Integument Flashcards

1
Q

what is the integument?

A

the largest organ in the body that generally functions as a protective barrier against injury

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2
Q

what is the integument composed of?

A

skin and skin appendages

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3
Q

what are the skin appendages?

A
  • nails
  • hair
  • sweat glands
  • sebaceous glands
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4
Q

at mucocuntaneous junctions, the skin is ____________ with mucous membranes that line ___________, __________, and ____________ tracts.

A

continuous
digestive, respiratory, urogenital

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5
Q

functions of the skin

A

protective barrier against:
- injury (abrasions, cuts, burns)*
- infectious pathogens
*
- UV radiation
- body temp regulation*
- vitamin D synthesis
- ion excretion
- sensory reception
*

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6
Q

why is vitamin D important?

A

helps with normalizing blood levels of calcium and phosphorous

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7
Q

what is an important quality of the skin?

A

it has a remarkable regenerative capacity

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8
Q

what type of epithelia is the integument composed of on the epidermis?

A

stratified squamous keratinized epithelium

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9
Q

the general organization of the layers of integument:

A
  • epidermis
  • dermis
  • hypodermis
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10
Q

embryologically, what does the epidermis and its appendages derive from?

A

surface ectoderm

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11
Q

embryologically, what does the dermis derive from?

A

mesoderm

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12
Q

what is the skin composed of?

A
  • keratinocytes (90%)
  • melanocytes
  • Merkel cells
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13
Q

embryologically, what does the Merkel cells and the melanocytes derive from?

A

the neural crest

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14
Q

which layer produces vitamin D?

A

the epidermis
- sunlight catalyzes the reaction of vitamin D3 production

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15
Q

schematic of skin and its appendages

A
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16
Q

what structures are included in the epidermis layer:

A
  • hair shaft
  • pore of sweat gland
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17
Q

what are the layers of the epidermis?

A
  • stratum corneum
  • stratum lucidum
  • strautm granulosum
  • stratum spinosum
  • stratum basale
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18
Q

stratified corneum

A
  • most superficial layer
  • 20-30 layers
  • cells are flat, dead, anucleated, and keratin filled karatinocytes
  • protects against friction and water loss
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19
Q

stratum lucidum

A
  • 2-3 layers of dead, anucleated cells
  • only seen in thick skin
  • see through
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20
Q

stratum granulosum

A
  • 3-5 layers of keratinocytes
  • distinct keratino-hyaline granules
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21
Q

stratum spinosum

A
  • several layers of keratinocytes
  • all joined by desmosomes (“spines”)
  • when integument is fixed, they shrink but stay attached to desmosomes and appear to look like they have spines
  • Langerhans cells present
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22
Q

stratum basale

A
  • deepest, single layer
  • cubodial to low columnar cells
  • in contact with basement membrane
  • mitosis occurs here
  • has merkel and melanocytes
    “germinal layer”
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23
Q

layers of the dermis

A
  • papillary layer
  • reticular layer
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24
Q

papillary layer of dermis

A
  • more superficial layer of dermis
  • composed of connective tissue
  • forms dermal papillae
  • contains subpapillary vascular plexus
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25
Q

reticular layer of dermis

A
  • deeper layer of dermis
  • dense irregular connective tissue
  • surround hair follciles, sebaceous glands, sweat glands, nerves, deep plexus of blood vessels extending into subcutaneous layer
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26
Q

subcutaneous layers

A
  • are not specific layers
  • are not considered integument
  • deep to dermis
  • composed of adipose connective tissue
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27
Q

characteristics of thick skin:

A
  • thick epidermis
  • thick stratum corneum
  • stratum lucidum
  • no hair
  • no arrector pilli
  • no sebaceous glands
  • many sweat glands
  • dermatoglyphs (fingerprints)
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27
Q

where is thick skin located?

A
  • palms/soles
  • finger tips (dermatoglyphs)
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28
Q

characteristics of thin skin:

A
  • thinner than thick skin
  • thin stratum corneum
  • no stratum lucidum
  • hair
  • arrector pilli
  • sebaceous glands
  • sweat glands
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28
Q

where is thin skin located?

