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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
Define: Melanocytes
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
26
Why does melanin go to keratinocytes?
it surrounds the nucleus of keratinocytes to protect from non-ionizing UV damage prevents formation of cancer
27
How does the keratinocyte obtain the melanin?
keratinocyte eats the melanocyte and picks up melanosome
28
What is constant regardless of skin tone?
melanocyte/keratinocyte ratio is constant
29
What differs depending on skin tone?
melanosome size, number, and rate of degradation
30
Melanocyte/Keratinocyte Pigment donation process
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
31
UV exposure alters:
Rate of melanin production through activity of tyrosinase → increases melanin production chemical nature of melanin (appears darker) → increases protection
32
Define: Langerhans Cells
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
33
Define: Merkel's Cells
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
34
Define: Merkel's Corpuscle
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
Define: Thick Skin
palms and soles sweat glands hairless no sebaceous glands → associated with hair follicles
36
Define: thin skin
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
How to differentiate thick vs thin skin?
look for → epidermal layers and hair
38
Epidermal - Dermal Junction
* Basal lamina connected to keratinocytes * interdigitations * dermal ridges
39
How is the basal lamina connected to keratinocytes?
intermediate filaments by hemidesmosomes microfilaments by focal adhesions
40
Define: Rete Ridges
projections of epidermis
41
Define: Dermal Papillae
projections of dermis
42
Function of the Epidermal - Dermal Junction
increase surface area → attachment and nutrient exchange much deeper ridges at sites of abrasion
43
General Structure of the Dermis
loose CT next to epidermis dense irregular beneath it
44
Define: Dermis: Papillary Layer
Loose CT with → small blood vessels , nerves, lymphatics, meissner's corpuscles collagen types I and III elastic fibers
45
Define: Dermis: Reticular Layer
Between papillary layer and hypodermis dense irregular CT with → larger nerves and blood vessels, hair follicles, pacinian corpuscles, ruffini end organs
46
Define: Langer's Lines
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
Dermis: Vasculature
temperature regulation arteriovenous anastomses shunt blood between two plexuses → subpapillary, cutaneous (reticular) less blood flow = retain body heat → regulated by smooth muscle
48
Define: Hypodermis
aka the Superficial Fascia Loose CT and adipose tissue anchors skin to underlying tissue bases of sweat glands and hair follicles
49
Integumentary glands
eccrine apocrine sebaceous
50
Eccrine Gland
secretes sweat simple duct coiled tubular secretory duct empties into surface of skin located almost everywhere
51
Apocrine Gland
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
Sebaceous Gland
secretes by holocrine method secretes lipids branched duct acinar (ball shaped) secretory duct empties into hair follicle located in hair and eyelid
53
What is the reason you can quickly go from not sweating to sweating in sweat glands?
myoepithelial cells → contract to aid in sweat expulsion surround the glandular cells
54
What innervation do sweat glands have?
sympathetic autonomic
55
Where are eccrine sweat glands not located?
in lips and external genitalia
56
What type of secretion do eccrine sweat glands have?
water → secrete urea, water, salts, etc. regulate body temp
57
What are the differences between eccrine and apocrine glands?
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
Define: Nonencapsulated
free nerve endings in the epidermis detect touch, pressure, heat, cold, pain associated with hair follicles (mechanoreceptors) can be associated with merkel cells
59
Define: Encapsulated
ruffini ending (dermis) meissner's corpuscle (dermal papillae) Pacinian Corpuscle (dermis and hypodermis)
60
Define: Ruffini Ending
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
Define: Meissner's Corpuscle
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
Define: Pacinian Corpuscle
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
Hair Follicles
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
Hair Structure
* 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
Hair Growth
matrix cells proliferate in bulb melanosomes ad pigment matrix cells differentiate into keratin-producing cells
66
What happens at the root bulb?
Melanocytes donate pigment
67
Nails
dorsal surface of fingers and toes keratinized epithelial cells
68
What does the nail plate correspond to in the epidermis?
stratum corneum
69
what does the nail bed correspond to in the epidermis?
stratum spinosum stratum basale
70
Nail Structure
hard keratin hyponychium and eponychium are continuous with stratum corenum
71
Define: Hyponychium
secures nail plate to finger tip
72
Define: Eponychium
protects nail root
73
Nail Development
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
Skin Repair: Scrape
no bleeding no loss of stratum basale regeneration without scarring only lose avascular tissue
75
Skin Repair: Incision/Laceration
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
Skin Repair: Severe Injury
Substantial loss of basal cells presence of foreign material/infection healing by second intention
77
Healing by Second Intention
1. Neutrophil infiltration → remove debris 2. Scar formation → areas of fibrous → infiltration of granulation tissue (Fibrous CT) 3. slow regeneration from edges
78
The epidermis is comprised of…
stratified squamous keratinized epithelium that provides a strong barrier, resistance to abrasion, and a water barrier
79
The layered appearance of the epidermis is due to…
altered appearance of keratinocytes during their differentiation
80
The dermis is comprised of…
loose CT (papillary layer) and dense irregular CT (reticular Layer) with elastic fibers
81
The skin has both ___ glands and __ structures
The skin has both sweat glands (eccrine and apocrine) and specialized structures
82
Both hair follicles and nails are….
specialized epithelium with elements in common with the epidermis
83
The ___ is not part of the integument, but is closely associated with it.
The hypodermis is not part of the integument, but is closely associated with it.

Histo 1 (13 decks)

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