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Histology > Skin System > Flashcards

Skin System Flashcards

1
Q

Approximately how much of total body weight does skin comprise?

A

15 to 20%

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2
Q

What are some functions of skin?

A

(1) Protection against external threats (2) Provision of moisture control (3) Protection against UV radiation (4) Metabolism (synthesis of D3) (5) Thermoregulation (sweating, body hair, adipose) (6) Sensation

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3
Q

What is produced in the skin in response to UV exposure?

A

Melanin

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4
Q

The skin is composed of the ______________, an epithelial layer of ectodermal origin, and the _____________, a layer of mesodermal connective tissue

A
  1. Epidermis
  2. Dermis
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5
Q

At the irregular junction between the dermis and epidermis, projections called ________ ______________ interdigitate with invaginating ________ ____________ to strengthen adhesion of the two layers

A

Dermal papillae

Epidermal ridges

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6
Q

Beneath the dermis lies the _________________ tissue or ______________, a loose connective tissue layer that usually contains pads of adipocytes

A

Subcutaneous

Hypodermis

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7
Q

What type of tissue is skin primarily composed of?

A

Stratified squamous keratinized epithelium

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8
Q

What does the stratified squamous keratinized epithelium of skin primarily consist of?

A

Keratinocytes

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9
Q

Other than keratinocytes, what are three other epidermal cell types?

A

(1) Melanocytes, which produce pigments
(2) Langerhans cells, which present antigens
(3) Merkel cells, which provide tactile sensation

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10
Q

The epidermis forms the major distinction between thick skin found on the ___________ and ___________ and thin skin found elsewhere on the body

A

Palms

Soles

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11
Q

To what do the designations thick and thin refer?

A

The thickness of the epidermal layer

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12
Q

How many layers of keratinocytes are found in thin skin?

A

Four

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13
Q

How many layers of keratinocytes are found in thick skin?

A

Five

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14
Q

The _________________ layer or ____________ ______________ is a single layer of basophilic cuboidal or columnar cells on the basement membrane at the dermal-epidermal junction; it proliferates continuously with repeated mitotic divisions, where cells move upwards as they mature

A

Basal layer

Stratum basale

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15
Q

The _______________ layer or ________________ ________________ is normally the thickest epidermal layer and generally consists of polyhedral cells with central nuclei and nucleoli and active cytoplasm (producing keratins)

A

Spinous layer

Stratum spinosum

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16
Q

Which layer of the epidermis is also known as the prickle cell layer? What causes these prickles?

A

Spinous layer or stratum spinosum

Desmosomes

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17
Q

To what cytoskeletal elements do desmosomes connect?

A

Intermediate filaments

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18
Q

The ________________ layer or _____________ _________________ consists of three to five layers of flattened cells undergoing terminal differentiation of __________________; their cytoplasm is filled with intensely basophilic masses called ________________ _______________

A

Granular layer

Stratum granulosum

Keratinization

Keratohyaline granules

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19
Q

To what layer of epidermis do keratinocytes mature?

A

Granular layer

Stratum granulosum

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20
Q

Which epidermal layer is seen only in thick skin?

A

Stratum lucidum

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21
Q

Only found in thick skin, the stratum lucidum is a thin, translucent layer of extremely flattened ___________________ cells

A

Eosinophilic

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22
Q

The _______________ ________________ consists of 15 to 20 layers of flattened nonnucleated keratinized cells

A

Stratum corneum

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23
Q

What occurs to cells after they’ve undergone keratinization?

A

Lose their nuclei, fill their cytoplasm with filamentous keratins, and thicken their plasma membranes

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24
Q

Cornified cells are also called ________________

A

Squames

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25
Q

These cells are continously shed at the surface of the stratum corneum

A

Squames or nonnucleated keratinized cells

26
Q

The designations “thick” and “thin” refer to the thickness of the epidermal layer, which varies from ___ to ___ micrometers in thin skin and ___ to _____ micrometers in thick skin

A

75 to 150

400 to 1400

27
Q

What’s the order of epidermal layers from top to bottom?

A

Statum corneum

Stratum lucidum (thick skin only)

Stratum granulosum

Stratum spinosum

Stratum basale

28
Q

The color of the skin is the result of several factors, the most important of which are the keratinocytes’ content of _____________ and ________________ and the number of blood vessels in the dermis

A

Melanin

Carotene

29
Q

_____________ are brown or black pigments produced by the melanocyte, a specialized cell of the epidermis found among the cells of the ___________ layer and in hair follicles

A

Eumelanins

Basal layer

30
Q

_________________ is produced in red hair

A

Pheomelanin

31
Q

What are the histological features of melanocytes?