A

everywhere but palms/soles

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28
Q

what is the key difference between thick and thin skin?

A

thick has stratum lucidum !! and thin does not

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29
Q

what layer can you find Meissner corpuscles?

A

DERMIS

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29
Q

histological stain of skin compared to cartoon image

A
29
Q

characteristics of epidermis

A
  • derived from surface ectoderm
  • avascular
30
Q

in the stratum basale, keratinocytes form a __________ to __________ epithelial layer

A

cuboidal, columnar

30
Q

what kind of cells are in the stratum basale

A
  • keratinocytes
  • melanocytes
  • Merkel cells
31
Q

characteristics of keratinocytes in stratum basale

A
  • sit on basal lamina
  • from single layer
  • mitotic/dividing
  • cuboidal-shaped
  • basophilic cells with large nucleus
  • young, immature
  • least differentiated
  • supposed to die
  • produce keratin
32
Q

keratinocytes connect to each other via ____________ and connect to the basement membrane via ______________.

A

desmosomes, hemidesmosomes

33
Q

how does the epidermis renew?

A
  1. immature basal cells divide
  2. dividing cells differentiate and push cells to surface as they migrate
  3. mature/differentiated/ keratinized cells are superficial layers
34
Q

where does basal cell carcinoma and squamous cell carcinoma originate?

A

keratinocytes

35
Q

melanocytes are restricted to what layer?

A

stratum basale

36
Q

characteristics of melanocytes

A
  • spider shaped
  • derived from neural crest
  • synthesize melanin
  • determine hair and skin color
  • same number in all races
  • protects from UV radiation
37
Q

synthesis of melanin

A
  • UV triggers synthesis
  • granules of melanin spread by cytoplasm
  • UV turns on transport by dynein on microtubules to nucleus
  • melanin protects from UV radiation
38
Q

characteristics of Merkel cells

A
  • located in stratum basale
  • sensory cells
  • spikey disc-shaped mechanoreceptors
  • sense light touch, form, texture
  • abundant in finger tips
39
Q

types of cells in stratum spinosum

A
  • keratinocytes
  • Langerhan cells
40
Q

characteristics of keratinocytes in stratum spinosum

A
  • desmosome spines
  • abundant melanin
  • lamellar (membrane-coating) granules
    (glycolipids, released in stratum granulosum, water-proofing, block diffusion of nutrients from dermal blood vessels to superficial cells)
41
Q

characteristics of Langerhan cells

A
  • Epidermis specific macrophages (immune cells)
  • Antigen presenting
  • Monocyte-derived from bone marrow
42
Q

how do Langerhan cells present antigens?

A

presence of CD4+ and CD8+ T lymphocytes

43
Q

cells in stratum granulosum

A
  • keratinocytes
44
Q

characteristics of keratinocytes in stratum granulosum

A
  • several flat layers
  • last layer with nuclei
  • anucleate and pyknotic nuclei
  • keratohyaline granules!!!
  • lamellar granules
45
Q

why are keratohyaline granules important?

A
  • they help produce keratin
  • protect epidermis
46
Q

cells in stratum lucidum

A
  • keratinocytes
47
Q

characteristics of keratinocytes in stratum lucidum

A
  • clear, light staining layer
  • flat, dead cells
  • thick skin only
  • keratohyaline and keratin filaments
  • eleiden = clear protein
48
Q

characteristics of dermis

A
  • derived from mesoderm
  • HIGHLY vascularized
  • glomus cells
  • lots of elastic tissue
  • contained epidermally-derived structures
49
Q

why are glomus cells important?

A
  • they are modified smooth muscle cells
  • create a shunt
50
Q

characteristics of superficial papillary layer of dermis

A
  • loose connective tissue
  • dermal papillae
  • capillary roots (thermoregulation)
  • free nerve endings (pain, hot/cold)
  • Meissner’s corpuscles (light touch)
  • lamellar corpuscles
  • superficial plexus
51
Q

characteristics of deep reticular layer

A
  • dense irregular connective tissue (collagen, elastic fibers)
  • majority of dermis
  • pacinian corpuscles (deep pressure, vibration)
  • deep dermal plexus
52
Q

vasculature of integument

A

blood in arteries > arterioles > hypodermis > dermis > each papilla > venules > veins > leave integument

53
Q

why are arterio-venous shunts important?

