Epithelial Tissues VI Flashcards
The primary function of glands is
secretion of either specific bioactive molecules (e.g. hormones), complex fluids (e.g. mucous, sweat), or both
Exocrine glands
secrete materials onto epithelia-lined surfaces or the outside world.
Endocrine glands
secrete substances into the blood stream
Exocytosis:
glands secreting by this familiar, and most common, mechanism are sometimes called merocrine or apocrine glands
Total cell disintegration
leads to the entire cellular contents becoming part of the secretion; glands of this sort are less common, and are sometimes called holocrine glands (examples include the secretion of oily sebum onto hair and skin).
Exocrine glands secrete materials onto the _______ side of epithelial surfaces. They are generally _______ and are composed of 2 main components: _______ and _______
- apical
- multicellular
- secretory units
- ducts
However, some epithelial cells in the lining of internal passageways function as unicellular glands secreting materials directly onto those surfaces
- unicellular
- directly
secretory units
clumps of secretory epithelial cells which produce and secrete the bulk of the secretion
Secretory units can be organized into:
bowl/flask-shaped lobules called alveoli or acini
tubes called tubular
ducts
tubular structures that emanate from the secretory unit and function as passageways to conduct secretions to their destinations (epithelia can also modify the secretion content by secretory and ion transport properties)
Glands that possess a single duct are classified as ______, whereas those with multiple branched ducts are called _______.
- simple glands
- compound glands
mucous exocrine glands
viscous glycoprotein-rich fluid is produced
serous exocrine glands
water fluid containing salts and some specific proteins is produced
mixed exocrine glands
both kinds (glycoprotein-rich and salt) of secretions are produced
secretory epithelial cells of exocrine glands secrete materials ______ from their ______ surface ***with the exception of ______ secretion
- unidirectionally
- apical
- holocrine
endocrine glands produce mostly
specific hormones that act over relatively long distances to control tissue function
organization of endocrine glands
clumps or chords of cells that are embedded with and surrounded by CT containing extensive cap networks. each clump is surrounded by a basal lamina
because each endocrine clump is surrounded by a basal lamina but the blood caps are embedded in CT on the other side of the epithelial basal lamina,
hormone molecules must cross the basal surface and basal lamina of the epithelium (and finally the basal lam and endothelial layer of the cap) to reach the blood stream
because hormone molecules must cross so many layers to reach the blood stream,
most endocrine cells secrete them from the BL membrane
