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List the four functions of epithelia
-Produce specialized secretions
Epithelial cells that produce secretions are called ___ and make up ___ epithelium
Gland cells; glandular
Individual epithelial cells may be specialized for which 3 functions?
1) The movement of fluids over the epithelial surface for protection and lubrication
2) The movement of fluids throught the epithelium to control permeability
3) The production of secretions that provide physical protection or act as chemical messengers
List the characteristics of epithelia
1) Cellularity- cells are bound together by cell junctions
2) Polarity- has an exposed (apical) surface and a basal surface.
3) Attachment to a pasal lamina
4) Epithelia are avascular
5) Epithelial cells are capable of rapid regeneration
Epithelial cells are often divided into two function regions called the:
Apical surface and the basolateral surface
Microvilli are especially abundant on epithelial surfaces where ___ and ___ take place.
Absorption and Secretion
To be effective as a barrier, an epithelium must form a complete cover or lining. List three factos that help maintain the physical integrity of an epithelium
1) intercellular connections
2) attachment to the basal lamina
3) epithelial maintenance and repair
Cell junctions are:
Specialized areas of the plasma membrane that attach a cell to another cell or to extracurricular materials.
Three common types of cell junctions are
1) occluding (tight) juctions
2) gap junctions
3) macula adherens
The occluding (tight) junction functions to
prevent the passage of water and solutes between the cells and isolate the contents of lumen from the basolateral surfaces.
Gap Junctions are common among epithelial cells where
the movement of ions helps coordinate functions.
Macula adherens (desmosome) are found in locations subject to mechanical stress because
they are strong and can resist stretching and twisting
The two type of macula adherens are
Spot desmosomes ( connected to bands of intermediate filaments) and hemidesmosomes (attaches a cell to extracellular filaments in the basal lamina.
Lamina Lucida is:
the superficial, clear lay of the basal lamina
Lamina lucida acts as:
a barrier that restricts the movement of proteins and other large molcues from the underlying connective tissue
The dense layer is:
the deep layer of the basal lamina
The dense layer functions to:
give strength to the basement membrane.
Germinative (stem cells) are mostly located
near the basal lamina
Epithelial cells and functions and connective cells and functions