Characteristics of all Epithelial Tissues

19 Pages·2009·1.32 MB·English

by  Craig Mandato

Characteristics of all Epithelial Tissues
1. Cells are closely associated with little extracellular space
2. Cells are strongly attached via intracellular junctions
3. Line body surfaces and body cavities
4. Specialization - absorption, secretion,sensation, contractility
5. Cells are polarized
6. Epithelial tissues rest on a basement membrane
Basement Membrane = Basal Lamina
Functions:
1) Structural attachment of epithelial cells to the CT
2) Compartmentalization. Isolate epithelial cells and muscle cells
3) Filtration. Movement of molecules is in part regulated by ionic
charges (particularly important in the kidney)
4) Help to maintain the polarity of the epithelial tissues
5) Tissue scaffolding. Helps to scaffold regeneration
(example: during nerve regeneration)
Composition
Proteoglycans, glycoproteins, collagen. A layer of reticular fibers
underlies basement membranes
Hemidesmosome
Zonula Occludens
Zonula Adherens
Gap Junction
Desmosome
Basement
Hemidesmosome
Membranes
Hemidesmosome
Zonula Occludens
Membrane Proteins:
Occludin, Claudin
Cytoplasmic Proteins:
ZO-1, actin, etc.

Zonula Adherens
α - actinin, vinculin
Intercellular Space
Actin (15 nm)
Cadherins
DESMOSOME (MACULA ADHERENS)
Desmoplakins I and II,
Plakoglobin, Desmocalmin
Intercellular Space
(25 nm)
Contains the
Transmembrane
Intermediate
Proteins Desmocollin
Filaments
and
Desmoglein
HEMIDESMOSOME
Plaque Contains
Tonofilaments
BP 200
Plaque
TM Contains
PM
Transmembrane
TM
Proteins α6 Integrin, BM
β4 Integrin
and BP 180
Type VII Collagen
The Term BP
is related to
Bullous Phemphigoid