Covering Epithelia Flashcards
What are some components of epithelia
Composed of closely aggregated polyhedral epithelial cells with a minimum of intracellular substance
Adhesion between cells is strong thus cellular sheets formed which are able to cover exposed external surface and line internal cavities
What are the three embryo logical germ layers
Ectoderm - gives rise to epithelia of skin and its associated glands and the oral, nasal and anal passages
Mesoderm - gives rise to epithelia linings of cv system and to the mesothelioma lining perineum
Endoderm - gives rise to epithelia of the gut, RESP tract, liver and epithelia glands associated with the gut
What are some common features of epithelia
Basal surface - sheet like structure composed of extracellular matrix components called a basal lamina
Non-vascular
Usually polarised
Bind in sheets
What are the functions of epithelia
Mechanical barrier Chemical barrier Absorption Secretion Containment Locomotion Minor functions such as sensation
What are the three main classes of filaments
Micro filaments
Intermediate
Microtubules
What are the microfilamemts composed of
Actin
Anchor movement and extension of cell
What are microtubules composed of
Tubulin subunit alpha and beta
Originate from centre some
What are 3 types of intercellular junctions
Occluding - link cells to form diffusion barrier
Anchoring - provide mechanical strength
Communicating - allow movement of molecules between cells
What are occluding junctions
Prevent diffusion
From ring like band
Itight junctions or zonula occludens
What are anchoring junctions
Link submembrane actin bundles of adjacent cells
Zonula adherens
Transmembrane cadherins mols bind to each other in extracellular space and link to actin
Desmosomes
Hemidesmosomes
Junctionsk complex
What are communicating junctions
Allow selective diff of small mols
Gap junctions
Pores produced by connexon PROETINS
How is covering epithelia classified
Cell shape
Number of layers of cells
Cell surface specialisations
Presence of any specialised cell types
What are the different cell shapes
Squamous
Cuboidal
Columnar
What are the number of layers that can happen
Simple
Stratified
Pseudo stratified
What are some cell surface specialisations
Prominent Microvilli
Cilia
Keratinised
