Digestive Glands Flashcards
(22 cards)
what does the parenchyma of digestive glands derive from?
epithelium of the gut tube (endoderm)
what are the 3 major salivary glands? what do they secrete?
parotid- all serous, submandibular- mostly serous, some mucous, sublingual- mostly mucous, some serous
what is the structure of salivary glands?
branched acinar
serous demilune
found in salivary glands with mixed sero-mucous
what are the classifications of ducts draining salivary glands?
intralobular- within lobules and interlobular- between lobules
what are the two types of intralobular ducts and what is their structure?
smaller- intercalated. simply squamous. closer to gland. intercalated ducts drain into striated ducts. striated ducts are larger and have cuboidal or columnar epithelium.
why are striated ducts striated?
their basal membranes have extensive folding and mitochondria accumulate there creating the pattern
what type of cell is responsible for the movement of gland secretion in parotid, submandibular and sublingual glands?
myoepthelium
describe the structure of an interlobular duct
pseudostratified columnar or, in large ducts, stratified columnar
how does the duct modify the secretion in salivary glands?
striated ducts reabsorb Na and Cl to create a hypo-osmotic solution. they also contribute IgA and lysozyme
describe 3 ways in which the exocrine pancrease differs from the salivary glands
no striated ducts. no mucous secretion (only serous). retrograde extension of the intercalated ducts into the lumen of the acinar gland.
what is the purpose of the retrograde extension of the intercalated ducts
they contribute large amounts of alkaline bicarbonate to the secretion. this will neutralize acidic gastric contents in the duodenum
what are the 2 general types of secretions of the pancreas? how is each regulated?
enzymes- proenzymes- amylase, lipase, trypsinogen, etc. controlled by cholecystokinin. water and ions (bicarbonate)- controlled by secretin
what are centroacinar cells?
the cells that have been extended backwards from the duct into the lumen of the pancreatic glands
describe what happens to blood after it travels through the portal triad
portal triads (branches off bile duct, portal vein, and hepatic artery) are located peripherally. branches will flow inward from the periphery, mix together, and pass through sinusoids on their way to a central vein. hepatocytes have their basal membrane adjacent to the sinusoids, thus can exchange materials
kupffer cells
resident liver macrophages found in the endothelium of sinusoids
ito cells
vitamin a storage and local immunity, found in the per-sinuoidal space of disse (between the sinusoid and basal membrane
describe the different sides of a hepatocyte
basal- faces sinusoid. apical- create walls of bile canaliculi. lateral- adjacent with other hepatocytes
how does bile get secreted from hepatocytes
exocytosed out the apical membrane into bile canaliculi, which travel out into terminal ductules (canals of Hering) and ultimately into the portal triad
describe the inner wall of the gallbladder
mucosa made of simple columnar epithelium, lamina propria, no muscularis mucosa. the wall is itself folded and the columnar epithelium have microvilli to increase surface area for concentrating bile
describe the outer layer of the gallbladder
facing the peritoneum- lined by a visceral membrane. facing the liver, lined by a tunica adventitia
how does the gallbladder concentrate bile?
it pumps Na and Cl out of the lumen, causing water to follow
