GI 4- Accessory GI Organs- Pancreas, Liver and Gall Bladder

Question 1

What do the acinar cells of the pancreas do?

Answer 1

synthesize and secrete hydrolases for digestion

Question 2

What do the duct cells of the pancreas do?

Answer 2

secrete bicarbonate and water

Question 3

How does the pancreas make the small intestine neutral pH?

Answer 3

Neutralizes gastric H+ by secreting HCO3-

Question 4

Why Doesn’t the Pancreas Digest Itself?

Answer 4

• Proteolytic enzymes synthesized, stored and secreted as inactive precursors.
• Activated in intestinal lumen

Question 5

What are the proteolytic enzymes of the pancreas?

Answer 5

enterokinase
trypsin

Question 6

What are the two stimuli for acini cells in the pancreas?

Answer 6

CCK
ACh/GRP (vasovagal reflux

Question 7

What does CCK stimulate?

Answer 7

• gallbladder contraction
• sphincter of oddi relaxation
• acinar secretion
• reduced stomach emptying
• reduced HCl secretion

Question 8

What two substances cause the secreting of CCK through the I cell?

Answer 8

CCK-RP
monitor peptide

Question 9

What is the main funtion of trypsin?

Answer 9

• breakdown proteins
• if most proteins are broken down then it activates CCK-RP and monitor peptide (causes increased CCK)

Question 10

What causes an increase in CCK-RP which in turn increases CCK?

Answer 10

fatty acids and peptides in the intestinal lumen

Question 11

What are the two stimuli for the ductal cells in the pancreas?

Answer 11

secretin
ACh

Question 12

What do secretin and ACh stimulate the ductal cells to do?

Answer 12

release bicarbonate and neutralize the pH of the small intestine

Question 13

What is the function of secretin?

Answer 13

➢ cAMP
➢ Phosphorylation of CFTR
➢ increased Cl- conductance
➢ increased HCO3- secretion

Question 14

Secretin released when pH < ___

Answer 14

4.5

Question 15

What is secreted more in the presence of HCl: secretin or CCK?

Answer 15

secretin (ductal cells)

Question 16

What is secreted more in the presence of soap/fats: secretin or CCK?

Answer 16

about equal

Question 17

What is secreted more in the presence of peptone: secretin or CCK?

Answer 17

CCK (acinar cells)

Question 18

What mediates the cephalic and gastric phases of pancreatic secretion?

Answer 18

Both phases mediated by vagovagal reflex - low volume, high enzyme secretion (Ach/GRP)

Question 19

What happens during the intestinal phase of pancreatic secretion?

Answer 19

• acid causes the release of secretin which causes increased HCO3- and H2O
• fats/proteins indirectly cause in increase in CCK through CCK-RP and monitor peptides which then releases enzymes

Question 20

If the pancreatic secretion rate is low what happens to bicarb and Cl?

Answer 20

− bicarbonate concentration is low
− chloride concentration is high

Question 21

If the pancreatic secretion rate is high what happens to bicarb and Cl?

Answer 21

− bicarbonate concentration is high
− chloride concentration is low

Question 22

Pancreatic juice is hypertonic, hypotonic, or isotonic?

Answer 22

isotonic

Question 23

What does cystic fibrosis do to pancreatic function?

Answer 23

➢ Abnormal sweat composition.
➢ Decreased pulmonary and pancreatic secretion.
➢ Mendelian autosomal recessive
➢ Defective CFTR:
– Sweat Cl- reabsorption
– Pancreatic duct cell function
– Pulmonary mucus clearance

Question 24

What is pancreatitis?

Answer 24

– Acute and chronic
– Trypsin activation causes pain, inflammation
– Chronic disease destroys acini
– Consequences reflect decreased digestive enzyme production

Question 25

What can happen without pancreatic enzymes?

Answer 25

− 60% fat not absorbed (steatorrhea) − 30-40% protein and carbs not absorbed

Question 26

What is the function of the liver?

Answer 26

➢Cleansing and storage of blood ➢Metabolism of nutrients ➢Synthesis of proteins ➢Metabolism of hormones ➢Storage of energy, vitamins, iron ➢Excretion of lipid-soluble waste products ➢Marked capacity for cellular regeneration ➢Secretion of bile

Question 27

Cirrhosis increases resistance and produces ____________

Answer 27

portal hypertension

Question 28

Increased vascular resistance in the liver can cause _______

Answer 28

ascites

Question 29

What is the role of bile salts (acids)?

Answer 29

- Bile salts (acids) and lecithin required for emulsification and absorption (micelles) of dietary fat. - Excretion of lipophilic metabolites (bilirubin), excess cholesterol, other waste products, drugs, and toxins

Question 30

What secretes bile salts,cholesterol, lecithin, bilirubin, many other lipophilic substances?

Answer 30

hepatocytes

Question 31

Duct epithelial cells modify primary secretion from pancreas and add...

Answer 31

HCO3-

Question 32

Where can bile be transported after being secreted from the liver?

Answer 32

1. Small intestine for fat digestion 2. Gall Bladder for storage

Question 33

Electrolytes and water reabsorbed or secreted from bile while in Gall Bladder?

Answer 33

reabsorbed

Question 34

If someone has a cholecystectomy can they still digest fat?

Answer 34

YES ➢ No problems with fat digestion ➢ Bile flow directly into duodenum

Question 35

What hormone stimulates liver ductal secretion via the blood stream?

Answer 35

secretin

Question 36

What causes weak contraction of the gallbladder?

Answer 36

vagal stimulation

Question 37

What causes gallbladder contraction and relaxation of the sphincter of oddi?

Answer 37

CCK

Question 38

What is the enterohepatic circulation of bile salts?

Answer 38

➢Substance secreted into bile by hepatocytes. ➢ Delivered to lumen of ileum, then reabsorbed. ➢ Transported to hepatocytes via sinusoids ➢ 94% of bile salts recirculated ➢ Bile salts circulate 17x before lost in feces.

Question 39

What transporter allows for active absorption of bile salts?

Answer 39

Apical sodium-dependent bile salt transporter (ASBT)

Question 40

What are bile acid reabsorption inhibitors (BARI)?

Answer 40

➢ Drugs that inhibit Bile Recycling ➢ Used to lower LDL levels in blood

Question 41

What are the different types of bile acid reabsorption inhibitors (BARI)?

Answer 41

- bile acid sequestrants (bined to bile salts in lumen and block transport) - ASBT inhibitors (new drug that reduces cholesterol levels in ECF)

Question 42

What is low Apical sodium-dependent bile salt transporter (ASBT) activity associated with?

Answer 42

➢Crohn’s disease ➢Congenital 1° bile acid malabsorption ➢Idiopathic chronic diarrhea ➢Irritable Bowel Syndrome