Surface Epithelium Flashcards
does epithelium have blood vessels?
no its avascular
what separates epithelium tissue and vascular tissue?
the basement membrane
what type of epithelium lines the inner body cavity?
mesothelium
what lines the inner surfaces of the blood and lymph vessels
endothelium
type of epithelium lining blood vessels, lymph vessels and heart
simple squamous
type of epithelium in the excretory ducts of glands, thyroid, kidney tubules, ovaries
simple cuboidal
type of epithelium that lines the GIT
simple columnar
what are epithelial cells called?
enterocytes
what function does the epithelium in the lumen of the intestines?
absorption of the components of the digested food
what epithelial cells produce mucus?
goblet cells
what is the brush border in epithelial cells
composed of microvilli which increase surface area for absorption
what is the function of basal cells?
mitotically active- replaced damaged epithelial cells
where is stratified squamous epithelium found?
vagina or tongue
where is stratified columnar epithelium found?
parotid gland (salivary) or mammary gland
what are the extensions into the oesophagus?
papillae
where is transitional epithelium found?
urinary passages
what is the basement membrane composed of?
two layers:
- basal lamina
- reticular lamina
what is the basal lamina composed of?
glycoproteins: laminin and collagen, embedded in an amorphous matrix
what is the reticular lamina composed of?
reticular fibers embedded in ground substance
what acts as a selectively permeable barrier between the epithelium and connective tissue?
basal lamina
which is shorter: microvilli or stereocilia?
microvilli
what do microvilli contain?
actin filaments
does epithelium contain connective tissue?
no
what specializations support the function of epithelia?
desmosomes and intermediate junctions
what are desmosomes?
specializations of the lateral cell membranes that mediate cell adhesion
what are glands?
cells thats function is secretion
what are exocrine glands?
release the secretory product onto surface of the body
what are endocrine glands?
release secretory product, usually hormones, into the extracellular spaces between cells and then transfers to bloodstream
which type of glands maintains contact with the surface epithelium?
exocrine
an example of a unicellular gland
goblet cells
an example of a multicellular gland
secretory epithelial sheath- surface epithelium consisting entirely of secretory cells eg stomach
different forms of glands
tubular, acinar, alveolar
what type of gland is the pancreas
tubulo-acinar gland
what are the 3 secretory mechanisms?
apocrine, merocrine and holocrine
mechanism of apocrine secretion
part of the apical cytoplasm of the cells is lost together with the secretory product
mechanism of merocrine secretion
Vesicles open onto the surface of the cell, and the secretory product is discharged from the cell
mechanism of holocrine secretion
breakdown and discharge of the entire secretory cell ie sebaceous glands
