Lecture 40 11/27/23

Question 1

Which functions of hormones/secretions in the duodenum and jejunum are associated with providing time for present food to process?

Answer 1

-decreased appetite
-inhibition of gastric acid secretion
-slowing of gastric emptying

Question 2

Which functions of hormones/secretions in the duodenum and jejunum are associated with optimizing digestion?

Answer 2

-releasing bicarbonate to neutralize acidic chyme
-stimulating digestive enzyme secretion
-stimulating bile acid secretion

Question 3

What are the stimuli for secretin production?

Answer 3

-low duodenal pH
-intraduodenal nutrients

Question 4

What are the actions of secretin?

Answer 4

-inhibit acid secretion
-slow gastric emptying
-stimulate HCO3-rich pancreatic fluid secretion

Question 5

Which enzyme is involved in sodium-bicarbonate buffering of hydrochloric acid?

Answer 5

carbonic anhydrase

Question 6

What are the stimuli for cholecystokinin (CCK)?

Answer 6

-intraduodenal nutrients
-H+ ions

Question 7

What are the actions of CCK?

Answer 7

-inhibit gastric emptying
-increase secretin secretion
-increase pancreatic enzyme secretion
-stimulate pancreatic growth
-cause gall bladder to contract
-relax sphincter of Oddi in the gall bladder

Question 8

What is the stimulus of gastric inhibitory peptide?

Answer 8

intraduodenal nutrients

Question 9

What are the actions of gastric inhibitory peptide?

Answer 9

-inhibition of gastric acid secretion
-stimulation of pancreatic insulin release when blood sugar is high (incretin)

Question 10

What is an incretin?

Answer 10

a substance that increases insulin release

Question 11

Which type of pancreas makes up the majority of the pancreas?

Answer 11

exocrine

Question 12

How is the exocrine pancreas arranged?

Answer 12

into acini and ducts

Question 13

What are the characteristics of pancreatic enzyme secretion?

Answer 13

-secreted by acinar cells
-stimulated by CCK and acetylcholine

Question 14

What are the characteristics of bicarbonate-rich fluid secretion?

Answer 14

-secreted by ductal cells
-stimulated by secretin

Question 15

What are zymogens?

Answer 15

the precursor molecules of protein-digesting enzymes

Question 16

Why are protein-digesting enzymes produced as zymogens first, instead of in their active form?

Answer 16

active form could break down pancreatic tissue

Question 17

Where are zymogens activated into protein-digesting enzymes?

Answer 17

duodenal lumen

Question 18

What are the characteristics of trypsinogen?

Answer 18

-activated into trypsin
-activated by enterokinase
-trypsin activates the other protein-digesting enzymes

Question 19

Which zymogens are activated by trypsin?

Answer 19

-chymotrypsinogen -> chymotrypsin
-procarboxypolypeptidase -> carboxypolypeptidase

Question 20

What are the characteristics of trypsin inhibitor?

Answer 20

-secreted by glandular cells of the pancreas
-prevent premature activation of trypsin

Question 21

What is amylase?

Answer 21

the carbohydrate-digesting enzyme

Question 22

Which form of amylase is the main enzyme for starch digestion?

Answer 22

pancreatic amylase

Question 23

What are the three fat-digesting enzymes?

Answer 23

-pancreatic lipase
-cholesterol esterase
-phospholipase

Question 24

What are the characteristics of sodium-bicarbonate?

Answer 24

-produced by pancreatic ductal cells
-secretion stimulated by secretin

Question 25

What are the functions of sodium-bicarbonate?

Answer 25

-buffer gastric acid coming from the stomach -provide volume to carry digestive enzymes from pancreatic acini

Question 26

Which hormone/secretion is the main trigger for enzyme release?

Answer 26

CCK

Question 27

What are the regulatory characteristics of acetylcholine?

Answer 27

-released from parasympathetic vagus nerve -stimulates acinar cells to release enzymes

Question 28

What are the regulatory characteristics of CCK?

Answer 28

-secreted from duodenum/jejunum -stimulated by intraduodenal nutrients -stimulates acinar cells to release enzymes

Question 29

What are the regulatory characteristics of secretin?

Answer 29

-secreted from duodenum/jejunum -stimulated by low duodenal pH -stimulate pancreatic duct cells to release water and sodium-bicarbonate

Question 30

Which phase of secretion sees the most pancreatic secretion occuring?

Answer 30

intestinal phase

Question 31

What are the characteristics of bile?

Answer 31

-secreted by hepatocytes into canaliculi -flows progressively into larger ducts until reaching hepatic and common bile ducts -can enter duodenum or be stored in gall bladder

Question 32

What does bile consist of?

Answer 32

-bile salts -pigments -cholesterol -phospholipids -electrolytes -bicarbonate

Question 33

What are the functions of bile?

Answer 33

-fat digestion and absorption -removal of waste products

Question 34

Which secretion triggers the release of bile?

Answer 34

CCK

Question 35

What are the characteristics of bile acids?

Answer 35

-steroid acids formed from cholesterol -act as detergents and make lipids soluble in water

Question 36

What are the characteristics of bile salts?

Answer 36

-conjugated bile acids -conjugated to amino acids (glycine or taurine)

Question 37

What is the main characteristic of primary bile acids?

Answer 37

produced by the liver

Question 38

What are examples of primary bile acids?

Answer 38

-cholic acid -chenodeoxycholic acid

Question 39

What are the characteristics of secondary bile acids?

Answer 39

-have been deconjugated and dehydroxylated -formed by action of bacteria on bile salts in the intestines

Question 40

What are examples of secondary bile acids?

Answer 40

-deoxycholic acid -lithocholic acid

Question 41

What are the characteristics of bile acid recovery?

Answer 41

-majority of bile acids are recirculated -reabsorbed in ileum -enter portal system and go to liver -liver recovers and conjugates bile acids

Question 42

What are the characteristics of emulsification?

Answer 42

-breaks large fat particles into small particles -provides larger surface area for lipase enzymes to attack

Question 43

What are the steps of making lipids water soluble?

Answer 43

-bile salts combine with dietary fats to form micelles -micelle formation allows dietary fats to cross aqueous layer to enter enterocytes

Question 44

What is the stimulus for peptide YY?

Answer 44

detection of material within distal intestines and colon

Question 45

What are the actions of peptide YY?

Answer 45

-signals satiety -inhibits gastric emptying