This Topic is all about Epithelium

1. Microscopic Examination
and Identification of
DifferentTypes of Epithelia

2. Tissues
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4. In multicellular organisms, cells integrate
themselves in a social context with other
cells
assume specialized roles with functions
that benefit the entire organism
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5. Tissues = groups of cells that are similar
in structure and function.
Epithelium
Coverings
Linings of
surfaces
Connective
Support
Bone, ligaments,
fat, blood
Muscle
Movement
Nervous
Control
Brain, nerves,
spinal cord
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6. Epithelia (plural)
sheet of cells that covers a body surface or lines a
body cavity; also form most of the body’s glands
Reside on the basement membrane
Roles: as interfaces and as boundaries
Functions:
Protection Absorption
Sensory reception Ion transport
Secretion Filtration
Formation of slippery surfaces for movement
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8. Special characteristics of epithelia
Cellularity
Specialized contacts
Polarity
Free upper (apical) surface
Lower (basal) surface contributing basal lamina to basement
membrane
Support by connective tissue
Avascular but innervated
Without vessels
With nerve endings
Regeneration
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9. Classification of epithelia
According to thickness
“simple” - one cell layer
“stratified” – more than one layer of cells (which
are named according to the shape of the cells in
the apical layer)
According to shape
“squamous” – wider than tall
“cuboidal” – as tall as wide
“columnar” - taller than wide
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11. to protect
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12. where diffusion is important
where tissues are involved in
secretion and absorption:
larger cells because of the
machinery of production,
packaging, and energy
requirements
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13. • Classification is based on the number of cell layers
and the morphology or structure of the surface cells
• A basement membrane is a thin, noncellular region
that separates the epithelium from the underlying
connective tissue and is easily seen with a light
microscope
• An epithelium with a single layer of cells is called
simple, and that with numerous cell layers is called
stratified
• A pseudostratifed epithelium consists of a single
layer of cells that attaches to a basement
membrane, but not all cells reach the surface.
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“ciliated” literally = eyelashes
(see next page)
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Stratified: regenerate from below
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Rare…
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23. Rare…
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25. Endothelium
A simple squamous epithelium that lines the
interior of the circulatory vessels and heart
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26. Mesothelium
Simple squamous epithelium that lines the
peritoneal, pleural and pericardial cavities and
covers the viscera
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谢谢你的

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