Epithelial Tissue Flashcards
(121 cards)
1
Q
what does epithelia do? (3)
A
covers body surfaces
lines body cavities
forms glands
2
Q
epithelial cells are characterized by the production of — intermediate filaments
A
keratin
3
Q
do all epithelia produce the same type of keratin?
A
no, different epithelia produce different keratin
4
Q
keratin can be useful in
A
tumor ID
5
Q
what is keratin derived from? (3)
A
ecto, endo, mesoderm
6
Q
what is derived from the ectoderm? (5)
A
epidermis cornea/lens epithelial of eye enamel organ and enamel of teeth anterior pituitary inner ear
7
Q
what is derived from the neuroectoderm? (2)
A
neural tube (CNS) neural crest (PNS)
8
Q
neural tube (CNS) (5)
A
pineal body posterior pituitary sensory epithelium of eye ear nose
9
Q
neural crest (PNS) (6)
A
ganglia nerves glial cells adrenal medulla melanocytes neuroendocrine cells
10
Q
what is derived from mesoderm? (4)
A
epithelium of kidneys and gonads
mesothelium
endothelium
adrenal cortex
11
Q
what is derived from endoderm? (5)
A
respiratory epithelium
alimentary epithelium (except oral and anal cavity)
liver, pancreas, gallbladder, thyroid, parathyroid, thymus
epithelial lining of tympanic cavity and Eustachian tubes
transitional epithelium of bladder
12
Q
what are the epithelium functions? (6)
A
barrier SPM secretion absorption transport sensation
13
Q
do epithelia have blood vessels?
A
no they are avascular, they are never penetrated by blood vessels
14
Q
what separates the epithelium from underlying connective tissue and blood vessels?
A
the basement membrane
15
Q
cells rely on — of O2 and nutrients from underlying tissue
A
diffusion
16
Q
mucous membrane (mucosa)
A
epithelium that lines cavities that connect with outside world
(ex. alimentary, respiratory, or urogenital tracts)
17
Q
the mucous membrane contains (4)
A
surface epithelium of ectoderm (or endoderm)
basement membrane
supporting connective tissue (lamina proprietary)
smooth muscle (muscular mucosae)
18
Q
serous membrane (serosa)
A
epithelium that lines closed body cavities
ex. peritoneal, pleural, pericardial cavities
19
Q
serosa consists of (4)
A
epithelial lining
mesothelium (mesodermal derived)
basement membrane
supporting connective tissue
20
Q
what does serosa lack?
A
muscularis mucosae
21
Q
endothelium
A
epithelium that lines blood and lymph vessels (mesodermally derived)
22
Q
endothelium are associated with variable numbers of (2)
A
smooth muscle and connective tissue layers, or tunics
23
Q
most epithelial cells have a — lifespan
A
finite
24
Q
what is the basal surface of epithelial cells attached to>
A
underlying basement membrane and extracellular matrix proteins (external lamina)
25
functions of the basement membrane (5)
```
structural support
scaffolding for growth
differentiation
migration of cells during embryonic growth
regeneration
```
26
function of the non-cellular, protein and polysaccharide-rich layer
acts as a filter between epithelium and underlying connective tissue
27
how is negative charge maintained?
SPM for nutrients and metabolites to and from epithelium
28
function of the glomerular basement membrane in the kidneys
acts as a highly selective filter for urine formation
29
what are the major components of the basement membrane? (4)
GAGs
type 4 collagen
structural glycoproteins
large polypeptides with branched, polysaccaride side chains
30
structural glycoproteins (3)
laminin
fibronectin
enactin
31
what are the three layers of the basement membrane seen with electron microscopy?
```
lamina lucida (electron Lucent)
lamina densa (electron dense)
lamina reticularis (electron Lucent)
```
32
lamina lucida
in contract with the basal cell membrane
| 10-50 nm
33
lamina reticularis
merges with surrounding tissue
| 20-30nm
34
lamina densa
anchored to underlying connective tissue by microfibrils of type 4 collagen (anchoring filaments)
35
how do epithelial cells adhere to one another?
cell junctions
| intercellular epithelial attachment sites
36
cell junctions allow for
communication between cells
37
what are the three types of cell junctions?
occluding
adhering
communicating
38
occluding junctions are also known as
tight junctions
39
where are occluding junctions located?
beneath the luminal surface of simple columnar epithelia
40
occluding junctions act as
gaskets
41
zonula occludent
opposing cell membranes that fuse together
42
fascia occludens is present between
endothelial cells in the wall of blood vessels
43
adhering junctions are also known as
anchoring junctions
44
adhering junctions function to
bind cells together, act as anchoring points for cell cytoskeleton
45
zonula adherent
a continuous band characterized by transmembrane glycoproteins called cadherins
46
cadherins
class of cell adhesion molecules, or interns
47
in adhering junctions, are the adjacent cell membranes fused?
