Epithelium Gland
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Transcript of Epithelium Gland
8/7/2019 Epithelium Gland
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General
� Tissues - groups of cells with similar basic structureswhich cooperate to perform a related function
� Four basic types of tissues± Epithelial linings for protection, coordination, synthesis,
absorption, elimination
± Connective support
± Muscle for movement� muscle tissue is a highly specialized connective tissue
± Nervous for control and coordination� nervous tissue is a highly specialized epithelial tissue
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Epithelial Tissue Characteristics
1. Cellularity - densely packed
2. Polarity� apical surface
� basal surface (or basolateral)
3. Specialized contacts - tight junctions anddesmosomes
4. Supported by connective tissue� basal lamina (epithelial glue)
� reticular lamina (connective tissue glue)
� basement membrane - reticular and basal laminae together
5. Innervated but avascular (no direct blood supply)
6. Regeneration high capacity for regeneration
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Simple
Stratified
Classifying Epithelial Tissues
� B
ynu
mber of cell layers
Pseudostratified epithelium (from the respiratory
tree) appears stratified, but actually is a single
layer of cells of varying heights; each cell touches
the basement membrane
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Classifying Epithelial Tissues
± By cell shape
Transitional
Squamous
Columnar
Cuboidal
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Glandular Epithelial Tissues
� functions in secretion a gland may be one cellor a group of specialized cells
� two major types±
exocrine glands have ducts leading to body surfaces� various products are synthesized and stored for release
� secretions are secreted into the duct system
� e.g., sweat glands, salivary glands, etc.
± endocrine glands are ductless� hormones are synthesized and stored for release� hormones are secreted into the tissue fluid and then diffuse
into the blood stream
� e.g., thyroid and parathyroid glands
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Exocrine Gland Classification
� Unicellular glands
± single cell glands
� goblet cells
� neuroendocrine cells
goblet cell
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Exocrine Gland Classification� Multicellular glands
± Structurally classified byduct configuration and
by the shape of the
secretory units
� simple glands have a
single duct
� compound glands have
branched ducts
± Merocrine glands
� Exocytosis
± Holocrine glands
� Cell rupture
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Types of Glands
Exocrine: all glands with ducts
Endocrine: ductless glands (hormones)
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Apocrine Glands
� top of cell pinches off releasing contents
� some sweat glands (armpits and groin)
�
cause scent when fatty acids and proteins insweat metabolize
� become active at puberty
� Why do guys smell worse?
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Merocrine Glands
Merocrine (eccrine): secretion by exocytosis
� Salivary glands and sweat glands (temp reg)
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Holocrine Glands
Holocrine: cell ruptures releasing contents
� sebaceous glands
� sebum
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Sweat Facts
The average person had 2.6 million sweat
glands in their integument.
There are sweat glands distributed over the
entire body---except the lips, nipples, and
external genitalia.
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MucousMembranes
Mucous
± Line cavities open to exterior (nose, mouth, etc)
±
Often secrete mucous
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Serous Membranes
Occur in pairs
»Visceral: lines organs
»Parietal: lines body cavities
used to avoid friction
lines cavities closed to exterior
secrete serous fluid lubricant