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Histo 1 > Integument > Flashcards

Integument Flashcards

1
Q

What is the integument function of the epidermis?

A
  • Protection
    • physical
    • chemical
    • pathogens
    • desiccation
    • UV
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2
Q

What is the integument function of vasculature?

A

Thermoregulation

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3
Q

What is the integument function of specialized nerve structures?

A

pressure and touch reception

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4
Q

What is the integument function of glands?

A

excretion

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5
Q

What is the integument function of cells that form the epidermis?

A

production of vitamin D

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6
Q

Basic Organization of Integument

A

Epidermis

Dermis

Associated Structures

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7
Q

Basic Organization of Integument: Epidermis

A

stratified squamous keratinized epithelium (regulated by cell death)

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8
Q

Basic Organization of Integument: Dermis

A

Loose CT (papillary)

Dense Irregular CT (reticular)

glands, nerves

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9
Q

Basic Organization of Integument: Associated Structures

A

hair

nails

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10
Q

What are the 5 layers of the epidermis from top to bottom?

A

stratum corneum

stratum lucidum

stratum granulosum

stratum spinosum

stratum basale

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11
Q

Resident Cell Types in the Epidermis

A

Keratinocytes → produce a lot of keratin

melanocytes → produce (not store) melanin (pigment)

Langerhans cells → APCs

Merkel’s Cells → visible on TEM as well, touch receptors → modified keratinocytes that form touch receptors

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12
Q

Define: Keratinocytes

A

Different stages of differentiation in different epidermal layers

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13
Q

Define: Stratum Basale

A

single layer of germ cells (basal cells)

cuboidal to columnar cells

mitotic figures

producing keratin

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14
Q

Define: Stratum Spinosum

A

Several layers

desmosomes - spiny appearance → maintain contact even if they shrink (spinal cells)

accumulate bundles of keratin filaments (tonofibrils)

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15
Q

What happens to cells in the stratum spinosum after mitosis?

A

One daughter cell remains in the stratum spinosum, the other stays in stratum basale.

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16
Q

Define: Stratum Granulosum

A

Keratohyalin (basophilic) granules associate with tonofibrils

lamellar bodies (lipid and enzyme filled vesicles) → sealant and penetration barrier between cells

start to lose other organells

nuclear fragmentation

(signs of cell death)

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17
Q

Define: Tonofibrils

A

bundles of keratin filaments

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18
Q

Major Morphological Features of Apoptosis

A
  • Cell flattens/condensation → terminal differentiation of keratinocytes
  • Nuclear condensation/fragmentation → terminal differentiation of keratinocytes
  • Membrane blebbing
  • Formation of apoptotic bodies → packaging of cell contents into vesicles
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19
Q

What is nuclear condensation/fragmentation visible with?

A

DAPI staining

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20
Q

What is membrane blebbing visible with?

A

light microscopy

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21
Q

Define: Stratum Corneum

A

flattened cell remnants containing aggregated tonofibrils with thickened plasma membrane

cells are desiccated and anucleated

a lot of lipids between them

cells can be sloughed off without damage to lower layers

can be thickened by friction

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22
Q

Water Barrier: Cell Envelope

A

thickened cell membrane due to insoluble proteins on the inner aspect

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23
Q

Water Barrier: Lipid Envelope

A

vesicles extruded from keratinocytes → derived from lamellar bodies

lipids (glycosphingo-, phospho-, ceramides)

lipases (acidic sphingomyelinase, sPLA2)

Proteases

more active at lower (more acidic) pH

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24
Q

What is the purpose of the water barrier?

A

prevents desiccation of underlying tissue

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25
Q

Define: Melanocytes

A

rounded cells with numerous projections that extend between keratinocytes through the stratum basale and the stratum spinosum

produce melanin → packaged into melanosomes and go to keratinocytes

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26
Q

Why does melanin go to keratinocytes?

A

it surrounds the nucleus of keratinocytes to protect from non-ionizing UV damage

prevents formation of cancer

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27
Q

How does the keratinocyte obtain the melanin?

A

keratinocyte eats the melanocyte and picks up melanosome

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28
Q

What is constant regardless of skin tone?

A

melanocyte/keratinocyte ratio is constant

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29
Q

What differs depending on skin tone?