no
48
macula adherens/desmosomes
small, circular patches
49
most common type of cell junction
macula adherens/desmosomes
50
macula adherent/desmosomes are located on
the lateral surface of the cell
51
macula adherent/desmosomes are associated with attachment of plaques containing attachment proteins including (3)
desmoplakins
desmoglzins
tonofilaments
52
hemidesmosomes
half desmosomes
53
hemidesmosomes are found on the
basal surface of the cell
| anchoring it to the BM via integrins
54
hemidesmosomes are associated with high
mechanical abrasion/shearing forces
| ex. skin
55
junctional complex is also known as
terminal bar
56
junctional complex
specialized, circumferential intercellular connection
57
junctional complex is a hybrid between
adhering and occluding junctions
58
junctional complex forms a
diffusion barrier between cells
59
threes zones of junctional complexes
```
zonula occludens (tight junction)
zonula adherens (adherent junction)
macula adherens (desmosomes)
```
60
communicating junctions are also known as
gap junctions or nexus junctions
61
what are gap junctions?
focal, or regional adherent zones located on lateral border of cell
62
what are hap junctions formed by?
hundreds of connexions formed by ring of 6 integral proteins called connexions surrounding 2 nm diameter pores
63
what do gap junctions allow for?
passage of small molecules between adjacent cells, allow transport of info and metabolites between cells
64
microvilli
finger-like cytoplasmic projections, extend from the cell surface
65
microvilli contain --- filaments
actin
66
microvilli work to increase
surface area for absorption or secretion
=striated border in intestine
=brush border in renal tubules
67
microvilli are supported by the
terminal web
68
terminal web
network of actin microfilaments at the base of microvilli which provide support
69
stereocillia
long microvilli, not Cilia
70
where are setereocilia found? (2)
epidermis of males
| sensory cells of the inner ear
71
are stereocilia motile?
no
72
stereoilia contain --- filaments
actin
73
cilia
long, motile cytoplasmic extensions
74
cilia posses an
axoneme
75
axoneme
9+2 arrangement of microtiniles
76
each cilium arises from individual
basal body
77
basal body develops from
centrioles
78
cilia beat in what kind of rhythm?
synchronous, metachronal rhythm
79
cilia strokes
| effective vs recovery
rapid, rigid, effective stroke
| slower, flexible recovery stroke
80
what do cilia contain?
microtubule doublets with dynein arms
81
what happens if microtubules lack dynein arms?
ciliary mobility is impaired or absent
82
kartageners syndrome
causes sterility in males due to non functional flagella on sperm
83
dextrocardia (or sinus inversus)
due to absence of ciliary activity during embryonic Development
84
hydrocephalus
due to non functional cilia on ependymal cells unable to circulate CSF
85
what are the 3 criteria for epithelial classification?
```
# of cell layers
shape of cells (at epithelial surface)
surface specializations (cilia, keratin, etc)
```
86
of layers (3)
simple
stratified
pseudostratified
87
simple
1 cell layer thick
88
stratified
two or more cell layers
89
pseudostratified
looks stratified, but isn't
| all cells rest on the basement membrane, but not all cells extend t the epithelial surface
90
shape of cells (3)
squamous
cuboidal
columnar
91
squamous
flattened
| width>height
92
cuboidal
width~=depth~=height
93
columnar
hight>width
94
transitional epithelia (3)
lines most of the urinary tract (except parts of the urethra)
stratified epithelium, modified for distensibility
varies from squamous to cuboidal
95
endothelium
epithelial lining blood vessels and lymphatics; simple squamous
96
mesothelium
epithelium lining closed body cavities
(ex. thoracic, pericardial, and abdominal cavities)
simple squamous
97
glands are composed of epithelial cells, specialized for (2)
synthesis and secretion
98
glands can be classified through (3)
morphology
type of secretory product
mode of discharge of secretory product
99
duct morphology (2)
simple gland
| compound grand
100
simple gland
unbranched cuts (straight or coiled)
101
compound gland
branched ducts
102
shape of gland (3)
tubular
acinar
tubuloacinar
103
tubular
tube-like (straight or coiled)
104
acing/alveolar
sac-like or flat shaped, individual sac called acinus
105
tubuloacinar
intermediate, tube with dilated end
106
type of secretory product (5)
```
serous
mucous
mixed
sebaceous
ceruminois
```
107
serous
water; basophilic acini
| ex. parotid
108
mucous
thick, viscid secretion (mucus); clear on H&E
| ex. palatal
109
mixed (seromucous)
contain both cuboid and serous acini, often include serous demilunes
(ex. submandibular)
110
sebaceous gland of the skin
secrete lipids in the form of sebum
111
ceruminous glands of external ear canal
secrete cerumen (ear wax)
112
two main functional groups
endocrine glands
| exocrine glands
113
endocrine glands
```
lack ducts
secrete products (hormones) directly into the bloodstream
```
114
exocrine glands
secrete product onto epithelial surface via ducts
115
exocrine glands containspecialized contractile cells, called
myoepithelial cells
| li between secretory cells and the BM, assist in secretion
116
goblet cells
specialized, unicellular exocrine glands, located in epithelium, secrete mucous
117
mode of discharge (3)
merocrine
apocrine
holocirine
118
merocrine (eccrine)
only secretory product is released, generally proteins
119
most common mode of discharge
merocrine, involves simple exocytosis
120
apocrine
secrete membrane bound vesicles, product accompanied by some cytoplasm
usually lipid precuts (ex. sweat and mammary glands)
121
holocrine
entire cell secreted (ruptures, released contents)
| ex. sebaceous glands
