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Histology > Integumentary > Flashcards

Integumentary Flashcards

0
Q

Functions of skin:

A
  1. Barrier - protects body against physical, chemical, and biological agents
  2. Immunologic function - antigen processing, provides information to appropriate effector cells in lymphatic tissue
  3. Homeostasis - Regulation body temp and water loss
  4. Sensory - conveys sensory info about external environment
  5. Endocrine - secretes hormones, cytokines, and growth factors, converts 7-dehydrocholesterol into vitamin D precursor
  6. Excretory function - exocrine secretion of sweat, sebaceous, and apocrine
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1
Q

Epidermal derivatives of skin:

A

Hair and hair follicles, sweat glands, sebaceous glands, and nails

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2
Q

Three layers of the skin:

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

Epidermis:

A

Outermost layer; epithelum exposed to external environment

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4
Q

Dermis:

A

Layer of dense CT beneath the dermis - mechanical support and strength to skin

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5
Q

Hypodermis:

A

Subcutaneous tissue, lies deep to dermis and contains varying amounts of adipose tissue

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6
Q

Two types of epidermis:

A
  1. Thick skin - found on palms and soles

2. Thin skin

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7
Q

Thick skin has a thick epidermis mainly due to thick:

A

Stratum corneum

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8
Q

Two key features of thick skin:

A

No hair/hair follicle and no sebaceous glands

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9
Q

Thin skin has a thin ______ and contains _____ and ________.

A

Epidermis; hair and sebaceous glands

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10
Q

Layers of epidermis:

A
  1. Stratum basale
  2. Stratum spinosum
  3. Stratum granulosum
  4. Stratum lucidum
  5. Stratum corneum
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11
Q

Stratum basale (germinativum) has a single layer of small cuboidal to low columnar cells resting on the _________.

A

Basal lamina (at the basal surface of the epithelium)

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12
Q

Stratum basal contains mitotically ____ cells that give rise to _________.

A

Active; keratinocytes

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13
Q

Basal cells have closely spaced nuclei with a ________ cytoplasm.

A

Basophilic

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14
Q

Cells are attached to each other and keratinocytes by ______ and are anchored to the basal lamina by __________.

A

Desmosomes; hemidesmosomes

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15
Q

After mitosis, the keratinocytes move up into the __________.

A

Stratum spinosum

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16
Q

Stratum spinosum is composed primarily of ______.

A

Keratinocytes - producing keratin

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17
Q

Stratum spinosum cells exhibit numerous cytoplasmic processes connected to processes from adjacent cells by __________.

A

Desmosomes

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18
Q

Prickle cell layer:

A

Cell shrinkage during fixation results in increase in intercellular space and the appearance of spines or prickles (in stratum spinosum)

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19
Q

Cells _____ in size as they mature and move toward the surface.

A

Increase

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20
Q

Stratum granulosum is the most superficial ________ layer of the epidermis.

A

Nonkeratinized

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21
Q

SG cells contain numerous _________ granules.

A

Keratohyalin (intensely basophilic)

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22
Q

Keratohyalin granules contain protein precursors of ____ and _____ which aggregate keratin filaments in stratum corneum.

A

Filaggrin; trichohyalin

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23
Q

Stratum lucidum is normally only seen well in _____ skin.

A

Thick

SL is the highly refractile, glassy layer containing eosinophilic cells in which keratinization is well advanced

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24
Q

Stratum corneum is the ______ layer of the epidermis.

A

Outermost; exposed to the external environment and contains flattened, desiccated, anucleate cells

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25
Q

Stratum corneum is where cells lose their ____ and _____ and become filled almost entirely with keratin filaments.

A

Nucleus; cytoplasmic organelles

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26
Q

Stratum corneum is the major constituent of:

A

Epidermal water barrier

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27
Q

______ accounts for most of the thickness of thick skin.

A

Stratum corneum

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28
Q

Layers of the dermis:

A
  1. Papillary layer

2. Reticular layer

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29
Q

Papillary layer is the more ______ layer of dermis and consists of _______ and threadlike elastic fibers.

A

Superficial; loose CT with type I and type III collagen

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30
Q

The ______ attach the epidermis to the dermis.

A

Dermal papillae - fingerlike dermal protrusions into the epidermis

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31
Q

Complementary epidermal protrusions that project into the papillary dermis are _______.

A

Epidermal ridges (these and dermal papillae are most prominent in thick skin of palms and soles)

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32
Q

Papillary layer contains blood vessels that supply nutrients but do not enter the ______.

A

Epidermis.

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33
Q

Reticular layer is made of _______ underlying the papillary layer.

A

Dense irregular CT

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34
Q

Reticular layer is characterized by thick, irregular bundles of _______ and coarse elastic fibers.

