilic
    • Cystine and histidine rich proteins= precursors for fillagrin
      • Responsible for aggregating the keratin filaments within the cornfied cells
38
Q

What are the keratinocytes of the stratum granulosum?

A

Keratinization (soft keratin)
-loss of organelles, thickened cell membrane, decreased pH

Lamellar bodies
-epidermal water barrier

Musculoskeletal System (41 decks)

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