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18 terms

Epithelial tissue

General characteristics, classification, accessories
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Tightly packed cells
- form protective barriers and linings
-cover body and organ surgaces, line body and lumens
-Always has an apical(open) surface
Basement Membrane
Underlying tissues that connects to nourishment supply
- only in ET, thinnest layer
Avascular
without a blood supply of its own
Rapidly Reproduce
-Mitotic cells found at basement membrane level
-Areas where wounds or losses can be closed/replaced quickly
Tight junctions
two cell membranes fuse together
Desmosomes
membranes joined together by glue-like material
Microvilli
Increased surface area for increased absorption, digestive tract
Cilia
Help move liquids etc, over the surface of tissue, respiratory tract (trachea)
Classification of E.T.
- # of layers of cells
- Simple(one), Stratified (multi), Pseudo (fake layers)
Classification of E.T. cont
-Shapes of cells
- Squamous (thin, flat with a central nucleus)
- Cuboidal ( cube-shaped with a central nucleus)
- Columnar (shoe boxed shaped, nucleus near basement membrane)
Simple Squamous ET
-single layer of flat cells tightly packed together
-founds in regions of diffision or filtration
- lungs(alveoli), blood vessels(capillary walls)
Stratified Squamous ET
- many layers of columnar or cuboidal at one end of tissue
- thinner and flatter as pushed to free surface of membrane
- found in areas of abrasion or friction
- skin stratified cells become keratinized
- linings of mouth and oral cavity
Transitional ET
- Several layers of cells that change shape
- Lining of bladder
- allows for expansion
Simple Cuboidal ET
- single layer of cubed shaped cells
-found in secreting glands - kidney tubules, ducts, outer ovary linings
Simple Columnar ET
- single layer of shoe boxed shaped cells
- nuclei at all the same level close to basement membrane
- found in areas of secretion and absorption
- microvilli and goblet cells present
Pseudo- Stratified Columnar ET
- nuclei all over, looks like several layers
- often has cilia
- found in some glands, ducts, trachea, male urethra
Serous Membranes
-line body cavities that dont open to outside, covers organs
- thin layer of simple squamous c thin layer of CT
- secrete watery fluid - lubricates membrane surface
Mucous Membranes
- line cavities that open to the outside
- layer of varying types of ET with a layer of CT