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Integument Flashcards

(111 cards)

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1
Q

What is the epidermis?

A

Location: Epithelial covering of the skin
Highly cellular tissue with essentially no intercellular space
Function: protective barrier (physical, biological, and chemical insults)
Avascular (dependent on diffusion from dermal vasculature)
Minimally innervated

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2
Q

What is the dermis?

A

Contains supportive connective tissue layer with a strong extracellular matrix component with comparatively few cells
Highly vascularized and innervated
Most skin appendages are found here

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3
Q

What is the hypodermis

A

Similar to superficial fascia
Primarily adipose compartmentalized by other connective tissues (highly vascular)
Function:
1) insulation
2) allows skin to move independent of muscles

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4
Q

What are the skin appendages?

A

Hair follicles
Nails
Sweat glands
Sebaceous glands

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5
Q

What epithelium makes up the epidermis?

A

Stratified squamous orthokeratinized epithelium

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6
Q

What is stratified squamous orthokeratinized epithelium?

A

Multilayered tissue where the most superficial cells are flattened
Covered superficially by sheets of keratin (remnants of dead cells)
separated from underllying dermis by a basement membrane

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7
Q

What is the Basement membrane?

A

Non-cellular sheet of protein basal to most epithelia
difficult to see directly with light microsopy
provides adhesion interface for epithelial tissues
Function: serves as filtration barrier between compartments

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8
Q

What does stratum mean?

A

Single Layer

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9
Q

What is the principle cell type found in Epidermis?

A

Keratinocyte

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10
Q

What is the function of keratinocytes?

A

differentiates to produce keratin and keratohylin granules

° also produces and secretes large amounts of glycolipid which creates a water barrier

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11
Q

Where are keratinocytes found?

A

originates deep in the epidermis and takes about 4 weeks to move to the surface

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12
Q

Where is the stratum basale located?

A

first layer of cuboidal to low columnar cells sitting on the basement membrane

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13
Q

What does the stratum basale contain?

A 
Contains mitotic cells that continually give rise to new keratinocytes
Many desmosomes (cell-cell) and hemidesmosomes (cell-BM) present
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14
Q

Where do the hemidesmosomes in the stratum basale connect to?

A

From the cells to the basement membrane

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15
Q

What is the primary cytoskeletal protein in epithelial cells?

A

Keratin

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16
Q

What is the stratum spinosum?

A

Layer superficial to Stratum basale
Variable in thickness from a few to several cell layers thick
Polyhedral shaped cells linked by spine-like processes that contains desmosomes made apparent by shrinkage artifact

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17
Q

What is the Stratum granulosum?

A

Only a few cells thick; squamous shaped cells
Contain distinct basophilic keratohylin granules
Also contain large amount of keratin filaments at this time
Last layer of living cells

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18
Q

What is the stratum lucidum?

A

Clear layer only seen in skin from palms and soles (glabrous skin)
Thin transparent layer only a few cell layers thick
Cells here have died and lost their organelles (including the nucleus)

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19
Q

What is the Stratum Corneum?

A

Keratinized or cornified layer of dead keratinocytes
Compact sheets of keratin fibers; variable thickness (eg., calluses)
Glycolipid released into the intercellular space forms the water barrier

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20
Q

What is glabrous (thick) skin and hairy (thin) skin based relative to?

A

Epidermis only

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21
Q

Where is glabrous skin found?

A

found on palms of hands and soles of feet

Hairless skin with a thick epidermis (substantial keratinized layer)

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22
Q

Where is Hairy (thin) skin found?

A

Hairy or thin skin - found on remainder of body

Has hair follicles and a thin epidermis (thinner layer of keratin)

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23
Q

What is the total thickness of skin measured by?

A 
Total thickness (epidermis+dermis+hypodermis)
So, Thin skin is thicker than thick skin
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24
Q

What is Psoriasis?

A

chronic skin disorder characterized by dark red circumscribed lesions with
obvious superficial silvery white scales

