Flashcards in lecture 10: pancreas + salivary glands Deck (30):
Describe two types of glands
Exocrine: develop from surface epithelium + retain contact with it
Endocrine: lose contact with surface epithelium
Name classes of exocrine glands
Simple = one straight, unbranched duct
compound = 2+ branches of ducts
What is the function of the three major places of glands in oral cavity?
production of saliva
what does saliva contain?
hypotonic + slightly alkaline
electrolytes: SODIUM, POTASSIUM, CHLORIDE, bicarb
proteins: amylase, lingual lipase, lysozyme, IgA, mucins, histidine-rich peptides, EGF, nerve growth factor
what do salivary duct cells do?
K, bicarbonate secretion
what kinds of proteins do salivary acini produce?
what kind of salivary glands are the sublingual, submandibular and parotid?
sublingual = seromucous, mucous
subamndibular = mostly serous, seromucous, mucous
parotid = serous
how does osmolality change from acinus to interlobular duct?
what are net effects on electrolyte transport in salivary ducts?
out of basolateral = Na and Cl
out to duct lumen = K and bicarbonate
what does ACh control?
salivary fluid and protein secretion
what are the functional parts of the pancreas?
exocrine = acini + ducts = digestion = majority
endocrine = islets of Langerhans = hormones = minor
what are the functions of the exocrine pancreas?
synthesis and secretion of digestive enzymes: proteases, lipases, amylase, nucleases
secretion of bicarbonate and water
what are the functions of the endocrine pancreas?
synthesis and secretion of hormones: insulin, glucagon, somatostatin, others (ghrelin, VIP)
what do cells in pancreatic acini do?
duct epithelial cells = secrete bicarbonate and water
acinar cells = make digestive enzymes = proteases, lipases, amylase
what kind of cells are mainly found in the islets of langerhans?
B cells, insulin
what's the composition of pancreatic juice?
electrolytes: Na, K, CHLORIDE, BICARBONATE
proteins: PROTEASES, amylase, lipases, nucleases, protease inhibitors
what are the net effects of electrolyte transport in duct epithelial cells?
out to basolateral surface: acid
out to apical side: bicarbonate
Describe what happens when pH drops in the duodenum after acid comes through pyloric sphincter.
1) the low pH and fatty acids stimulate S cells to secrete secretin
2) secretin stimulates duct cells in the pancreas to release bicarbonate
3) ACh and CCK potentiate bicarbonate response to secretin
4) bicarbonate travels out through sphincter of Oddi to counteract drop in pH
What kind of the proteins are most of the pancreatic secretory proteins?
why are proteases and lipases secreted as inactive from the pancreas?
they are secreted as inactive pro-forms (zymogens) to protect the pancreas from self-digestion
what do enterocytes produce that help with zymogen activation in intestinal lumen?
enterocytes in lumen of duodenum produce "enterokinase", a peptidase
what does enterokinase do?
enterokinase cleaves (thereby activating) trypsinogen into trypsin in the lumen of the duodenum
what does trypsin do?
trypsin activates other proteolytic enzymes (zymogens) coming in from the pancreas
what effect does CCK have on pancreatic enzyme secretion?
CCK stimulates pancreatic enzyme secretion
indirect stimulation via vagovagal reflexes
what neurotransmitters are involved in vagal stimulation of pancreatic acini for enzyme release?
what second messengers are associated with stimulation of pancreatic acinar cells at the basolateral surface?
VIP = cAMP
ACh, GRP, CCK = calcium
what does monitor peptide do?
secreted by acinar cells along with zymogens to inhibit prematurely activated trypsin
Describe the feedback regulation of CCK production in the fasting vs. fed states
monitor peptide, CCK-releasing factor will degrade trypsin - no CCK released
food proteins regulate degradation of CCK-releasing factors by competing with trypsin activity; CCK-RF remains intact and CCK gets released
What cells secrete bicarbonate/water in pancreas? What are the regulators?
ducts release bicarbonate, water
regulators = secretin, ACh, CCK