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
What is the role of the basal membrane?
Separates the epithelium from the underlying connective tissue
How may the basal membrane appear?
It may be folded
What are the two layers of the basal membrane called?
Basal lamina
Reticular lamina
What are the two layers of the basal lamina called?
The lamina lucida
The lamina densa
What is the lamina lucida also called?
Clear layer
What is the lamina densa also called?
Dense layer
Give three points on the lamina lucida/clear layer.
Thin
Secreted by epithelia
Barrier to CT proteins
Give three points on the lamina densa/dense layer
Thick fibers
Produced by connective tissue
Strength and filtration
What produces the lamina lucida/clear layer?
They are secreted by epithelia
What produces the lamina densa?
It is produced by connective tissue
Where are stem cells found?
Stem cells are found in the basal layer of stratified epithelia
What makes up epithelial tissue?
Epithelial cells that are attached along their sides
