EPITHELIUM Flashcards
Tissue: Epithelial
Cells:
Aggregated polyhedral cells
Tissue: Epithelial
ECM amount:
Small amount
Tissue: Epithelial
Main functions:
Lining of surface or body cavities
Glandular secretion
Epithelial Tissue also known as
Epithelium
consists of sheets of cells that:
- cover the external surfaces of the body
- line the internal cavities and the organs
- form various organs and glands and
- line their ducts
EPITHELIAL TISSUE, OR EPITHELIUM
Epithelium = is not supplied by the blood vessels and is therefore _____
nonvascular
separates epithelium from connective tissue
BASEMENT MEMBRANE
TWO FUNCTIONAL TYPES OF EPITHELIUM:
lining epithelium
glandular epithelium
Epithelium: Location
- Esophagus
- Trachea
- Stomach
- Small intestine
Functions of Epithelium (TASP)
Transcellular transport
Absorption (endocytosis or pinocytosis)
Secretion (exocytosis)
Protection from abrasion and injury
Cell polarity (LAB)
Apical domain
Lateral domain
Basal domain
All epithelial cells in contact with subjacent connective tissue have at their basal surfaces a specialized, feltlike sheet of extracellular material referred to as the __________
basement membrane
What can be found in the BASAL DOMAIN
BASEMENT MEMBRANE
What can be found in the LATERAL DOMAIN
INTERCELLULAR ADHESION & JUNCTIONS
5 Junctions
Tight Junction (Zonula Occludens)
Adherens Junction (Zonula Adherens)
Desmosome (Macula Adherens)
Gap Junction (Nexus)
Hemidesmosome
Occludins, claudins, ZO proteins
Actin filaments
Seals adjacent cells to one another, controlling passage of molecules between them; separates apical and basolateral membrane domains
Defects in occludins may compromise the fetal blood-brain barrier, leading to severe neurologic disorders
Tight Junction (Zonula Occludens)
E-cadherin, catenin complexes
Actin filaments
Provides points linking the cytoskeletons of adjacent cells; strengthens and stabilizes nearby tight junctions
Loss of E-cadherin in epithelial cell tumors (carcinomas) promotes tumor invasion and the shift to malignancy
Adherens Junction (Zonula Adherens)
Cadherin family proteins (desmogleins, desmocollin)
Intermediate filaments (keratins)
Provides points of strong intermediate filament coupling between adjacent cells, strengthening the tissue
Autoimmunity against desmoglein I leads to dyshesive skin disorders characterized by reduced cohesion of epidermal cells
Desmosome
(Macula Adherens)
Integrins
Intermediate filaments
Anchors cytoskeleton to the basal lamina
Mutations in the integrin-B4 gene are linked to some types of epidermolysis bullosa, a skin blistering disorder
Hemidesmosome
Connexin
None
Allows direct transfer of small molecules and ions from one cell to another
Mutations in various connexin genes have been linked to certain types of deafness and peripheral neuropathy
Gap Junction (Nexus)
What can be found in the APICAL DOMAIN?
CILIA
MICROVILLA
STEREOCILIA
are motile structures found on certain cells in the uterine tubes, uterus, efferent ducts in the testes, and conducting tubes of the respiratory system.
CILIA
CILIA can be found in
uterine tubes
uterus
efferent ducts in the testes
and conducting tubes of the respiratory system
are small, nonmotile projections that cover the surfaces of all absorptive cells in the small intestine and the proximal convoluted tubules in the kidney
MICROVILLI
