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MEDL 310 > Module 2: Skin > Flashcards

Module 2: Skin Flashcards

1
Q

4 major functions of skin

A

Protection
Sensation
Thermoregulation
Metabolic functions

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2
Q

Protection

A

against UV lights, mechanical, chemical, thermal damage
Prevent excess water uptake/loss
Physical barrier to invasion by microbes

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3
Q

Sensation

A

Largest sensory organ in the body

Receptors for touch, pain, pressure, temp

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4
Q

Thermoregulation

A

Major organ of thermoregulation
Body is insulated against heat loss by presence of hairs and subcutaneous fat tissue
Heat loss is through evaporation of sweat from skin surface and increased blood flow to dermis

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5
Q

Metabolic functions

A

subcutaneous adipose makes just major store of energy (used in synthesis of Vit D; synthesized from ergosterol, a derivative of cholesterol and requires exposure of skin to UV light)

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6
Q

3 layers of skin

A

Epidermis
Dermis
Subcutis or Hypodermis

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7
Q

Thick/thin skin refers to the thickness of

A

the epidermal layer

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8
Q

Thick skin

A

in areas with large amounts of abrasion
Palms of hands, soles of feet
Characterized by prominent granular layer and an increase in amount of keratin in outer layer of epidermis

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9
Q

Thin skin

A

covers remaining body surface
Smaller amount of keratin
Basically same structure as thick skin

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10
Q

Furrow

A

“dip” that separates narrow epidermal ridges
In both thick and thin skin

Epidermal/dermal layer has regular arrangement of ridges (adds to skins ability to resist abrasion and friction)
Fingerprints

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11
Q

Interpapillary peg

A

AKA Rete ridges

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12
Q

Dermal ridges

PICTURE*****

A

Primary dermal ridge mirrors primary epidermal ridge and are divided into 2 secondary ridges by interpapillary pegs of epidermis

Pegs are most prominent in soles and palms

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13
Q

Epidermis layers (Bottom to surface)

A 
Stratum Basal
Stratum Spinosum
Stratum Granulosum
Stratum Lucidum (Only in thick skin)
Stratum Corneum
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14
Q

What classification is skin

A

stratified squamous keratinizing epithelia

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15
Q

Epidermis

A 
epithelium layer
Waterproof, bacteria and wear resistant
Cells constantly being replaced
Most cells are keratinocytes
Undergo gradual transformation into scales of keratin as they become displaced from the basal layer below (4wks in healthy individual)
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16
Q

Stratum Basal

A

AKA Germinal or Basal Layer

Low columnar
Form single layer separated from the dermis by a basement membrane
Evidence of mitosis is occasionally present

Hemidesmosomes provide anchor between basement membrane and the cells of basal layer

17
Q

Desmosomes

A

cells between basal and spinosum layer to provide attachment holding the two layers together

18
Q

Stratum Spinosum

A

AKA Spinosum or Prickle cell layer

Layer is several cells thick; polyhedral in shape
Cells appear to have elongated spines joining the cells (are actually artifact/broken desmosomes due to shrinkage during tissue processing)
Tonofibrils present between cells that give tensile strength

19
Q

Stratum Granulosum

A

AKA Granular Layer

A few cells thick
Flattened cells filled with granules (involved in production of keratin)
Outer cells of layer die, losing nucleus and cytoplasm and produce a layer of keratin (released upon death)

20
Q

Stratum Lucidum

A

AKA Lucidum Layer

Only present in thick skin In between granular and cornified layers

Cells are essentially a cell membrane containing keratin

21
Q

Stratum Corneum

A

AKA Corneum or Cornified Layer

Layer of keratin formed from flattened fused cells without any organelles or nuclei

22
Q

3 other cells in epidermis

A

Melanocytes
Langerhans
Merkel

23
Q

Melanocytes

A

produce melanin granules from tyrosine in presence of tyrosinase
Between keratinocytes of stratum basal
Granules produced are transferred to keratinocytes
Function of melanin is to be protection from UV light

24
Q

What is a mole the result of

A

benign accumulation of melanocytes

Malignant melanoma is a malignant tumor of melanocytes

25
Langerhans cells
lie in stratun spinosum Antigen presenting cells (part of immune system) When stimulated, migrate to regional lymph nodes and present antigen to T lymphocytes
26
Merkel cells
sensory receptors for touch | Located in stratum basal
27
Summary of Layers of Epidermis
BOTTOM Stratum Basal: Single layer, cuboidal or low columnar, mitosis, hemidesmosomes attach to basement membrane, desmososmes attach to each other, melanocytes found between keratinocytes, Merkel cells sparsely scattered Stratum Spinosum: Several layers, polyhedral, artifact gaps with filaments, desmosome attached, Langerhans cells prominent Stratum Granulosum: Few layers, flattened cells, basophilic granules of keratinohyaline Stratum Lucidum: Barely distinguishable, flattened cells (mostly cell membrane), translucent cytoplasm, nuclei undergoing karylolysis, thick skin only Stratum Corneum: Compact layer of soft keratin, flat scales, anucleate, desmosome attachment, waterproof OUTER SURFACE
28
Basement Membrane
separates epidermis from dermis
29
2 Layers of dermis
Papillary dermis: Adjacent to epidermis, thin layer of delicate fibrocollagenous support tissue with many fine branched elastic fibers and reticular fibers, blood vessels, sensory nerve endings Reticular dermis: Forms bulk of dermis, denser than papillary, contains fibrocollagenous tissue with many elastic fibers and cells (fibroblasts, macrophages, occasional fat cells, nerve endings, arterioles, capillaries, venules, lymphatics and skin appendages throughout)
30
Hypodermis or Subcutis
Rich vascular network that branches into dermis Lymphatics and nerves present Lots of adipose tissue Downward extensions of collagen or septae (from dermis) attaches the skin to the deep fascia, muscles and bone
31
Hair follciles
tubular epithelial structure opening onto the epidermis External root sheath is modified epidermis Base is a hair bulb where cells proliferate to form hair shaft and internal root sheath Associated with arrector pili muscle (attaches to connective tissue surrounding hair sheath; allows hair to stand erect; not in thick skin) and sebaceous glands
32
Sebaceous Glands
holocrine, simple, branches acinar glands Flask shaped, stain pale outgrowth of external root sheath of hair follicle Composed of cell cluster with polyhedral cells in center, and cuboidal around edges Produce an oily substance, sebum, which coats hair and thin skin surface
33
Eccrine (merocrine) sweat glands
simple coiled tubular glands Ducts are stratified cuboidal epi Secretory portion is large cuboidal or simple columnar epi with associated myoepithelial cells (responsible for expulsion of sweat into excretory ducts) Glands originate in dermis and rise through epidermis to skin surface Numerous in thick skin
34
Apocrine Sweat glands
become prominent and functional after puberty Areolae of breast, axillae, genital regions Produce a slightly milky secretion with some loss of fragments of the cell in response to external stimuli Secretory portion has large lumen line with simple cuboidal epi Duct is similar to eccrine glands Ducts open into hair follicles
35
Nails
highly specialized dense keratinized plate which sits on nail bed made of stratified squamous epi Nail root is at proximal end of nail plate and extends deep into dermis (attached to periosteum of distal phalanx) nail growth occurs through differentiation and proliferation of epi under the nail root Nail plate slides along nail bed as it grows

MEDL 310 (29 decks)

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