Epithelia Flashcards
What main functions do epithelia help with?
Diffusion
Protection
Secretion
Absorption
What is the reticular lamina?
Reticular fibres anchoring the basement membrane to underlying connective tissue (usually collagen or elastin)
How is cell communication between epithelial cells maintained?
Lateral communication through gap junctions of water, ions and small molecules
How are epithelial cells joined together and to the basement membrane?
Cell matrix attachments bond epithelial cells to tissue beneath
Stress bearing cytoskeletons linked from cell to cell by adhesive junctions
Adhering junctions form belt around cells linked to bundles of actin fibres
Myosin filaments can pull on cells to contract
What are epithelial-mesenchymal interactions? What is their purpose?
Epithelium is in close contact with underlying mesenchyme
controls epithelial cell fate via switched expression of cadherins
important in embryonic development
What are the two main types of epithelial tissue? What are the others that don’t fit into these?
Stratified- many layers
Simple- single layer
Psuedostratified and transitional
Features of simple squamous epithelia
Appearance of thin scales
Facilitates rapid passage of molecules
What is the function of simple cuboidal epithelia? Where are they found?
Secretion and absorption of substances requiring active transport
kidney tubules and ducts of glands
What is the function of simple columnar epithelia? Where are they found?
Can be with or without cillia/microvilli
Absorption and secretion of molecules requiring AT
Majority of GI tract, fallopian tubes, parts of respiratory system
What are the features of pseudostratified columnar epithelia?
Single layer of cells but with the appearance of multiple layers due to the nuclei being at different levels, but all are in touch with the basement membrane
Some don’t reach apical surface
Can be ciliated or unciliated
Stratified squamous epithelia
Most common type of stratified epithelia in the body
Apical cells appear squamous, basal cells appear columnal or cuboidal
Areas of high abrasion
Stratified cuboidal epithelia
Less common
Found in glands
Stratified colmnar epithelia
Rare
Found in conjunctiva, pharynx, anus, male urethra and embryo
Allows tissue to stretch and contract
Transitional epithelia
Cells have round shape when relaxed
Allows change in shape in distension without damaging epithelial lining
