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Dermatology - Chapters > Chapter 2 Outline: Structure and Function of Skin > Flashcards

Chapter 2 Outline: Structure and Function of Skin Flashcards

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1
Q

Skin disease is divided into _______

A

growths and rashes

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2
Q

a neoplastic change in the skin

A

growth

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3
Q

an inflammatory reaction in the skin

A

rash

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4
Q

what are growths divided into

A

epidermal, pigmented, and dermal proliferative processes

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5
Q

Rashes are divided into

A

with and those without an epidermal component

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6
Q

major function is to act as a barrier against an inhospitable environment- to protect the body from the influences of the outside worth

A

skin

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7
Q

the major barrier of the skin is

A

epidermis

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8
Q

contains blood vessels, nerves, and appandeages

A

dermis

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9
Q

the third deepest layer of the skin is the

A

subcutaneous fat

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10
Q

what is the principal cell in the epidermis

A

keratinocytes

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11
Q

what are the layers of the epidermis is ascending order

A

basal cell
stratum spinosum
stratum granulosum
stratum corneum

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12
Q

undifferentiated , proliferating cells

A

basal cells

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13
Q

contins keratinocytes connected by desmosomes

A

stratum spinosum

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14
Q

what kind of granules are seen in seen in the stratum granulosum

A

keratohyalin granules

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15
Q

major physical barrier of the epidermis

A

stratum corneum

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16
Q

what determines skin color

A

number and size of melanosomes, not melanocytes

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17
Q

derived from bone marrow and are the skins first line of immunologic defense

A

langerhans cells

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18
Q

substrate for attachment of the epidermis to the dermis

A

basement membrane zone

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19
Q

what are the four major ultrastructural regions of the epidermis

A
  1. hemidesmosomal plaque of the basal keratinocyte
  2. lamina lucida
  3. lamina densa
  4. anchoring fibrils located in the sub lamina dense region of the papillary dermis
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20
Q

T/F In normal skin, cell division does not take place above the basal cell layer.

A

true

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21
Q

How long does it take for cells to be shed?

A

4 weeks…2 weeks = from basal to granular & 2 weeks = cells to cross the stratum corneum

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22
Q

_____ and _____ increases the rate of proliferation and maturation

A

injury and inflammation

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23
Q

what differentiate from the basal cells and produce keratin?

A

keratinocytes

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24
Q

where are keratinocytes located?

A

stratum spinosum

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25
Q

fibrous protein that is a major component of the horny stratum corneum

A

keratin produced from keratinocytes

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26
Q

where does the stratum spinosum derive its name from?

A

spines or intercellular bridges that extend between keratinocytes and are visible with light microscopy

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27
Q

Ultrastructurally what are the “spines” or intercellular bridges in the stratum spinosum composed of?

A

desmosomes

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28
Q

extensions of keratin within the keratinocyte, functionally they hold cells together

A

desmosomes

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29
Q

an autoimmune disorder characterized by thickened epidermis and increased scale? associated with what cell layer?

A

psoriasis- basal cell layer

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30
Q

autoimmune blistering disease wherein antibodies directed against desmosomes result in keratinocyte separation?.

A

pemphigus vulgaris - stratum spinosum

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31
Q

where do cells acquire additional keratin and become more flattened

A

stratum granulosum

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32
Q

also in the stratum granulosum cells contain distinctive dark granules, seen easily on light microscopy composed of __________

A

keratohyalin

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33
Q

What two proteins does keratohyalin contain?

A

profilaggrin and involucrin

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34
Q

precursor to filaggrin

A

profilaggrin

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35
Q

plays an important role in the aggregation of keratin filaments int he stratum corneum

A

profilaggrin

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36
Q

plays a role in formation of the cell envelope of cells in the stratum corneum

A

involucrin

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37
Q

an inherited dry skin condition secondary to deficient filaggrin production

A

Ichthyosis vulgaris (as noted on light microscopy of a skin biopsy by a reduced or absent granular layer of epidermis

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38
Q

granular cells also contain ______, which are visualized with electron microscopy.

A

lamellar granules

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39
Q

contains polysaccharides, glycoproteins, and lipids that extrude into the intercellular space and ultimately are thought to help form the cement that holds together the stratum corneum cells

A

lamellar granules

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40
Q

responsible for the eventual destruction of cell nuclei and intracytoplasmic organelles - stratum granulosum

A

degradative enzymes

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41
Q

____ cells contain keratohyalin and lamellar granules

A

granular cells

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42
Q

latter containing cells that are large, flat, polyhedral, platelike envelopes filled with keratin

A

stratum corneum

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43
Q

a semi-impenetrable layer that constitutes the major physical barrier of the skin

A

stratum corneum

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44
Q

dendritic pigment producing cells located in the basal cell layer

A

melanocytes

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45
Q

the dendrites of melanocytes extend into where? to serve as what?

