2. Epithelia Flashcards
What is epithelia?
A cohesive sheet of cells with one or more layers resting on a basement membrane
What are epithelia barriers formed for?
Protection, absorption and secretion
How are epithelia categorised?
Shape of cells, number of layers of cells
What is simple epithelia?
Single layer of cells on a basement membrane
What is stratified epithelia?
Two or more layers of cells on basement membrane
Describe simple squamous epithelia.
Single layer of flattened, plate-like cells on a basement membrane
Describe simple cuboidal epithelia.
Single layer of cells with similar height and width on a basement membrane
Describe simple columnar epithelia.
Single layer of cells taller than they are wide on a basement membrane
What are microvilli?
Microscopic projections on luminal surface of absorptive cells that increase surface area
What are cilia?
Microscopic motile projections on luminal surface of cells
Describe the features of stratified epithelia.
Protective function
Many layers of cells
Continually being worn down/worn-away cells replaced from below
Stem cells lie in basal layer
Describe stratified squamous non-keritanising epithelia.
Multiple layer of cells on a basement membrane
Mature surface layers are plate-like squames
Describe stratified squamous keritanising epithelia.
Multiple layer of cells on a basement membrane
Mature surface layers are plate-like squames
Waterproof layer of keratin
Describe pseudostratified epithelia.
Single layer of cells of variable height, mimicking multiple layers on a basement membrane
All cells in contact with basement membrane
Describe urothelium.
Looks stratified and probably is BUT…
Surface layer of umbrella cells. Waterproof.
