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unit 1 Flashcards

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1
Q

epithelium

A

avascular tissue that covers the exterior body surface, lines internal closed cavities and body tubes that communicate with the exterior

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2
Q

epithelium forms what portion of glands?

A

the secretory portion and their ducts

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3
Q

epithelium provides

A

a selective permeable barrier between the external environment and underlying connective tissue

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4
Q

three principal characteristics of epithelium

A

closely apposed to each other by cell-to-cell adhesions via cell junctions
exhibit functional and morphological polarity
basal surfaces attach to an underlying basement membrane

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5
Q

what are the two extracellular structures separating epithelium from CT

A

basal lamina and basement membrane

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6
Q

basal lamina

A

structural attachment site for over-lying epithelial cells and underlying CT

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7
Q

what is the basement membrane

A

basal lamina and the underlying contributions of the connective tissue

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8
Q

all epithelia rest upon what

A

a basement membrane

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9
Q

are basal lamina and basement membrane synonymous?

A

no

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10
Q

what are the three layers of the basement membrane

A

lamina lucida, lamina densa, lamina fibroreticular

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11
Q

what are components of the basement membrane

A

type IV collagen, laminin

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12
Q

what is classification of epithelium based on?

A

number of cell layers and shape of the surface cells

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13
Q

simple squamous cells are usually joined together by what

A

intercellular junctions

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14
Q

where can simple squamous cells be found

A

lining Bowman’s capsule, blood and lymphatic vessels, pleural and abdominal cavities

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15
Q

what do simple squamous epithelium permit

A

diffusion and bidirectional movement of gases, fluids, and nutrients from the free surface to underlying tissue

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16
Q

simple cuboidal epithelium

A

provides protection, forms conduits for gland ducts, may be specialized for active secretion and absorption

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17
Q

where are simple cuboidal epithelium found

A

in glands, salivary ducts, pancreas and kidney

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18
Q

simple cuboidal epithelium may have

A

microvilli or cilia

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19
Q

where are simple columnar epithelium mainly found

A

in areas engaged in protection of wet surfaces, nutrient absorption, and secretion

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20
Q

simple columnar epithelium often have what on free surfaces

A

microvilli

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21
Q

where are stratified squamous epithelium found

A

in areas that need protection from abrasion, i.e. skin

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22
Q

where are stratified cuboidal epithelium usually found

A

lining ducts of sweat glands and exocrine glands

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23
Q

where are stratified columnar epithelium usually found

A

pharynx, larynx, conjunctiva of eyelids, major ducts of exocrine glands, anorectal junction, parts of the male urethra