A

Type I collagen

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35
Q

Cells of Epidermis:

A
  1. Keratinocytes
  2. Melanocytes
  3. Langerhan’s cells
  4. Merkel cells
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36
Q

_____ are the predominant cell type in the epidermis.

A

Keratinocytes

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37
Q

Keratinocytes originate from mitosis of stem cells in the _______.

A

Stratum basale

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38
Q

Two functions of keratinocytes:

A
  1. Produce keratin - major structural component of epidermis

2. Formation of epidermal water barrier

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39
Q

Keratinocytes are held together by:

A

Desmosomes

40
Q

As keratinocytes move through stratum spinosum, they are continuously produced and become grouped into thick bundles called:

A

Tonofibrils (cells become more eosinophilic when tonofibrils take up more of the cytoplasm)

41
Q

In the upper part of the stratum spinosum, free ribosomes synthesize _____ which moves into the stratum granulosum.

A

Keratohyalin granules

42
Q

Intermediate filament-associated proteins, filaggrin and trichohyaline, are contained by ________ and promote aggregation of _______ into tonofibrils.

A

Keratohyalin granules; keratin filaments

43
Q

Conversion of granular cells into cornified cells:

A

Keratinization

44
Q

Epidermal water barrier in stratum corneum prevents ______ and maintains ________.

A

Water loss; body hemostasis

45
Q

Epidermal water barrier in SC - cell envelope:

A

Insoluble proteins on inner surface of plasma membrane - imparts strength

46
Q

Epidermal water barrier in SC - lipid envelope:

A

Layer of lipids extruded from lamellar bodies in stratum granulosum - imparts hydrophobicity

47
Q

________ are dendritic cells that are scattered among basal cells of the stratum basale.

A

Melanocytes

48
Q

Melanocytes are _____ in stratum basale and extend long processes between ______ of stratum spinosum.

A

Clear; keratinocytes

49
Q

Melanocytes do not form _______ with neighboring keratinocytes.

A

Desmosomal attachments

50
Q

Function of melanocytes:

A

Produce melanin, pigment that protects cells against damage from nonionizng ultraviolet irradiation

51
Q

Melanin is produced by oxidation _______ to _______ by tyrosinase.

A

Tyrosine; 3,4-dihydroxyphenylalanine

52
Q

Premelanosomes, the electron-opaque mature melanin granule, are near the ______, while melanosomes are near the end of the processes.

A

Golgi apparatus

53
Q

Melanosomes and the melanin within are transferred to ______ by pigment donation, which involves phagocytosis of tips of melanocyte processes by ______.

A

Keratinocytes

54
Q

Skin color is determined by:

A
  1. Melanin content - degradation of melanin more rapid in individuals with light skin
  2. Two genetically determined forms of melanin - eumelanin (brown-black) and pheomelanin (red-yellow)
55
Q

Langerhan’s cells process ______ entering thru the skin.

A

Antigens

56
Q

Langerhan’s cells reside primarily in the:

A

Stratum spinosum

57
Q

Function of Langerhan’s cells:

A

Ingests antigens by phagocytosis after they bind to cell surface receptors, leave epidermis and travel to regional lymph node via lymphatics. In the lymph node, they become dendritic cells, which when activated stimulate T cells

58
Q

_______ are modified epidermal cells located in the _______ that function in cutaneous sensation.

A

Merkel’s cells; stratum basale (most abundant in fingertips)

59
Q

Merkel’s cells are closely associated with expanded terminal bulb of afferent _________.

A

Myelinated nerve fibers(combination of neuron and epidermal cell = Merkel’s corpuscle)

60
Q

A hair follicle is an invagination of the _____ and extends deep into the _______.

A

Epidermis; hypodermis

61
Q

Hair follicles are associated with ______ glands and are found only in ____ skin.

A

Sebaceous glands; thin

62
Q

Base of the hair follicle (bulb) is invaginated by vascularized _________, the dermal papilla.

A

Loose CT

63
Q

Dermal papilla is surrounded by:

A

Matrix cells - germinative layer of the follicle and are responsible for hair growth (this layer also contains melanocytes)

64
Q

Dividing matrix cells in the germinative layer differentiate into __________ cells and the _____ root sheath (of hair follicle).

A

Keratin-producing; internal

65
Q

Layers of the hair follicle:

A
  1. Internal root sheath
  2. External (outer) root sheath
  3. Connective tissue sheath
66
Q

__________ contains cells with soft keratin formed from the germinative layer of bulb and is broken down at the level of sebaceous gland.

A

Internal root sheath

67
Q

Part of epidermis that extends the entire length of follicle:

A

External (outer) root sheath

68
Q

Arrector pili muscles are attached to the _______ sheath.