A

extend into the stratum spinosum - and serve as conduits

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46
Q

conduits

A

pigment granules are transferred to their neighboring keratinocytes

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47
Q

The pigment granules are termed ______

A

melanosomes

48
Q

pigment within the granules is termed

A

melanin

49
Q

what are preferentially situated above the nucleus to protect the DNA

A

melanosomes

50
Q

what stimulates the melanocytes to increase pigment production and disperse their melanosomes more widely

A

sunlight

51
Q

melanosomes in _________ are larger in size and more numerous compared with melanosomes in ________.

A

dark skin compared to light skin

52
Q

the difference in skin pigmentation depends on what?

A
  1. number and size of melanosomes

2. dispersion in the skin

53
Q

dendritic cells in the epidermis that have an immunologic function; derived from bone marrow and constitute about 5% of the cells within the epidermis

A

langerhan cells

54
Q

tennis racket shaped granules in stratum spinosum

A

langerhan cells

55
Q

identical to tissue macrophages and present antigens to lymphocytes, with which they interact through specific surface receptors.

A

langerhan cells

56
Q

located in the basal cell layer, more numerous on the palms and soles and are connected to keratinocytes

A

merkel cells

57
Q

function as mechanoreceptors

A

merkel cells

58
Q

a rare skin cancer high mortality rate associated with merkel cells

A

merkel cell carcinoma

59
Q

what is the dermal epidermal junction - interface between the epidermis and dermis

A

basement membrane zone

60
Q

provides structural integrity and is biologically active

A

dermis

61
Q

what are the primary components of dermis

A

collagen, elastin, and extrafibrillar matrix

62
Q

principal component of the dermis and represents 70% of skins dry weight

A

collagen

63
Q

the two fibrous proteins in the dermis that form the strong, yet compliant skeletal matrix

A

collagen and elastin

64
Q

what is the uppermost part of the upper dermis

A

papillary dermis

65
Q

collagen fibers are fine and loosely arranged in what part of the dermis

A

uppermost part (papillary dermis)

66
Q

collagen fibers are thick and densely packed where in the dermis?

A

reticular dermis

67
Q

where are elastin fibers primarily located; they are thinner and more loosely arranged than collagen fibers

A

reticular dermis

68
Q

what fills the space between fibers

A

extrafibrillar matrix

69
Q

a nonfibrous material made up of several several different mucopolysaccaride molecules? collectively called _____ & _____

A

extrafibrillar matrix

  1. proteoglycans
  2. glycosaminoglycans
70
Q

what imparts to the dermis a more liquid quality which facilities movement of fluids, molecules, and inflammatory cells

A

extrafibrillar matrix

71
Q

What are the most important sensory receptors of the skin and where are they found?

A

Free nerve endings, in the dermis; nerve supply of the skin is segments (dermatomal) with considerable over lab between segments.

72
Q

What two functions do blood supply of the skin serve? Where are the blood vessels found?

A

in the dermis

  1. nutrition
  2. temp regulation
73
Q

What does the epidermis depend on for nutrients and oxygen? Why?

A

Epidermis has no intrinsic blood supply and therefore depends on the diffusion of nutrients and oxygen from vessels in the papillary dermis.

74
Q

What is the vasculature of the skin arranged in?

A

Two horizontal plexuses.

  1. Superficial
  2. Deep
75
Q

Located at the lower border of the papillary dermis

A

superficial vascular plexus

76
Q

located in the reticular dermis

A

deep plexus

77
Q

What is achieved through shunts between the plexuses of the skin? How?

A

Temperature Regulation
Heat Loss = increased blood flow in the superficial plexus
Heat Gain = shunting of blood to the deep plexus conserves heat

78
Q

The skin appendages are derived from where?

A

Epidermis, but except for the nails are located in the dermis

79
Q

What are the skin appendages

A
  1. Eccrine & Apocrine sweat glands
  2. Hair follicles
  3. Sebaceous glands
  4. nails
80
Q

How are Eccrine glands activated?

A

emotional and thermal stimuli

81
Q

What can be used to treat axillary hyperhidrosis by blocking acetylcholine action?

A

Botox - Botulinum toxin type A

82
Q

What is the function of the Eccrine sweat gland?

