Epithelium Flashcards
What are the functions of epithelium?
1) PROTECTION of the underlying tissue from trauma
2) SECRETION: mucus, enzymes, hormones
3) ABSORPTION ( via endocytosis/pinocytosis) substances from lumen, eg intestine & kidney
4) TRANSPORT OF MATERIAL ON THE EPITHELIAL SURFACE (cilia) and TRANSCELLULAR TRANSPORT across epithelium (diffusion & vesicle mediated)
5) SELECTIVE PERMEABILITY of intercellular junction
6) SENSORY CELLS: taste bud, retina & hair cells in ear
Define simple epithelia
All cells contact the basement membrane and all cells reach the free surface
Define pseudostratified epithelia
All cells touch basement membrane but not all reach the free surface
Define stratified epithelia
Only basal layer of cells touch basement membrane, not all cells reach free surface
Define transitional epithelia
Type of stratified epithelia where the surface cells change between squamous and cuboidal shapes
Function of simple squamous epithelium
Involved in passive transport (diffusion) of gasses or fluids
Types of simple squamous epithelium
Endothelium
Mesothelium
Functions of simple cuboidal epithelium
Excrete, secrete, or absorb
Where can simple cuboidal epithelium be found?
Lining the small ducts and tubules, e.g. ducts of salivary glands and pancreas; collecting tubules of kidney
Where are simple columnar epithelium found?
Absorptive surfaces such as in the small intestine (with microvilli)
“Strongest protection against abrasion (not to dryness)” describes what kind of epithelium?
Non-keratinized stratified squamous
Where is non-keratinized stratified squamous found?
Oral cavity, pharynx, esophagus, anal canal, vagina, cervix
Mucus producing glands are associated with what kind of epithelium?
Non- keratinized stratified squamous
The only keratinized type of stratified squamous epithelium is the _______
Epidermis
Function of keratinized stratified squamous
Protects against abrasion
Where is stratified cuboidal epithelium found?
Lining the ducts of sweat glands in skin
What is the function of stratified columnar epithelium?
Just to provide lining of ducts
Where is stratified columnar epithelium found?
Lining of larger excretory ducts of exocrine glands, such as the salivary glands
Where is pseudostratified (columnar) epithelium found?
Respiratory tract