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25
What is Psoriasis caused by?
Due to accelerated keratinocyte turnover - mitosis occurs in the three deepest layers of epidermis - overproduced keratinocytes reach surface in less than 1 week - not enough time to allow adequate maturation of keratinocytes - stratum corneum fails to become strongly cohesive layer
26
What are melanocytes and where are they found?
pale staining dendritic cell found interspersed in the stratum basale
27
What is the function of melanocytes?
Produce a brown pigment called melanin - Constitutively secreted by melanocytes and phagocytosed by keratinocytes - Colors the skin and protects from ultraviolet ray penetration
28
Do people of all races have melanocytes?
Yes
29
What is the concentration of melatocytes to keratinocytes?
10 - 25%
30
What is the effect of melanocytes on skin color?
- Light skinned people store melanin in basal keratinocytes and have a faster rate of lysosomal degradation - Dark skinned people store melanin in all layers of the epidermis and have a much slower rate of lysosomal degradation
31
What occurs in albino people?
albino people have genetic defect making melanin production impossible
32
What are langerhans cells an what are their function?
Pale staining dendritic cell located in the three deepest layers of epidermis Antigen presentation cell involved in cell mediated immune responses in the skin
33
What are Merkel cells?
clear cell located in stratum basal where it synapses with an afferent neuron
34
What is the function and location of merkel cells?
Prevalent where sensory perception is acute (e.g., fingertips) Functions as a mechanoreceptor for light touch
35
What is the dermis primarily made up of?
primarily dense irregular connective tissue containing the skin appendages
36
What does the "dense irregular" of dense irregular connective tissue refer to?
How thick the actual collagen strands are and not how densely packed they are. Also, the irregular = no pattern
37
What is Dense Irregular Connective Tissue made up of?
thick bundles of Type I collagen running in multiple planes
38
What is the most abundant extracellular fibrillar protein?
Type I Collagen
39
What is the function of Dense Irregular Connective Tissue?
functions to limit range and direction of movement in multiple directions
40
Is the dense irregular Connective tissue able to repair itself after injury?
Yes because it is usually well vascularized and well innervated
41
What are elastic fibers?
Composed of fibrillin and elastin proteins and intermixed among the type I collagen
42
What is the elastic fibers' function?
unctions to allow tissue to recoil after having been stretched
43
What fills the spaces between the CT fibers and the cells?
Ground substance
44
What is ground substance primarily made of?
Glycosaminoglycans (GAGs)
45
What are GAGs?
``` Large unbranched polysaccharide chains of repeating disacchraides Usually attached to a protein core (creating a proteoglycan monomer) High negative charge Strongly hydrophilic (can't fold; permanently open configuration) ```
46
What is the function of ground substance
functions to facilitate diffusion between cells and capillaries
47
What is the most-commonly seen cell in dense irregular CT?
Fibroblasts
48
What are fibroblasts?
Spindle shaped cell with long cytoplasmic processes | Round to elongated oval shaped nucleus with nucleolus
49
What is the function of fibroblasts?
functions to produce all the matrix components in general connective tissue also maintains and repairs CT matrix
50
What is the second most common cell in dense irregular CT?
Macrophages
51
What are the function of the macrophages?
major functions are phagocytosis and antigen presentation
52
What is the Papillary Dermis?
fairly narrow region immediately deep to epidermis
53
Function of the papillary dermis?
very undulating interface exists here; contributes to adhesion
54
What are dermal paillae
dense irregular CT projections up underneath epidermis
55
What are rete pegs?
epithelial extensions down into CT
56
What is the reticular dermis?
Thicker area deep to the papillary layer
57
What does the reticular dermis consist of?
Coarser dense irregular CT (as compared to papillary dermis) with elastic fibers Contains blood vessels, lymphatics and nerves of skin
58
What is the main area of the dermis?
The reticular dermis because the integrity is based on this layer
59
What are dermatoglyphics
fingerprints Epidermal ridges corresponding to underlying dermal ridges Dermal ridges result from rows of dermal papillae
60
What are blisters
usually formed by excessive sheering at the dermal/epidermal interface
61
What are langer's lines?
parallel lines of tension in skin resulting from organized bundles of collage and elastic fibers Surgical incision heal with least scarring when made parallel to these lines
62
How does blood reach the skin?
``` Subcutaneous arteries (deep in the hypodermis) send branches to the junction between the reticular layer of dermis and the hypodermis (superficial fascia) ```
63
Where is the deep plexus?
between the hypodermis and the reticular dermis
64
Where is the superficial plexus?
between the reticular dermis and the papillary dermis
65
What is the epidermis nourished by?
epidermis is nourished by diffusion from dermal papillary capillaries
66
What extends into each dermal papilla?
Capillary loops that extend from the superficial plexus
67
What is the Arterioenous anastomoses?
Direct connection between arterial and venous vessels bypassing capillary beds • Required for thermoregulation • May be gated as necessary by the ANS
68