A

melanosome size, number, and rate of degradation

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30
Q

Melanocyte/Keratinocyte Pigment donation process

A
  1. premelanosome
  2. melanosome
  3. melanosome inside a dendrite → melanosomes are transported along dendrites to adjacent keratinocytes of the stratum spinosum → melanin granules are internalized by adjacent keratinocytes → melanin granules form a nuclear protective shield against UV radiation
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31
Q

UV exposure alters:

A

Rate of melanin production through activity of tyrosinase → increases melanin production

chemical nature of melanin (appears darker) → increases protection

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32
Q

Define: Langerhans Cells

A

Dendritic antigen-presenting cells (MHCI and II)

No desmosomal contacts with keratinocytes

Involved in delayed-type hypersensitivity reactions (e.g. contact dermatitis)

Surveillance, dendritic, can initiate immune response

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33
Q

Define: Merkel’s Cells

A

touch receptors → abundant in most sensitive areas

modified epidermal cells → stratum basale

form desmosomes with keratinocytes and have keratin intermediate filaments

contain neurosecretory granules → can secrete neurotransmitters and activate nerves

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34
Q

Define: Merkel’s Corpuscle

A

mechanoreceptor → merkel’s cell and associated neuron

afferent myelinated nerve fibers lose their myelin sheath at the terminal and go through the basal lamina

Disk-like ending of nerve fiber is next to a Merkel’s cell

35
Q

Define: Thick Skin

A

palms and soles

sweat glands

hairless

no sebaceous glands → associated with hair follicles

36
Q

Define: thin skin

A

everywhere except palms and soles

hair (with sebaceous glands)
sweat glands present

dermis can be quite thick → depending on location

variable thickness (epi-dermis)

37
Q

How to differentiate thick vs thin skin?

A

look for → epidermal layers and hair

38
Q

Epidermal - Dermal Junction

A
  • Basal lamina connected to keratinocytes
  • interdigitations
  • dermal ridges
39
Q

How is the basal lamina connected to keratinocytes?

A

intermediate filaments by hemidesmosomes

microfilaments by focal adhesions

40
Q

Define: Rete Ridges

A

projections of epidermis

41
Q

Define: Dermal Papillae

A

projections of dermis

42
Q

Function of the Epidermal - Dermal Junction

A

increase surface area → attachment and nutrient exchange

much deeper ridges at sites of abrasion

43
Q

General Structure of the Dermis

A

loose CT next to epidermis

dense irregular beneath it

44
Q

Define: Dermis: Papillary Layer

A

Loose CT with → small blood vessels , nerves, lymphatics, meissner’s corpuscles

collagen types I and III

elastic fibers

45
Q

Define: Dermis: Reticular Layer

A

Between papillary layer and hypodermis

dense irregular CT with → larger nerves and blood vessels, hair follicles, pacinian corpuscles, ruffini end organs

46
Q

Define: Langer’s Lines

A

Regular Lines of Tension

Collagen and elastic fibers in the reticular layer are not oriented randomly

original lines were determined on cadavers

incisions made along these lines heal with less scarring

47
Q

Dermis: Vasculature

A

temperature regulation

arteriovenous anastomses shunt blood between two plexuses → subpapillary, cutaneous (reticular)

less blood flow = retain body heat → regulated by smooth muscle

48
Q

Define: Hypodermis

A

aka the Superficial Fascia

Loose CT and adipose tissue

anchors skin to underlying tissue

bases of sweat glands and hair follicles

49
Q

Integumentary glands

A

eccrine

apocrine

sebaceous

50
Q

Eccrine Gland

A

secretes sweat

simple duct

coiled tubular secretory

duct empties into surface of skin

located almost everywhere

51
Q

Apocrine Gland

A

dont secret by apocrine method

secrete sweat, pheromones

simple duct

coiled, tubular secretory

duct empties into hair follicle

located axilla, areola and nipple, anal region, external genitalia

52
Q

Sebaceous Gland

A

secretes by holocrine method

secretes lipids

branched duct

acinar (ball shaped) secretory

duct empties into hair follicle

located in hair and eyelid

53
Q

What is the reason you can quickly go from not sweating to sweating in sweat glands?

A

myoepithelial cells → contract to aid in sweat expulsion

surround the glandular cells

54
Q

What innervation do sweat glands have?

A

sympathetic autonomic

55
Q

Where are eccrine sweat glands not located?

A

in lips and external genitalia

56
Q

What type of secretion do eccrine sweat glands have?

A

water → secrete urea, water, salts, etc.

regulate body temp

57
Q

What are the differences between eccrine and apocrine glands?

