pancreas and salivary gland physiology

Question 1

constituents of saliva and functions

Answer 1

water: dissolves nutrients and for taste. Amylase: digestion of starches. Bicarbonate: neutralizes gastric acid. Mucins: lubrication. Lysozyme/lactoferrin/IgA: innate and acquired immune protection. Epidermal and nerve growth factors: mucosal growth and protection

Question 2

components of salivary gland

Answer 2

acinar cells make saliva which is passed through intercalated duct to the striated duct cells which modify ionic contents

Question 3

ANS regulation of salivary secretion

Answer 3

Parasympathetic – increased acinar cell secretion and vasodilation of blood vessels surrounding the acini (results in protein rich & fluid/ion rich solution). Sympathetic – increased acinar cell secretion (results in high protein/low fluid solution)

Question 4

How is saliva formed

Answer 4

passive filtration- Increased blood flow around the acinus increases the fluid content of saliva by moving ions and water cellularly and paracellularly into the acinar lumen. TJs are leaky in the acinus. Then duct cells modify saliva

Question 5

Saliva at high vs low flow rates

Answer 5

At high flow rates, saliva is slightly hypotonic and rich in bicarbonate, while at low flow rates it becomes quite hypotonic. At low flow rates, there is time for Na and Cl transport out of the lumen of striated duct plus bicarb and K are secreted into lumen. Ductal cells are impermeable to water

Question 6

Compare saliva levels of Na, bicarb, Cl and K in saliva relative to plasma

Answer 6

Na less than plasma. Bicarb greater than plasma. Cl less than plasma. K greater than plasma.

Question 7

What enzyme plays a role in bicarb production in bicarb regulation in ducts

Answer 7

carbonic anhydrase

Question 8

4. List the major ionic and peptide/protein components secreted by the pancreas.

Answer 8

trypsinogen, chymotrypsinogen, RNAse/amylase/lipase, etc. Water, bicarb

Question 9

Why are pancreatic enzymes produced as zymogens?

Answer 9

to prevent digestion of pancreas (autodigestion) leading to acute pancreatitis

Question 10

What stimulates pancreas acinar cell secretion

Answer 10

Chyme arriving at small intstine stimulates release of cholecystokinin which acts through second messengers IP3 and Ca to stimulate acinar cell secretions. Ach from vagus and ENS nerves also stimulates acinar secretion, as well as gastrin and secretin

Question 11

Which part of the pancreas produces enzymes vs aqueous components

Answer 11

enzymes: acinus. Aqueous: duct cells

Question 12

What stimulates secretion of bicarb in duct cells

Answer 12

acid in small intestine causes secretion of secretin from duodenal endocrine cells. Secretin stimulates bicarb release. Secretin and CCK also inhibit gastric acid/fluid production and delay gastric emptying until intestine is ready for more

Question 13

How does secretin work

Answer 13

increases cAMP levels in duct cells leading to bicarb secretion

Question 14

List the effects of CCK

Answer 14

contraction of gallbladder, acinar secretion in pancreas, reduced emptying of stomach, relaxation of sphincter of Oddi.

Question 15

What activates trypsin

Answer 15

enterokinase produced by small intestinal mucosa cleaves trypsinogen forming trypsin. Activated trypsin then autoactivates more trypsinogen alo

Question 16

Ion channels involved in pancreatic ductal cell secretion

Answer 16

Cl/bicarb exchanger in membrane of duct near lumen pushes bicarb into the lumen and Cl into the cell. There is also a CFTR Cl channel in the apical membrane which allows passive movement of Cl back into duct lumen. Carbonic anhydrase inside the duct cells plays role in bicarb generation from CO2 and water

Question 17

Pancreatic juice composition at low vs high flow secretion rates

Answer 17

low flow: low bicarb and high Cl. High flow: fluid moves through duct too fast to allow for significant exchange, so HCO3- is high, Cl- is relatively low

Question 18

Where is NaCl secreted in pancrease

Answer 18

acinar cells

Question 19

Phases of pancreatic secretion

Answer 19

cephalic- sight/thought/taste of food leads to vagal release of Ach (25-50%), gastric- distension of stomach (10%), intestinal phase- chyme in intestine leads to CCK release (50-100%)

Question 20

compare bicarb of saliva and pancreatic juice

Answer 20

salive: KHCO3. Pancreas: NaHCO3

Question 21

Benign neoplasms of salivary glands

Answer 21

mixed tumor (pleomorphic adenoma), monomorphic adenoma, ductal papilloma

Question 22

Pleomorhpic adenoma histology

Answer 22

Islands of cuboidal cells arranged in ductlike structures. Loose chondromyxoid stroma, connective tissue, cartilage (arrows) and even osseous tissue are observed.

Question 23

Warthins tumor

Answer 23

benign papillary cystadenoma lymphomatosum- commo in parotid gland.

Question 24

Warthins tumor diagnosis

Answer 24

lymphoid and ococytic epithelial elements

Question 25

Monomorphic adenoma

Answer 25

no mesenchymal stromal component, predominantly epithelial.

Question 26

mucoepidermoid carcinoma

Answer 26

mucin-producing cells and epithelial cells

Question 27

Adenoid cystic carcinoma

Answer 27

Swiss cheese pattern

Question 28

pancreatitis symptoms

Answer 28

upper abdominal pain, nausea/vomiting, weight loss and steatorrhea (oily, smelly stool)

Question 29

pancreatitis common causes

Answer 29

alcoholism, gallstone obstruction