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Epithelia
8/23/11 First Lecture
12
Medical
Graduate
08/23/2011

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Cards

Term
What three morphological characteristics are epithelia classified by
Definition
1. Number of cell layers
2. Shape
3. presence of surface specializations
Term
What are the 3 functions of simple epithelia
Definition
1. Selective diffusion
2. absorption
3. secretion
Term
What are the two types of epithelia based on number of cell layers present
Definition
1. Simple - 1 cell layer
2. Stratified - 2+ cell layers
Term
What are the 3 types of epithelia based on shape and their characteristics
Definition
1. Squamous - flattened, irregular shape, form continuous lining, selective diffusion
2. Cuboidal - square, usually secrete or absorb
3. Columnar - taller then they are wide, usually absorb
Term
What are the 4 types of stratified epithelia
Definition
1. stratified squamous - line most tissues subjected to abrasion
2. stratified squamous keratinized - resist abrasion and desiccation, dead outer layer of cells (anucleated)
3. Stratified cuboidal - provide robust lining
4. Transitional - withstand stretch and toxicity of urine
Term
What do cilia do and how do they work
Definition
They propel fluid, have microtubules inside that use proteins (dynein) to make them move.
Term
What do microvilli do and how do they work
Definition
They are membrane projections that increase surface area for pumps or other transporters and allow additional absorption and secretion
Term
What are stereocilia
Definition
Non motile structures in the epididymis that facilitate absorption.
Term
What are the two major roles of tight junctions
Definition
1. Fence - separate the proteins on the basolateral side from those on the apical side
2. Regulate the movement of solutes between cells
Term
What molecules form gap junctions and what purpose do they serve
Definition
Proteins called connexins combine for form connexons which allow cell-cell communication
Term
What molecules form the connections in adherens junctions
Definition
Cadherins
Term
What 2 major benefits do desmosomes and hemidesmosomes provide to cells
Definition
1. Dispersion of force - increases cell strength and integrity
2. Mechanochemical signaling - Allows cells to sense and react to mechanical stress
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