A

apocrine glands are larger than eccrine with broader lumen

viscous secretion into the hair follicle

apocrine → short duct, large lumen

eccrine → long duct, smaller lumen

58
Q

Define: Nonencapsulated

A

free nerve endings in the epidermis

detect touch, pressure, heat, cold, pain

associated with hair follicles (mechanoreceptors)

can be associated with merkel cells

59
Q

Define: Encapsulated

A

ruffini ending (dermis)

meissner’s corpuscle (dermal papillae)

Pacinian Corpuscle (dermis and hypodermis)

60
Q

Define: Ruffini Ending

A

collagen based capsule

simplest encapsulated mechanoreceptor

touch and pressure (stretching)

groups of nerve terminals surrounded by a thin CT capsule (fluid-filled space)

axonal endings respond to displacement of collagen fibers

61
Q

Define: Meissner’s Corpuscle

A

found in hairless skin at the apex of the dermal papilla

endoneurial cells wrapped around a nerve terminal

unmyelinated ends of nerve fibers are spiral shaped

schwann cells from lamellae

light touch

62
Q

Define: Pacinian Corpuscle

A

deep pressure and vibrations

concentric layers of endoneurial cells around a myelinated nerve terminal

myelin is eventually lost

found in deepest layers of dermis and hypodermis

amplification of mechanical stimulus at edge

tree stump

63
Q

Hair Follicles

A

invagination of the epidermis → bulb is in the hypodermis or deep layers of the dermis

sheaths surround the growing shaft → internal root sheath, outer root sheath

hard keratin

arrector pili muscle → extend from follicle to papillary layer of the dermis

comprised of smooth muscle → lifts hair follicle when contracts/ helps you stay warm → goosebumps

64
Q

Hair Structure

A
  • Three Layers in mature hair
    • medulla → large vaculated cells
    • cortex → cuboidal cells with hard keratin
    • cuticle (outermost) → squamous cells with hard keratin
  • root sheath
  • dermal sheath → CT surrounding follicle
65
Q

Hair Growth

A

matrix cells proliferate in bulb

melanosomes ad pigment

matrix cells differentiate into keratin-producing cells

66
Q

What happens at the root bulb?

A

Melanocytes donate pigment

67
Q

Nails

A

dorsal surface of fingers and toes

keratinized epithelial cells

68
Q

What does the nail plate correspond to in the epidermis?

A

stratum corneum

69
Q

what does the nail bed correspond to in the epidermis?

A

stratum spinosum

stratum basale

70
Q

Nail Structure

A

hard keratin

hyponychium and eponychium are continuous with stratum corenum

71
Q

Define: Hyponychium

A

secures nail plate to finger tip

72
Q

Define: Eponychium

A

protects nail root

73
Q

Nail Development

A

Nail matrix produces cells of the root → stem cells, epithelial cells

lunula at base of nail is white due to partial keratinization of cells

nail plate moves over the nail bed

74
Q

Skin Repair: Scrape

A

no bleeding

no loss of stratum basale

regeneration without scarring

only lose avascular tissue

75
Q

Skin Repair: Incision/Laceration

A

full thickness of skin but minimal loss of basal cells

surgical wounds

healing by first intention → not much debris present

thin injury

may need stitches → minimal scarring

76
Q

Skin Repair: Severe Injury

A

Substantial loss of basal cells

presence of foreign material/infection

healing by second intention

77
Q

Healing by Second Intention

A
  1. Neutrophil infiltration → remove debris
  2. Scar formation → areas of fibrous → infiltration of granulation tissue (Fibrous CT)
  3. slow regeneration from edges
78
Q

The epidermis is comprised of…

A

stratified squamous keratinized epithelium that provides a strong barrier, resistance to abrasion, and a water barrier

79
Q

The layered appearance of the epidermis is due to…

A

altered appearance of keratinocytes during their differentiation

80
Q

The dermis is comprised of…

A

loose CT (papillary layer) and dense irregular CT (reticular Layer) with elastic fibers

81
Q

The skin has both ___ glands and __ structures

A

The skin has both sweat glands (eccrine and apocrine) and specialized structures

82
Q

Both hair follicles and nails are….

A

specialized epithelium with elements in common with the epidermis

83
Q

The ___ is not part of the integument, but is closely associated with it.

A

The hypodermis is not part of the integument, but is closely associated with it.

Histo 1 (13 decks)

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