A

keep heat in by not bypassing capillaries of the surface and keeping blood in deeper layers

54
Q

what controls opening between arteriole and venule?

A

glomus body

55
Q

hypodermis

A
  • derived from ectoderm
  • filled with unilocular adipocytes
  • attaches to skin underlying structures
  • permits movement over most body parts
56
Q

tactile receptors

A
  • Merkel cells
  • free nerve endings
  • root hair plexuses
  • meissner corpuscles
  • lamellated (pacinian) corpuscles
  • krause and bulbs
  • ruffini corpuscles
57
Q

merkel cells as tactile receptors

A
  • associated with expanded nerve endings
  • function as tonic receptors for sustained light touch and for sensing an objects texture
58
Q

free nerve endings as tactile receptors

A
  • in papillary dermis
  • extend into lower epidermal layers
  • respond to high and low temperatures
  • pain
  • itching
59
Q

root hair plexus as tactile receptors

A
  • innervates the hair and secretion of sebaceous glands
  • surround bases of hair follicles in reticular dermis
  • detects movement of hairs
60
Q

meissner corpuscles as tactile receptors

A
  • in fingertips, palms, and soles
  • decline with age
  • sensory axons winding among flattened schann cells arranged perpendicular to epidermis in dermal papillae
  • elliptical structures
  • initiate impulses with light touch
61
Q

lamellated (pacinian) corpuscles as tactile receptors

A
  • large oval structures
  • deep in reticular dermis and hypodermis
  • outer capsule
  • concentric lamellae of flatted schwann cells and collagen surrounding a highly branched unmyelinated axon
  • deep touch sense
  • found in connective tissue of organs
  • wall of rectum and urinary bladder
62
Q

krause and bulbs as tactile receptors

A
  • simpler encapsulated ovoid structures
  • thin
  • collagenous
  • found in skin of penis and clitoris where they sense low frequency vibrations
63
Q

ruffini corpuscles as tactile receptors

A
  • collagenous, fusiform capsules
  • anchored firmly to the surrounding connective tissue with sensory axons stimulated by stretch or twisting of skin
64
Q

location of glands of skin

A

within lower part of dermis/hypodermis

65
Q

types of skin glands

A
  • sebaceous
  • sudoriferous (eccrine/apocrine)
66
Q

sebaceous (holocrine) glands

A
  • oily secretion (sebum)
  • release by bursting via holocrine
  • located in hair follicle
  • can cause acne
67
Q

eccrine glands

A
  • eccrine/merocrine
  • almost everywhere
  • simple, coiled, tubular
  • stratified cuboidal duct
  • deep
68
Q

apocrine glands

A
  • axillary and anogential areas
  • odorless secretion but has bacteria (BO)
  • active after puberty
  • larger acini and larger lumen
69
Q

characteristics of hair appendages

A
  • epidermal
  • penetrate dermis and hypodermis
  • sebaceous glands are next to the hair shaft
  • secrete sebum here
  • arrector pilli (goose bumbs, and raise hair)
70
Q

skin in wound healing

A
  1. blood clotting at wound and release platelets
  2. macrophages and neutrophils enter wound as inflammation begins
  3. epithelial cells from cut edges begin to migrate through clot
  4. fibroblasts proliferate and produce new collagen to for granulation tissue
  5. epidermis regenerates
71
Q

psoriasis

A
  • chronic relapsing disorder
  • at elbows, knees, scalp, and lumbosacral regions
  • “T lymphocyte autoimmune disease”
  • red plaques covered by silver to white scales
72
Q

what causes psoriasis?

A
  • T-Lymphocyte autoimmune disease
  • Increased numbers of Langerhans cells and T-cells
  • Mitosis above stratum basale
73
Q

treatments of psoriasis

A
  • topical and system medications
  • UV light
  • biological therapies
74
Q

what is lamina propria

A

the layer of connective tissue that connects epithelial cells to smooth muscle in mucous membranes