Pancreas and gallbladder

Question 1

What are the 2 types of receptors in the duodenum sensitive to?

Answer 1

1. Acid.

2. Fatty acids and proteins.

Question 2

When stimulated by acid, what does the duodenum release?

Answer 2

Secretin

Question 3

When stimulated by fatty acids/proteins, what does the duodenum release?

Answer 3

CCK

Question 4

Where does the duodenum release secretin and CCK into?

Answer 4

Pancreaticoduodenal artery

Question 5

What cells does secretin act on in the pancreas, and what does it stimulate?

Answer 5

Acinar cells secrete bicarbonate.

Question 6

What cells does CCK act on in the pancreas, and what does it stimulate?

Answer 6

Acinar cells secrete digestive enzymes.

Question 7

When do pancreatic secretions begin?

Answer 7

At the cephalic phase of eating, through vagal stimulation.

Question 8

Through what does the pancreas secrete? (describe anatomy).

Answer 8

Pancreatic duct, which joins the common bile duct just before it empties into the duodenum through the ampulla of Vater, which is surrounded by the sphincter of Oddi.

Question 9

What enzymes does the pancreas secrete that digest peptides?

Answer 9

Trypsin
Chymotrypsin
Carboxypolypeptidase

Question 10

What enzymes does the pancreas secrete that digest carbohydrates?

Answer 10

pancreatic amylase

Question 11

What enzymes does the pancreas produce that digest fats?

Answer 11

Pancreatic lipase
Cholesterolesterase
Phospholipase

Question 12

What prevents the peptide digestion enzymes from digesting the pancreas before secretion?

Answer 12

They are in a pro-enzyme form:
Trypsinogen
Chymtrypsinogen
Procarboxypolypeptidase.

These are converted into active enzymes once in the duodenum.

ADDITIONALLY

The enzyme ‘Trypsin inhibitor’ prevents these pro-enzymes from becoming active in the pancreas.

Question 13

What activates trypsongen (into trypsin)?

Answer 13

enterokinase, secreted by the intestinal mucousa.

Trypsin itself also activates trypsinogen into trypsin.

Question 14

What activates chymotrypsinongen and procarboxypolypeptidase into chymotrypsin and carboxypolypeptidase?

Answer 14

Trypsin

Question 15

What may become a problem in acute pancreatitis wrt trypsinogen?

Answer 15

if there is a pooling of pro-enzymes in the pancreas, they may overcome the effect of trypsin inhibitor, and then further self activate (via trypsin). The pancreas will start to digest itself.

Question 16

What do the Islets of Langerhans produce?

Answer 16

insulin
Glucagon
Somatostatin
Polypeptide

Question 17

What are the two main causes of acute pancreatitis?

Answer 17

1. Gallstone
2. Alcohol

There are many other idiotpathic causes, with some pathologies still completely elusive.

Question 18

How does cystic fibrosis affect the pancreas?

Answer 18

Failure to properly hydrate the pancreas, leading to increased viscosity of secretions, leading to obstruction.

CF is the leading cause of pancreatitis on children.

Question 19

Acute pancreatitis symptoms

Answer 19

PAIN - EPIGASTRIC, latterly through to back once inflammations has spread throughout peritoneal cavity.
N&V

Question 20

signs of acute pancreatitis

Answer 20

tenderness on exam
guarding
reduced bowel sounds
tachycardia
hypotension

If gall bladder problem too:
jaundice.

Question 21

Investigations for acute pancreatitis

Answer 21

Serum amylase
serum lipase
ABG for acid/base status
CXR - exclude perforation
USS
CT after 72 hours

Question 22

What tumour marker can be used to help diagnose and monitor pancreatic cancer?

Answer 22

CA19-9

Question 23

What is the purpose of bile secretion?

Answer 23

Aids fatty acid digestion.

Excretion of bilirubin - (end product of haemaglobin destruction, and excess cholesterol).

Question 24

How is bile concentrated?

Answer 24

active transport of Na through the gall bladder epithelium, followed by secondary absorption of water and chloride ions.

Bile can be concentrated up to 20x this way.

Question 25

What causes the gall bladder to secrete?

Answer 25

Fatty foods in duodenum,
release of CCK,
rhythmic contraction of gall bladder wall.

Question 26

How do bile acids enable digestion of fat?

Answer 26

They are amphipathic, therefore emulsify fats and break them down into micelles. This enables the pancreatic lipase to act on them. The micelles progressively get smaller, and contain more broken down products.

Question 27

What do the pancreatic lipolytic enzymes break the contents of bile conjugated micelles down into?

Answer 27

Fatty acids, monoglycerides, cholesterol.

Question 28

What are primary bile salts conjugated to?

Answer 28

Taurine or Glycine

Question 29

What is the destiny of primary bile salts?

Answer 29

Primary bile salts can be reabsorbed. The ones which are not pass to the ileum and colon where bacteria deconjugate them from taurine and glycine to become secondary bile salts.

Question 30

What happens to secondary bile salts?

Answer 30

some are reabsorbed, reconjugated by the liver and recirculated.
some are excreted.

Question 31

How are bile salts reabsorbed?

Answer 31

Active transport in the ileum into the enterohepatic circulation.

Question 32

How are reabsorbed bile salts transported in the enterohepatic circulation?

Answer 32

conjugated to albumen.

Question 33

What is enterohepatic circulation of bile salts?

Answer 33

95% of bile salts are reabsorbed by diffusion on the proximal intestine, and active transport more distally. They are transported, conjugated to albumen in the portal blood and are reconjugated to taurine or glycerol in the liver before passing to the gall bladder again.

Question 34

Describe the fate of a fragile RBC up to the point where it enters the liver

Answer 34

Cell membrane ruptures.
Macrophages phagocytose the Haeme.
Haeme is made into biliverdin, which is immediately reduced into unconjugated bilirubin.
Bilirubin is then released from the macrophage into plasma where it combines with albumen in the systemic circulation - where it will pass into the liver.

Question 35

Describe what happens to bilirubin in the liver.

Answer 35

It enters the liver as unconjugated, is absorbed by hepatocytes, and is conjugated before being secreted into the bile canaliculi and being transported to the gall bladder.

Question 36

Describe what happens to bilirubin after it has reached the gall bladder.

Answer 36

It is secreted into the duodenum as part of bile, and bacterial action in the intestine converts it into urobilinogen.

Question 37

Describe the 3 different paths that urobilinogen may take

Answer 37

Some is absorbed into the portal system ends up at the kidneys where it is excreted.
Some is absorbed into the portal system and ends up in the liver where it is re-secreted through the gall bladder.
Some remains in the intestine where it is oxidised to form stercobilin before being excreted.

Question 38

What is Haemolytic jaundice?

Answer 38

bilirubin excretion is normal, but the haemolysis of RBCs is too rapid and the excretion process cannot keep up.

Question 39

What is obstructive jaundice?

Answer 39

problem with the excretion of bilirubin.

This may be due to a physical obstruction, or hepatic impairment.

Question 40

What is the difference in levels of conjugated and unconjugated levels of bilirubin in obstructive and haemolytic jaundice and why?

Answer 40

In haemolytic jaundice, there is an increase in the levels of unconjugated bilirubin; the liver and gall bladder cannot deal with the excess quickly enough.

In obstructive jaundice, there are normal levels of unconjugated bilirubin entering the liver, so it gets conjugated normally. However, it cannot be excreted, so it leaks into plasma, causing an increase in plasm levels of conjugated bilirubin.