Epithelial Tissue Histology Flashcards
What is the function of epithelial tissue?
Cover and line the internal and external body surfaces
What two layers are below epithelial cells?
Basal Lamina
Extra cellular matrix
What is above the apical surface on epithelial cells?
Free surface
Do epithelial cells have connective tissue between cells?
No, they are completely acellular
What are the three types of cell junction for integrity?
Occluding (barrier)
Anchoring (strength)
Communicating (movement between cells)
What are the cell junctions for occluding junctions? (Barrier)
Tight junctions
What are the cell junctions for anchoring junctions? (Strength)
Desmosomes between cells
Hemidesmosomes between basal surface and basal lamina
Rete pegs (stratified squamous epithelium only) between basal surface and basal lamina
Why is epithelium tissue avascular?
Blood vessels only in connective tissue
No connective tissue in epithelia
Epithelial cells are regenerating. What feature allows them to do this?
High rate of cell division
What is underlying the basal lamina? What is it’s purpose?
Connective tissue
Metabolic and mechanical metabolism
What are the two main categories of epithelial tissue?
Simple
Stratified
What are the types of simple epithelium?
Simple squamous
Simple cuboidal
Simple columnar
Simple pseudostratified
Where is simple squamous epithelium found?
Alveoli
Lining blood vessels (called endothelium)
Where is simple cuboidal epithelium found? Does simple cuboidal synthesise any products? What is the purpose of simple cuboidal epithelium?
Lining ducts
No synthesis except in thyroid gland
Structural support
Where are simple columnar cells found? Which other cells are found here and what do they produce? What do some types of columnar cell have on their apical surface?
Gut
Goblet cells, producing mucous
Some have microvilli for large SA, some have cilia for movement
Apart from simple cuboidal, columnar and squamous, what is the other type of simple epithelium?
Simple pseudostratified (falsely layered) All basal surfaces attached to basal lamina
What are the two types of stratified epithelium?
Stratified squamous
Stratified transitional
Where is stratified squamous epithelium found? Why is this type of epithelium suitable?
Anywhere that needs defence against mechanical damage e.g. foot pads, skin, inside mouth/trachea
Constantly replaces as cells divide in lower layers and move to the top.
What are the two types of stratified squamous epithelium?
Keratinised
Parakeratonic
What does keratinised stratified squamous epithelium contain on the apical surface?
Pure keratin on top
Keratohyalin below which gives rise to keratin
Where is parakeratotic epithelium found? What is it’s function?
Ruminant fore stomach only
Absorbs volatile fatty acids
Where is transitional stratified epithelium found? What does it do?
Bladder/urinary system
Stretches (appears like stratified squamous in microscope)