Where are Arterioenous anastomoses found?
located between the two plexuses
69
What are mechanoreceptors?
stimulated by compression or tension
70
What are thermoreceptors?
stimulated by temperature
71
What are nociceptors?
stimulated by chemical irritants (pain)
72
What is the rank of touch from light to heavy?
``` Merkel Cells (stratum basale) Meissner's corpuscle (dermal papillae) Pacinian Corpuscle (dermis/hypodermis) ```
73
What are free nerve endings?
Not associated to Schwann Cells | Most numerous and function in mechanoreceptors, thermoreceptors and nociceptors
74
What are encapsulated nerve endings?
Surrounded by modified Schwann cells
75
What is a Meissner's corpuscle?
mechanoreceptor sensitive to light touch | flat Schwann cells with a helical neuron
76
Where are Meissner's Corpuscles located?
located in dermal papillae (especially on palms and fingertips
77
What are Pacinian corpuscles?
Mechanoreceptor sensitive to deep pressure | Quite large with concentric rings of Schwann cells and central neuron
78
Where are the Pacinian corpuscles located?
located at dermis/hypodermis interface
79
What are Ruffini corpuscles?
Mechanoreceptor sensitive to tension | Small spindle shaped receptor found interspersed among the collagen bundles
80
What are nails?
protective covering on dorsal surface of terminal ends of fingers/toes
81
Does hair grow continuously?
No
82
What makes up the hair shaft?
multiple layers of highly organized keratin
83
What makes up the hair follicle?
tubular downgrowth of epidermis into dermis and hypodermis
84
What is the arrector pili muscle?
narrow band of smooth muscle associated with each hair | * runs obliquely to the foYicle and causes the shaft to become erect (ie goose bumps)
85
What does exocrine mean?
Must have a duct, where secretions will flow and release secretions to
86
What does endocrine mean?
No duct
87
What is a simple gland?
No branching, only goes to one destination
88
What does acinar mean?
Cluster shape
89
What are sebaceous glands?
Simple Acinar Exocrine Glandular outgrowths from the hair follicle Fairly inactive prior to puberty; large and secretory following puberty Large polyhedral pale staining cells; mitotically active peripherally in gland
90
What is sebum?
oily secretory product released by holocrine secretion
91
What type of gland are eccrine sweat glands?
simple tubular exocrine glands
92
Where are eccrine sweat glands found?
Secretory region is coiled and located in the reticular dermis Excretory region passes through papillary dermis and epidermis to surface Located everywhere in skin but especially concentrated in: forehead, scalp, axillae, palms and soles
93
What is the function of the eccrine sweat glands?
secrete sweat which is important for temperature regulation
94
What are appocrine sweat glands associated with?
associated with hair follicles
95
Where are appocrine sweat glands located?
located in the axilla, areola and nipple, circumanal region, external genitalia
96
What is the function of appocrine sweat glands?
Secretion is initially odorless but bacterial action on the skin creates an odor Secretion may function as pheromone
97
What is Loose (Areolar) connective Tissue?
Mostly thin, lacy Type I collagen fibers Fairly fluid-like ground substance Variety of immune cells may be present but here it's mostly fibroblasts
98
Where is Loose (areolar) connect tissue found?
located among loops of sweat glands, within adipose, deep to the epithelial linings of the Gl and respiratory tracts, and in dissectable tissue planes in Gross lab
99
What are the functions of loose connective tissue?
functions in packing, binding and anchoring in relatively small areas ~ often has a role in immune function
100
What is the hypodermis?
Equivalent to superficial fascia Varies greatly in thickness from glabrous to abdominal skin Major component is adipose
101
What are adipocytes?
mature adipocytes are non mitotic (terminal cell) | o stem cells exist to provide additional adipocytes throughout life
102
What do adipocytes look like?
Signet ring ejppearance (diameter 100 J.lm or more) Large lipid droplet pushes the nucleus and cytoplasm peripherally Adipocytes are held together by thin strands of Type I collagen (difficult to discern) Clumps of adipocytes are compartmentalized by seams of dense irregular CT
103
What is the function of adipocytes?
Long term energy reserve source | Insulates against heat loss, fills crevices and cushions
104
What is uniocular adipose?
``` White fat (yellow); ubiquitous in the body Adult form of fat most commonly present ```
105
What is the structure of uniocular adipose?
Spherical/polygonal cells usually clustered in groups Appears yellow Grossly and usually white Histologically Each cell contains a single large lipid droplet which pushes organelles peripherally
106
What is the function of uniocular adipose?
Lipid storage as the body's long term energy reserve | Insulation, shock absorption and "body contouring"
107
What is Multiocular adipose?
Brown fat Most common in newborns (disappears in adult) Typical kind of fat seen in hibernating animals
108
What is the structure of multiocular adipose?
Smaller cells than those in unilocular fat | each cell contains, multiple small lipid droplets and many mitochondria
109
What is the function of multiocular adipose?
metabolize fat to produce heat
110
Where is the stratum basale located?
Sits on the basement membrane
111
What does the stratum basale contain?
``` Mitotic cells that give rise to new karatinocytes Contain desmosomes (cell - cell)and hemidesmosomes (cell-BM) ```

Histology (9 decks)

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