A

Connective tissue sheath

69
Q

Functions of arrector pili muscle:

A
  1. Contraction responsible for goosebumps

2. Contraction aids sebaceous gland secretion

70
Q

Hair has 2 or 3 concentric zones of keratinized cells:

A
  1. Cuticle - outermost layer
  2. Cortex - middle layer in thick hair or inner layer in thin hair
  3. Medulla - inner most layer, present in THICK HAIR ONLY
71
Q

Formation of hair: cells divide in the germinative layer of the _____ in the bulb of the hair follicle. Cells from the apex of the papilla give rise to the ______ of the hair.

A

Matrix; medulla

72
Q

Basal stem cells produce cells of the hair ____ and ____.

A

Cuticle and cortex

73
Q

Hair cells contain ____ keratin, while cells of the epidermis and internal root sheath contain ____ keratin.

A

Hard; soft

74
Q

______ consists of densely packed keratin filaments embedded in a matrix of keratin with a high ______ content.

A

Hard keratin; sulfur - responsible for hardness

75
Q

Unlike soft keratin, the formation of hard keratin does not involve _________ and it does not _______.

A

Keratohyalin granules; desquamate

76
Q

_______ sweat glands are distributed over the entire body surface except for lips and part of external genitalia (found in both thin and thick skin).

A

Eccrine sweat glands

77
Q

Eccrine sweat glands are classified as ________.

A

Simple, coiled tubular gland
Secretory unit - epithelium is pseudostratified cuboidal or columnar
Duct unit - epithelium is stratified cuboidal

78
Q

Functions of eccrine sweat glands:

A

Temperature regulation - sweat evaporates and cools skin. Eccrine glands respond to heat (thermoregulatory sweating) and stress (emotional sweating) - controlled by sympathetic portion of ANS

79
Q

Three cell types in secretory segment of Eccrine sweat glands:

A
  1. Clear cells - abundant glycogen
  2. Dark cells - abundant rER and secretory granules
  3. Myoepithelial cells - cytoplasm has actin filaments
80
Q

Clear cells:

A

Abundant glycogen, produce the watery component of sweat

81
Q

Dark cells:

A

Abundant rER and secretory granules, produce proteinaceous component of sweat

82
Q

Myoepithelial cells:

A

Contractile cells that lie between the secretory cells and basal lamina, contraction of these cells results in rapid expulsion of sweat from gland

83
Q

______ sweat glands are limited to axilla, areola, and nipple of mammary gland, skin around anus, and external genitalia.

A

Apocrine - development is dependent on sex hormones and become functional at puberty

84
Q

Apocrine sweat glands are classified as:

A

Simple coiled tubular glands and may be branched
Secretory unit: coiled tubular with wide lumen located deep in dermis and upper hypodermis, epithelium is simple cuboidal or columnar, secretion containing pheromones
Duct portion: narrow lumen, epithelium is stratified cuboidal

85
Q

Apocrine sweat glands empty into _____.

A

Hair folllicle

86
Q

Unlike the eccrine sweat gland, no resorption occurs in the ____ segment.

A

Duct - product is not altered in duct

87
Q

Function of apocrine sweat glands:

A

Release pheromones - important in sexual, maternal, and social behaviors in animals
Respond to emotional and sensory stimuli, but not heat - symphathetic control

88
Q

Secretory cells of apocrine sweat glands contain:

A

Secretory granules and numerous mitochondria

89
Q

______ are distributed in thin skin over the entire body surface and are classified as ________.

A

Sebaceous glands; simple saccular or acinar gland

90
Q

The short duct of the sebaceous gland is lined by _______ continuous with the _____ root sheath.

A

Stratified squamous epithelium; external root sheath

91
Q

Sebaceous and _____ develop as an outgrowth of the ______ root sheath of the hair follicle.

A

Hair follicle; external

92
Q

Secretory cells of sebaceous glands produce an oily product called ____, which is released via a _____ method.

A

Sebum; holocrine

93
Q

There are no ______ cells in sebaceous glands.

A

Myoepithelial cells

94
Q

Function of sebum:

A

Not clearly defined - may be bacteriostatic, have a barrier function or have a pheromone function, development of acne

95
Q

Free nerve endings:

A

Neuronal processes in the epidermis or dermis that lack a CT or Schwann cell investment, most numerous neuronal receptors in epidermis - function in sensing fine touch, heat, cold, and other sensations. In the dermis, they can attach to the outer root sheath and surround hair follicles

96
Q

Meissner’s corpuscle (encapsulated nerve endings):

A

Found in dermal papilla of papillary layer of hairless skin - lips and palmar surfaces, function - touch receptors responsive to low frequency stimuli

97
Q

Pacinian corpuscle (encapsulated nerve endings):

A

Large, ovoid structures found in deeper dermis and hypodermis (fingertipes), composed of a myelinated nerve ending surrounded by a capsule (onion shaped), function - deep pressure sensors for mechanical and vibratory pressure, respond thru a displacement of the capsule lamellae –> depolarization of the axon

Histology (24 decks)

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