Epithelial Tissues Flashcards
what are epithelial tissues
line all surfaces
what is the main function of epithelial tissue
barrier function - continuous boundary between different environments
how are epithelia arranged
continuous sheet of tightly bound cells
what does polarised mean
all the apex surfaces of the cells point towards the external surface (lumen)
what are tight junctions
create an impermeable seal between adjacent cells
what are desmosomes
anchor adjacent cells together and can ensure cells can stretch without being pulled apart
name four additional functions of epithelial tissue apart form barrier
protection
diffusion
absorption
secretion
what are the three components of classification for epithelial tissues
shape
number of cell layers
apical speicalisation
what are the three types of epithelial cells
squamous
cuboidal
columnar
what are the two classifications of cell layers of epithelium
simple
stratified
what are pseudostratified epithelium
look columnar book nuclei are all at different heights - appears as multiple layers but only have one layer
what is transitional epithelia
more than two cell layers but the cells in the tissue do not conform to just one shape - good for stretching
what are examples of apical specialisations in epithelial cells
microvilli
cilia
keratin
what is the function of simple squamous epithelia
passive diffusion
what is the function of simple cuboidal epithelia
small ducts involved in absorption or secretion
what is the function of simple columnar epithelia
absorptive surfaces and can sometimes find microvilli
what is the function of cilia
to help substances move down the tissue - eg in the ovaries
what are goblet cells
modified columnar epithelial cells that synthesise and secrete mucous
what is the function of stratified cuboidal and columnar epithelia
secretion
what is the function of stratified squamous epithelia
protection from mechanical abrasion
how does shedding of skin cells (stratified squamous) work
cells are cuboidal at the bottom, they are flattened as the cells get pushed to the top and they die and shed
where is transitional epithelium found
bladder
what is ulceration
break in the continuity of the epithelium
what histological features can be seen in dysplastic epithelial cells
they degrade the basement membrane so they can spread to underlying connective tissues
