Lecture 2.8 Epithelia Flashcards
What are the types of epithelium, and the functions of epithelium?
- Surface epithelium: lines surfaces and lumina
- Glandular epithelium: predominantly involved in secretion
- Functions of epithelia: protection, barrier, absorption, secretion, receptors
What are the types of simple epithelium?
Squamous - 1 flat layer of cells, in alveoli, glomeruli, mesothelium
Cuboidal - don’t see borders between cells, secretory, thyroid and renal tubules
Columnar - nucleus at base (1/4 -1/3 of space, cancer takes up more)
What is pseudo stratified ciliated columnar epithelium?
One layer that looks like many layers, goblet cells for mucous secretions, present in resp tract
What are the types of stratified epithelium?
Squamous - multiple layers, top layer thin, keratinising
Cuboidal - seen in pancreas and salivary glands (large ducts), two layers
What is urothelium?
Layer of umbrella cells - can expand
What are microvilli and cilia?
Microvilli - 0.5-1um, on brush border on apical surface (lots near each other)
Cilia - apical surface, 2-10nm, resp tract and fallopian tubes, attach to basal body
What are the types of junctions?
Gap: channels (connexons) linking adjacent cells
Adherens: zonular (cadherins to actin), desmosome (intermediate filaments), hemidesmosome (integrins to BM)
Tight: apex of cell, seal intercellular space, made up of caudins and occludens, circumferential in blood brain barrier
What are CAMS?
Cell adhesion molecules, link neighbouring cell or matrix, 4 groups; interns, cadherins, selectins, immunoglobulin superfamily
Where do exocrine and endocrine secrete to?
Exo - epithelial surface or duct
Endo - blood
What are serous acini?
Pancreas and salivary glands - secretion is carried away by duct, basophilic at base and acidophilic at apex
What do myoepithelial cells do?
Have a columnar surface and epithelial base - contract to expel secretions