A

Pale staining, rounded cell bodies attached by hemisdesmosomes to the basal lamina, but lacking attachments to neighboring keratinocytes

Several long irregular cytoplasmic extensions from each melanocyte penetrate the epidermis, running between the cells of the basal and spinous layers

32
Q

Antigen-presenting dendritic cells of the epidermis are called _______________ cells and are most clearly seen in the spinous layer, representing between two and eight percent of epidermal cells

A

Langerhans cells

33
Q

______________ cells or epithelial tactile cells are sensitive mechanoreceptors essential for light tough sensation

A

Merkel cells

34
Q

The _________________ is the layer of connective tissue that supports the epidermis and binds it to the subcutaneous tissue

A

Dermis

35
Q

The thickness of the dermis varies according to the region of the body, but a ______________ _________________ is always found between the stratum basale of the epidermis and the _____________ layer of the dermis

A

Basement membrane

Papillary layer

36
Q

The thin _____________ ___________ of the dermis includes the dermal papillae and consists of loose connective tissue

A

Papillary layer

37
Q

Below the papillary layer is the ___________ ____________, which is much thicker and consists of dense irregular connective tissue with more fibers and fewer cells; a network of elastic fibers is also present

A

Reticular layer

38
Q

In the dermis, spaces between collagen and elastic fibers are filled with proteoglycans rich in _________________ ____________

A

Dermatan sulfate

39
Q

The ____________________ tissue refers to the loose connective tissue that binds the skin loosely to the subjacent organs, making it possible for the skin to slide over them

A

Subcutaneous

40
Q

What layer of tissue contains many fat cells and an extensive vascular suppy and is referred to as the hypodermis?

A

Subcutaneous tissue

41
Q

The connective tissue of the skin contains a rich network of blood and lymphatic vessels; the blood vessels that nourish the cells of the skin form two major plexuses. Where do these plexuses occur?

A
  1. Deep at the interface between the hypdermis and dermis
  2. Superficially between the papillary and reticular dermal layers
42
Q

___________ _________________ are elongated keratinized structures derived from invaginations of the epidermal epithelium

A

Hair follicles

43
Q

The growing hair follicle has a terminal dilation called the ____________ __________

A

Hair bulb

44
Q

A ______________ ____________ inserts into the base of the hair bulb and contains a capillary netwro required to maintain the hair follicle

A

Dermal papilla

45
Q

Epidermal cells covering the dermal papilla form the _____________ ___________ that produces and is continuous with the ____________ _____________

A

Hair root

Hair shaft

46
Q

_________________ are modifications of the epidermis that are composed of keratin and contain a free edge, body, and a root

A

Nails

47
Q

The proximal part of the nail is the ____________ ___________ and is covered by a fold of skin, from which the epidermal stratum corneum extends as the _______________

A

Nail root

Cuticle

48
Q

The _________ ___________ is bound to a bed of epidermis, the _________ ______, which contains only the basal and spinous epidermal layers

A

Nail plate

Nail bed

49
Q

The nail root forms from the __________ ____________ in which cells divide, move distally, and become keratinized

A

Nail matrix

50
Q

The crescent-shapped white area of the nail is called the ________________, which derives its color from the opaque nail matrix and immature nail plate below it

A

Lunula

51
Q

_____________ __________ are embedded in the dermis over most of the body

A

Sebaceous glands

52
Q

________________ is a complex mixture of lipids that are secreted from sebaceous glands; it is gradually moved to the surface of the skin along the hair follicle or duct

A

Sebum

53
Q

____________ ___________ develop as long epidermal invaginations embedded in the dermis and open to the skin surface or into hair follicle

A

Sweat glands

54
Q

What type of sweat gland is found widely distributed in the skin and is most numerous on the soles of the feet?

A

Eccrine sweat glands

55
Q

What type of sweat gland is confined to the axillary and perineal regions?

A

Apocrine sweat glands

56
Q

What is the most obious histological difference between eccrine and apocrine sweat glands?

A

Apocrine glands have much larger lumens

57
Q

The ______________ can be identified by its broad dermis and subcutaneous layers and abudant hair follicles

A

Scalp

58
Q

What part of the skin is characterized by the lack of hair and has developed structural modifications to resist shearing and frictional forces?

A

Soles

59
Q

What are some of the histological characteristics of soles?

A

A thick epidermis and prominent granular layer

A thick layer of keratin

Increased rete ridges to increase surface area

60
Q

Why do the soles have increase rete ridges?

A

To increase surface area of epidermis attached to the dermis

Histology (18 decks)

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