Unformatted text preview: a ﬂap/propeller! Fig. 4-11 The axoneme is
organized by the basal
body which resembles
a centriole, having 9
MT triplets and none in
the center. tons of ATP in these cells, so lots of mitochondria -- way more than wimpy microvilli. Epithelia are classified and named histologically based on the
number of cell layers (simple vs. stratified) and cell shape.
Simple squamous epithelium Simple cuboidal epithelium
THIN Figs. 4-12 & 13 Simple columnar epithelium
ARE WIDE! Fig. 4-14 (trachea!!!) Pseudostratified epithelium
Diff cell types
w/ nuclei @
diff levels -APPEARS
not really! Fig. 4-17 Tall epithelium cells can be simple (usually
specialized for absorption or secretion) or
“pseudostratified” (nuclei not aligned).
Pseudostratified epithelia usually include
cells with cilia and are found mainly in the
lining of the respiratory tract. Stratified epithelia have 2 or more cell layers on the basement membrane and are
named according to the shape of the surface cells. The most common, stratified
squamous epithelium, may have the surface cells keratinized (a) with the nuclei lost,
(in the case of EPIDERMIS)
or “nonkeratinized” (b, c).
A bunch of diff layers!!! As you move up from
basement membrane, they start to get FLATTER
and thus more SQUAMOUS. Fig. 4-15 stratified
epithelium Another specialized epithelial type is transitional epithelium or urothelium , which is
found only in the lining of the urinary bladder and ureters. It is protective and “stretches”
as the bladder fills. (Discussed later with the urinary system.)
Protective against urine! Fig. 4-16...
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- Spring '14
- Epithelial cells, Epithelia, basement membrane