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24
Q

two special classifications of epithelium

A

psuedostratified and transitional

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25
pseudostratified epithelium
some cells do not reach the free surface, but all rest on the basement membrane
26
transitional epithelium
lines lower urinary tract, extends from major calyces to proximal part of urethra
27
microvilli
cytoplasmic projections on the apical surface of most epithelial cells anchored to villin at the tip of the microvillus
28
terminal web
composed of actin filaments stabilized by spectrin, which anchors it to the apical cell membrane
29
stereocilia, in the repro track
immotile microvilli of an unusual length, function to facilitate absorption
30
stereocilia, in the ear
sensory epithelium that are sensitive to mechanical vibration, serve as mechanoreceptors high density of actin cross-linked by espin
31
stereocilia organization
internal bundles of actin filaments that are cross-linked by fibrin organization is similar to microvilli, longer, anchored by ezrin to the plasma membrane
32
cilia
hair-like extensions of the apical plasma membrane
33
primary cilia
function as signal receptors that sense the flow of fluid in organs - mechanoreceptors mutations in PKD affect the development of primary cilia, leads to disease
34
nodal cilia
present only embryologically, establishes the left-right asymmetry of internal organs
35
glands are either
exocrine or endocrine
36
exocrine glands
release their secretory product into a duct or lumen of a hollow organ
37
endocrine gland
release their secretion into the circulation which distributes it to the target organs
38
three types of junctional complexes
occluding junctions, anchoring junctions, communicating junctions (gap junctions)
39
other names for occluding junctions
zonula occludens, tight junctions
40
anchoring junction types
zonula adherens, macula adherens, focal adhesions, hemidesmosomes
41
structural integrity of epithelium is maintained by
adhesion of the constituent cells both to each other and to structural extracellular matrix
42
adhesions are maintained by what two systems
cell membrane proteins that act as adhesion molecules specialized areas of cell membranes are incorporated in cell junctions
43
occluding junctions function
establish a barrier between different compartments of the body and allow epithelial cells to function as selective barrier
44
occluding junction proteins
4 groups of transmembrane proteins: Claudins occludin junctional adhesion molecule tricellulin
45
anchoring junctions function
mechanical stability, through anchoring the cytoskeleton of one cell to the cytoskeleton of an adjacent cell play a role in cell-to-cell recognition, morphogenesis and differentiation
46
types of cell-to-cell adhesion
zonula adherens, macula adherens
47
zonula adherens
interacts with network of actin filaments requires Ca++ cadherins and nectins
48
macula adherens
interacts with intermediate filaments desmogleins and desmocollins provide linkage between cell-to-cell membrane
49
types of anchoring cells to CT
focal adhesions, hemidesmosomes (found where cells anchor to extracellular materials like basal lamina)
50
gap junctions
allow for movement of larger molecules between cells formed by connexin proteins, six connexin make a connexon
51
integument
includes the skin, nails, hair, sweat glands, and sebaceous glands
52
layers of the skin
epidermis, dermis, hypodermis
53
skin categorization
thick or thin
54
rete ridges
form evagination of epidermis into the underlying dermis
55
cell types of the epidermis
keratinocytes, melanocytes, Merkel cells, Langerhans cells
56
layers of epidermis
stratum corneum stratum lucidum (only in thick skin) stratum granulosum startum spinosum stratum basale
57
stratum basale
single layer of cells that rests on the basal lamina and continuously divides to replace cells has extensive cell junction (desmosomes & hemidesmosomes) also contain melanin, is transferred to melanocytes
58
keratinocytes in stratum spinosum
keratinocytes with intercellular bridges and centrally located nucleus larger, several layers thick with apparent cytoplasmic processes or spines
59
stratum spinosum function
resist abrasion and shearing forces many desmosomes connect cytoplasmic processes
60
where is an increase of keratin produced?
stratum spinosum, assembled into keratin filaments that make the cytoplasm eosinophilic
61
what projects into the spines of the keratinocytes? what do they do?
tonofibrils (large bundles of keratin), connect to desmosomes at tip and link to spine of neighboring cells
62
keratinocytes of stratum granulosum
stratified layer 2-5 cells thick, most superficial nonkeratinized epidermis cytoplasm contain non-membrane bound granules that are strongly basophilic
63
keratohyalin granules
cystine and histidine rich proteins precursors of flaggrin
64
flaggrin
promotes tonofibril formation and keratinization
65
what are lamellar bodies? what do their contents form?
cytoplasmic secretary granules lipid-rich contents form extracellular sheets to create a barrier impermeable to water
66
when do cells undergo apoptosis in the epidermis?
as they exit stratum granulosum
67
stratum lucidum
only a few cell layers thick and only found in thick skin highly refractive, contains eosinophilic cells where keratinization is well advanced
68
stratum corneum
15-30 layers thick dead, flattened, desiccated cells filled almost entirely with keratin filaments
69
what is desquamation
when the most superficial cells of stratum corneum are shed
70
what is the major contributor to the protection/barrier function of epidermis?
stratum corneum
71
what is the predominant cell in the epidermis?
keratinocyte
72
how are melanocytes distributed??
to keratinocytes by phagocytosis
73
Merkel cell
ovoid cells with dense cytoplasmic granules
74
how do you get a Merkel disc?
Merkel cell + associated sensory nerve ending mechanoreceptor, LIGHT TOUCH!
75
where are Langerhans cells found?
in all layers of the epidermis, but primarily stratum spinosum
76
Langerhans cells
star shaped, dendritic type cell process and present cutaneous antigens to lymphoid cells
77
what are Langerhans cell essential for?
immune surveillance in skin
78
what are the two layers of the dermis?
papillary and reticular
79
what are the two parts of the epidermal-dermal junction?
dermal papillae and epidermal ridges (rete ridges)
80
what does the papillary layer of the dermis consist of?
loose CT, less abundant collagen fibers, fibroblasts, abundant mast cells and macrophages, some lymphocytes
81
what layer of the skin are blood vessels not found in?
epidermis
82
reticular layer of dermis
thicker, less cellular than papillary dense irregular CT with abundant blood vessels and nerve fibers, thick bundles of type I collagen, and course elastic fibers
83
hypodermis
loose CT often with abundant adipose, large blood vessels and nerve fibers are observed in this layer
84
what does the hypodermis do?
loosely binds skin to underlying organ and structures
85
what is the most common nerve supply to the skin?
free nerve endings (lack CT or Schwann cell)
86
where do free nerve endings terminate?
in stratum granulosum, often reach stratum corneum
87
what sensations do free nerve endings convey?
fine touch, heat, cold, pain
88
what are the encapsulated sensory receptors?
pacinian corpuscles, meissner's corpuscles, Ruffini's corpuscles
89
what are pacinian corpuscles?
deep pressure sensors found in deep dermis/hypodermis nerve endings surrounded by concentric layers of support cells
90
what are meissner's corpuscles?
fine touch, vibration, and pressure sensors found in dermal papillae layer nerve endings spiral thru corpuscle surrounded by few support cells
91
what are Ruffini's corpuscles?
encapsulated mechanoreceptor that detects pressure, temp, and stretching found in reticular layer of dermis
92
matrix cells
cells that give rise to keratinizing cells of hair shaft
93
dermal papilla (hair bulb)
tuft of loose CT at base of the hair bulb - vascular supply to hair follicle
94
where are sebaceous glands located?
between a hair follicle and its arrestor pili muscle in dermis
95
sebum
secretary product of lipid rich decomposed cells
96
what are sebaceous gland ducts composed of?
stratified squamous epithelium
97
what are eccrine sweat glands?
coiled secretory unit located deep in the dermis and straight duct that opens into the skin
98
what are the lumens of the secretory portion of the eccrine sweat gland lined by?
pseudostratified epithelium
99
what are the lumens of the ductus portion of the eccrine sweat gland lined by?
stratified cuboidal epithelium stain darker!!
100
what system controls eccrine sweat glands and what are they used for?
autonomic control, thermoregulation (heat and stress)
101
what do apocrine sweat glands do?
secrete a thick, odorous fluid into hair follicles for an unknown function
102
apocrine sweat glands
large lumen tubular glands associated with hair follicles
103
what epithelium lines the secretory portion of apocrine glands?
simple cuboidal
104
goblet cell
105
terminal bar
106
cilia
107
keratinized cell
108
urothelium dome shaped cell on top, tear drop shaped cell lower
109
mucous cell elongated nuclei, clear cytoplasm
110
serous cell
111
acinus
112
meissner's corpuscle
113
paccini corpuscle
114
sebaceous gland
115
apocrine gland
116
sebaceous gland

histology (15 decks)

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