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Terms in this set (36)
Glands arise from ____ that penetrates into the underlying CT during development. Secretions are typically synthesized __ __ and stored in __ ___.
epithelium; in the cell; secretory granules
have ducts that retain a connection to the epithelial surface; secretions reach their target via ducts
lost connections to original (ductless) epithlium; secretions carried by blood or lymph, called hormones
How are exocrine glands categorized?
based on secretions; mode of secretion; structure
Exocrine glands produce what types of secretions?
mucous, serous fluid
secrete mucinogens- large glycoproteins that form viscous lubricant when hydrated. Mucin is this lubcricant and major component of mucous
histo: cube shaped cells; cytoplasm- very light due to water soluble graunles; nucleus- flattened at cell base; Mucous cell groupings in glands- most commonly mucous cells form the wall of tubules (grouped together as acini)
secrete watery serous fluid that is rich in enzymes
histo: pyramid shaped, and have a protein-secreting cell appearance ; nucleus- located in basal half of cell and is round; contains eosinophilic granules; serous cell groupings in glands- usually grouped into a bunched called acinus or alveolus. Cells secrete serous fluid into lumen at the center of acinus and lumen drains into a system of ducts.
contain both mucous and serous secretory units
Serous demilune- feature common to many mixed glands in which serous cells are wedged into mucous tubules or acini forming mixed gland
serous cells take on a half moon appearance
Name the 3 modes of secretion
Merocrine; Holocrine; Apocrine
release via exocytosis, most exocrine glands fall into this category (no release of cytoplasm and cell membrane)
the secretory cell itself becomes the secretory product (the whole cell or bulk contents of cytoplasm are released) (ex. sebaceous glands)
apical portion of cell cleaves from the cell resulting in release of a portion of the apical cytoplasm and cell membrane along with product. (i.e. mammary gland and sweat glands)
Exocrine glands are either ____ or ____
unicellular or multicellular
How are multicellular glands divided?
simple, compound, tubular, acinar, tubulo-acinar
simplest form of an exocrine gland, consisting of a single secretory cell situated among non-secretory cells
Goblet cell is by far the most common example of a unicellular gland.
read pg 7
have clusters of secretory cells organized in various structural patterns; do not function independently-- act as a secretory organ
acinus or alveolus (a spherical cluster of secretory cells)
Tubulo-acinar (comination of acinus and tubule within one secretory unit)
What else is used to subcategorize multicellular glands?
Duct branching pattern
glands with a single duct (duct is unbranched)
have an acinus emptying into a duct
simple tubular glands have a tubular secretory portion continous with the duct. Sweat glands are simple coiled tubular glands
glands with branched ducts
compound acinar glands have multiple acini, each one emptying into an intercalated duct
compound tubular glands have mulitple tubular secretory portions, each emptying into an intercalated duct
compound tubulo acinar glands- multi branched glands with tubular secretory portionst hat often end in acini, so both types of secretory units are present
subdivisions of a compound gland, each on epossessing many secretory units
glandular tissue within each lobule
CT that forms a supportive framework for parenchyma
The duct system of compound glands
ducts into which the secretory endpieces empty. Ducts have a diamter small than the acini and are lined by cuboidal cells
Striated intralobular ducts
several intercalated ducts merge to form:
cuboidal cell-lined ducts within a lobule, larger than the intercalated ducts
originate from the basal surface of the cuboidal cells. EM demonstarates that the striations come from membrane folds with many mitochondria in the folds
cuboidal cells actively reabsorb Na from the duct lumen and secrete enzymes and other components into it
Interlobular, or ___, ducts
intralobular ducts drain into these
larger ducts located in CT septa between lobules
epithelial lining is simple columnar
What are the major accessory exocrine glands associated with the GI?
salivary and exocrine
describe salivary glands
three pairs of large glands- with contributions from oral cavity glands- produce saliva
function of saliva:
lubrication: function of water and glycoproteins, primarily secreted by mucous cells
solvent- for substances that excite taste buds
carbohydrate digestion- initiated by enzyme amylase present in saliva
anti-bacterial function- result of the enzyme lysozyme, which lyses bacteria
immunological defense- resulting from Ig that bind a secretory compound synthesized by serous acinar cells and intercalated ducts -- resits enzymatic digestion protecting the antibody
composed of collageouns CT suurounds each of the major salivary glands
extensions of CT form interlobular septa
Name the three major paired salivary glands
Parotid glands- inferior and anterior to the ears
structure- largest salivary glands; compound acinar glands; serous only; well developed CT capsule with many lymphoid cells that produce Ig
submandibular (submaxillary glands)- located wither side of the floor of the mouth; structure: mixed compound tubulo-acinar, serious secretory units outnumber the mucous secretory units
sublingual glands: located on the floor of the mouth; the duct sometimes joins that of the submandibular gland
structure: mixed compound tubulo-acinar, a majority of secretory units are mucous and most serous cells are in serous demilunes
Pancreas lies posterior to the peritoneum along the posterior abdominal wall. has clusters of endocrine cells (islets of langerhans) interspersed among exocrine tissue.
The exocrine pancreas is __ __ and is exclusively __
compound acinar; serous
What are the characteristics exclusive to the pancreas?
islets of langerhans: endocrine portion
centroacinar cells: pale cells in the center of each acinus that represent the beginning of the intercalated duct (striated ducts are not present- short intercalated ducts enter into intralobular ducts. They do not possess basal striations)
Pancreas has a thin connective tissue capsule that projects into the pancreas, dividing it into lobules. Main duct has a common opening with the common bile duct into the duodenum
What are the major controls of the exocrine pancreas secretions?
CCK: hormone produced by duodenal enteroendocrine cells. INduces cells to release their enzymes
Secretin: hormone produced by duodenal enteroendocrine cells. However, this hormone promotes secretion of large quantities of bicarb-rich, enzyme poor fluid that is used to optimize pH
secretin + CCK= final secretory product
vagus nerve- nervous control is secondary to the hormonal control .
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