A

thermal regulation

83
Q

What is the total secretory capacity of Eccrine sweat glands per day?

A

10L

84
Q

Eccrine Sweat secreted in the glandular portion is _____ to plasma but becomes _____ by the time it exits the skin as a result of ductal reabsorption of electrolytes.

A

isotonic; hypotonic

***glandular excretion is followed by ductal absorption

85
Q

The eccrine sweat glands are physiologically the most important skin appendage to who?

A
  1. physically active individuals

2. ppl living in hot climates

86
Q

Appocrine sweat glands are ______ dependent. They serve no useful function.

A

androgen

87
Q

What are apocrine glands responsible for? How?

A

Body Odor - action of bacteria on excrete apocrine sweat

88
Q

Unlike in eccrine glands, in which the secretory cells remain intact, in apocrine glands, the secretory cells _____ their luminal (apical) portions as part of the secretory product.

A

decapitate

89
Q

Where is the sweat from the apocrine gland drained into?

A

hair follice

90
Q

What are the two sizes of hair?

A

vellus hairs - short, fine, light colored & barely noticed

terminal hairs - thicker, longer, and darker than the vellus type

91
Q

How are terminil hairs influenced?

A

homones - appear at puberty

92
Q

T/F The cells in the hair bulb replicate faster than the normal epidermal basal cells; these cells constitute the cell matrix.

A

true

93
Q

What in the matrix contributes pigment?

A

melanocytes

94
Q

As the matrix cells continue to divide what happens to the hair?

A

it is pushed outward and exits through the epidermis at a rate of about 1 cm per month.

95
Q

Hair growth in an individual follicle is cyclic, which growth in what phases?

A

anagen
catagen - transitional
telogen - resting

96
Q

How much hair is shed per day? How is this normal shedding rate kept constant?

A

25-100 hairs per day - because at any time 80-90% of scalp hair is in the anagen phase and 10-20% is in the telogen phase

97
Q

How is the hair sitting in the dermis at rest? What causes it to change?

A

at an angle; when the arrector pili muscle contracts the hair is in vertical position

98
Q

What do sebaceous glands produce?

A

oily substance- sebum
*which has no known function ; in fact the skin of children and the palms and plantar skin of adults function well without sebum.

99
Q

Where are sebaceous glands found?

A

where ever hair follicles are found

100
Q

Ectopic sebaceous glands are often found on mucous membranes where they may form small yellow papules called what?

A

Fordyce spots

101
Q

Sebaceous glands are under what type of control?

A

androgen

102
Q

When are sebaceous glands enlarged?

A

New borns - b/c of maternal hormones

preadolescence - stimulation by adrenal androgens to reach full size puberty, when gonadal androgens are produced

103
Q

What in sebaceous glands are wholly secreted to form sebum. (halocrine secretion)

A

Lipid-Laden Cells

104
Q

The majority of the lipid found in sebaceous gland cells is composed of what?

A

Triglycerides

105
Q

made of keratin, which is formed from a matrix of dividing epidermal cells; hard and flat and lie parallel to the skin surface

A

nails

106
Q

hard translucent structure composed of keratin; ranges in thickness from 0.2 to 0.65

A

nail plate

107
Q

what epithelial zone of the nail helps to protect the matrix? how?

A

proximal nail fold - the stratum corneum produced there forms the cuticle

108
Q

what epithelial zone of the nail produces the nail plate from its rapidly dividing, keratinizing cells?

A

matrix

109
Q

what epithelial zone of the nail produces a minimal amount of keratin which becomes tightly adherent to the bottom of the nail plate?

A

nail bed

110
Q

what causes the pink color of the nail?

A

the vascularity in the dermis of the nail bed

111
Q

what epithelial zone of the nail underlies the free distal edge of the nail plate.

A

hyponychium

112
Q

what seals the junction of the distal nail bed and nail plate?

A

stratum corneum produced “there” ? forms a cuticle to seal the junction of the distal nail bed and plate.

113
Q

What lies between the dermis and the underlying fascia?

A

subcutaneous fat

114
Q

what is the function of the subcutaneous fat?

A
  1. helps to insulate the body from cold
  2. cushions deep tissues from blunt trauma
  3. serves as a reserve source of energy for the body
115
Q

aggregates of fat cells called ______, are separated by fibrous septa that are traversed by blood vessels and nerves where?

A

subcutaneous fat layer

116
Q

Biologically active fat cells play a role in _______ as evidence by metabolic disturbances in obese children and adolescents with peripheral insulin resistance.

A

hormone messaging

Dermatology - Chapters (18 decks)

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