Histology 2 Flashcards
What does the epithelia do?
Forms barriers for protection, absorption and secretion
What is the epithelia?
Cohesive sheets of cells, with one or more layers, resting on a basement membrane.
Where are epithelia found?
‘ On the edges of us’ etc surface of our skin, lining of our mouth, lining of our gut
What are the 7 types of epithelium?
Simple squamous
Simple cuboidal
Simple columnar
Microvilli and cilia
Stratified epithelia
Pseudo-stratified epithelia
Cell junctions
What is simple epithelia?
Single layer of cells on a
basement membrane
What is stratified (compound) epithelia?
Two or more layers of cells on
a basement membrane
What is simple squamous epithelium?
Single layer of flattened plate-like cells on a basement membrane
Where are Simple squamous epithelium found?
Lines inside of blood vessels (endothelium)
Outside of lungs (mesothelium)
Abdominal organs (peritoneum)
What is the simple cuboidal epithelium?
Single layer of cells with similar height and width on a basement membrane
Where is simple cuboidal epithelium found?
Line kidney tubules
Small ducts
What is the simple columnar epithelium?
Single layer of cells taller than they are wide, on a basement membrane
Where is simple columnar epithelium found?
Line the stomach
Intestines
Uterus
What is microvilli?
Microscopic projections on luminal surface of absorptive cells
What is the purpose of microvilli?
Increase surface area
Intestinal brush border
What is the cilia?
Microscopic motile projections on luminal surface of cells
Where are cilia found?
Respiratory tract
Reproductive tract
What are features of the stratified epithelia?
Protective function
Many layers of cells
Continually being worn down
Worn-away cells replaced from below
What are the locations of stratified epithelia?
Found at sites subject to abrasive forces
What is the stratified squamous non-keratinising epithelium?
Multiple layer of cells on a basement membrane
Where are stratified squamous non-keratinising epithelium found?
Lines the mouth, oropharynx, oesophagus, vagina
What are stratified squamous keratinising epithelium?
Multiple layer of cells on a basement membrane
Where are stratified squamous keratinising epithelium?
Skin
What is the pseudostratified epithelium?
Single layer of cells of variable height, mimicking multiple layers on a basement membrane
Where are pseudostratified epithelium found?
Lines the conducting airways
What is urothelium?
Specialised stratified epithelium
Breaks the rules – looks stratified, probably is stratified, but: Surface layer of umbrella cells
What is the basement membrane?
Composed of several extra-cellular proteins including Collagen IV and Fibronectin
Why is the basement membrane important?
Essential for the proper functioning and survival of the epithelium
With what stain can base membrane be seen?
PAS
What are epithelial junctions (occluding, tight junctions)?
Band-like fusions between cells that are impervious to most molecules
Prevent diffusion between cells
What are epithelial junctions (desmosomes)?
Plaques that form physical joins between cells and connect the cytoskeletons of adjacent cells
Spread forces across several cells
What are epithelial junctions Gap (aka communicating) junctions?
Electrical junctions that permit the transfer of small molecules
Electrically couple adjacent cells
Which two proteins are principally involved in the generation of ciliary movement?
Tubulin and Dynein
A gland secretes by shedding individual cells.
What type of secretion is this?
Holocrine
What are hemidesmosomes?
Multiprotein complex that facilitates adhesion of basal epithelial cells to underlying basement membrane
