2 - Epithelial Cells II Flashcards
How do epithelial cells make continuous cohesive layers?
they have organised stable cell-cell junctions
Give the order of layers in epithelial organs
Layer of epithelial on the basal lamina
underneath the basal lamina is the interstitial connective fluid and ECM
What are the two main criteria of epithelial classification?
SHAPE: - squamous (flattened) - cuboidal - columnar LAYERING: - simple - stratified
What are the 2 types of stratified squamous epithelia?
Give examples of where they are found in the body
(layers of flat epithelial cells)
(NOTE: have a variety of shapes: quite cuboidal near the surface and quite flat near the surface - surface cells are used for the description)
TWO MAIN TYPES:
- keratinsing: nuclei not visible in the surface cells
dead cells
made very tough by the production of several keratin and proteins and lipids (dry epithelium)
e.g. epidermis (skin)
- non-keratinsing: nuclei are visible in surface in surface layer cells (wet epithelium)
e.g. lining of the mouth
What is meant by pseudostratified columnar epithelium?
there appear to be 2 layers of cells but on further investigation, the cells are attached to the basal lamina
Which surface of the epithelia is attached to the basal lamina and which
apical surface - free surface in contact with the outside/lumen
basal surface - in contact with the matrix
What happens to the ion pumping cells in the kidney if ATP production is inhibited?
the apical part of the cell swells because this is where passive transport of sodium and water into the cell takes place but is not matched by the active transport out at the basal surface
The pancreas has both exocrine and endocrine functions. What is the direction of secretion for both of these?
EXOCRINE - basal —> apical (—> into duct)
ENDOCRINE - apical —> basal (—> into circulation)
What is the order of organelles in a secretory cell?
granular ER and nucleus
golgi apparatus
secretory granules (closest to the surface at which they are going to be secreted)
How can secretory cells be classified?
CONSTITUTIVE - as secretory cells are formed, they move directly to the plasma membrane and release their contents
STIMULATED - secretory vesicles are stored in the cytoplasm and only fuse with the plasma membrane to release their contents when they are stimulated
What are the types of epithelial in protective epithelia?
stratified squamous (keratinising and non-keratinising)
What are the 3 layers of the skin?
epidermis - keratinising
dermis
hypodermis
the cells go through a programme of differentiation as they move up towards the surface
What do defects in cytokeratins or cell-cell junctions lead to?
blistering diseases as a result of epidermal damage
e.g. Epidermolysis Bullosa
Absorptive epithelia has _____ border
striated
