Epithelium Flashcards
What are the two types of epithelium?
Surface epithelium and glandular epithelium
What are the functions of epithelium?
Protection, secretion, receptors, absorption, barrier
What are the characteristics of epithelium?
Polar (different domains), avascular, cells are connected by cell junctions, has a basement membrane
What are the different classifications of surface epithelium?
simple squamous, simple columnar, simple cuboidal, pseudostratified ciliated columnar, stratified squamous, stratified cuboidal, transitional
What does simple squamous epithelium look like?
One layer of flat cells
Where is simple squamous epithelium found?
mesothelium (lining of body cavity), endothelium (lining of heart), lining of alveoli, glomeruli
What does simple cuboidal epithelium look like?
One layer of cube like cells
Where is simple cuboidal epithelium found?
thyroid follicles, renal tubules
What does simple columnar epithelium look like?
One layer of tall (columnar) cells - can either be ciliated or non ciliated
Where is simple columnar epithelium found?
Non ciliated in stomach, intestines, gall bladder, bile ducts, endometrium, endocervix and ciliated in fallopian tubes and bronchioles
What does pseudostratified ciliated columnar epithelium look like?
It looks stratified but is actually simple (only one cell layer) because the cells are so long - but really each cell touches the basement membrane
Where is pseudostratified ciliated columnar epithelium found?
In the respiratory tract - non ciliated is found in the vas deferens and the epididymus
What does stratified squamous epithelium look like?
Only the top layer of cells are actually squamous cells - there are then several layers of cells down to the basement membrane - there are two types keratinising and non keratinising
Where is stratified squamous epithelium found?
keratinising is found in the skin, non keratinising is found in the oral cavity, oesophagus, vagina, ectocervix, anus
What does stratified cuboidal epithelium look like?
It is two layers of cuboidal cells
Where is stratified cuboidal epithelium found?
In ducts
What does transitional epithelium look like?
It is stratified epithelium that looks either squamous or cuboidal depending on whether it is stretched or not
Where is transitional epithelium found?
renal pelvis, ureters, bladder
What is microvilli?
Tiny extensions of the apical surface on epithelial cells - to increase surface area
What are cilia?
Long projections on the apical surface of some epithelium - contains microtubules - for movement
What are the different kinds of intercellular junctions in epithelium?
tight junctions, adhering junctions (desmosomes) and gap junctions
What is the purpose of tight junctions?
Tight junctions seals of intercellular spaces so that nothing can get through
What is the purpose of adhering junctions?
To link cytoskeleton between cells - resists shearing forces
What is the purpose of gap junctions?
To allow communication between cells
What are cell adhesion molecules (CAMS)?
Transmembrane proteins that link with CAMS on neighbouring cells
What are the four different types of CAMS?
Caherins, integrins, selectins, immunoglobulin superfamily
What is mucosa?
Surface epithelium and underlying supportive connective tissue
What is serosa?
Surface mesothelium and underlying supportive connective tissue
What is erosion?
Defect in surface eptihelium
What is an ulcer?
Local defect in mucosa
What are goblet cells?
Mucus secreting single cell glandular epithelium that has an exocrine function
What is serous acini?
A secretory unit of serous cells
What are myoepithelial cells?
Contractile cells that surround glands
What are the 3 components of cytoskeleton?
microfilaments, intermediate filaments, microtubules
