Epithelia - Lateral Surface Specialisations Flashcards
How are epithelial cell specialised to join together?
Epithelial cells have junctional specialisations
What makes up the junctional specialisations of epithelial cells?
Cell membrane proteins and lipids
What are the three types of junctional specialisations?
3
Tight junctions
Gap junctions
Anchoring junctions
What is another name for tight junctions?
Occluding junctions
Where are occluding junctions located?
Between two plasma membranes
Write a note on occluding/tight junctions.
3
Adhesion belt attaches to terminal web
Prevents passage of water and solutes
Isolates wastes in the lumen
What does a tight junction prevent the passage of?
2
Water
Solutes
What does a tight junction do with wastes?
They are isolated in the lumen
What does a tight junction isolate in the lumen?
Wastes
What is the role of gap junctions?
They allow for rapid communication
Write a note on gap junctions
They are held together by channel proteins (junctional proteins, connexons)
Allow ions to pass so cells can communicate
Allow the coordination of cilia beating
What hold gap junctions together?
Channel proteins
Name two channel proteins that hold together gap junctions.
Junctional proteins
Connexons
What passes through gap junctions?
Ions
Why do gap junctions allow ions to pass through?
So cells can communicate
What are desmosomes composed of?
3
Cell adhesion molecules
Dense areas
Intracellular cement
How many types of desmosomes are there?
Two
Name the two types of desmosomes.
Spot desmosomes
Hemidesmosomes
What are the two roles of spot desmosomes?
Tie cells together
Allow bending and twisting
What is the role of hemidesmosomes?
Attach cells to the basal lamina
What is the role of desmosomes?
They attach cells together or to extracellular material
What is the role of the basal surface?
It attaches epithelial cell to extracellular matrix adhesion molecules
What is found beneath the basal surface?
A network of protein and carbohydrate fibres is found beneath the basal surface
What forms the basal membrane?
Epithelial cells and underlying connective tissue