GI

Question 0

What do chief cells secrete?

Answer 0

Pepsin (proteolytic enzymes)

Non specifically break down proteins

Question 1

What do parietal cells secrete?

Answer 1

HCl

Keeps luminal pH of stomach lower than 2

Question 2

What do neck cells secrete?

Answer 2

Mucus
Basic due to amine groups on the proteins

HCO3-
Secreted into the mucus, provides a buffer for H+

Question 3

What do G cells secrete?

Answer 3

Gastrin

Question 4

What does gastrin do?

Answer 4

Binds to surface receptors on parietal cells, stimulating acid and intrinsic factor

Question 5

Which gastric gland cells secrete HCl?

Answer 5

Parietal cells

Question 6

Which gastric gland cells secrete pepsin?

Answer 6

Chief cells

Question 7

Which gastric gland cells secrete gastrin?

Answer 7

G cells

Question 8

Which gastric pit cells secrete mucus and HCO3-?

Answer 8

Neck cells

Question 9

Which cells secrete the bile acid dependent component of bile?

Answer 9

Hepatocytes lining the canaliculi

Question 10

What are the bile acids?

Answer 10

Cholic acid/ chenodeoxycholic acid

Question 11

How do bile acids travel?

Answer 11

Conjugated to amino acids in micelles

Bile salts, cholesterol, phospholipids

Question 12

Which cells secrete the bile acid independent component of bile?

Answer 12

Cells lining the intra-hepatic bile ducts

Question 13

What is the enterohepatic circulation?

Answer 13

Bile acids are released from the micelles when fatty acids are absorbed in the small intestine. The bile acids continue along the small intestine to the terminal ileum, where they are absorbed by the epithelia, then flow in the hepatic portal circulation to the hepatic sinusoids. Hepatocytes take up the acids and re secrete them into canaliculi

Question 14

Describe the biliary tree

Answer 14

Bile canaliculi ➡️ canals of Hering ➡️ intrahepatic bile ductile ➡️ interlobular bile duct ➡️ left and right hepatic ducts ➡️ common hepatic duct ➡️ common bile duct as it joins the cystic duct ➡️ ampulla of Vater as the pancreatic duct joins ➡️ duodenum

Question 15

List the secretions of the exocrine pancreas

Answer 15

Proteases- trypsin(ogen), chymotrypsin, elastase, carboxypeptidase
Amylases
Lipases

Question 16

How are pancreatic secretions stimulated?

Answer 16

Acinar (enzymes) - CCK and gastrin in response to hypertonicity and fats

Ductal (HCO3)- secretin in response to low pH

Question 17

How are biliary secretions stimulated?

Answer 17

CCK released from I cells of the duodenum due to hypertonicity, peptides and fat stimulate gall bladder contractions

Question 18

What would you suspect if you found eosinophils?

Answer 18

Parasitic infection eg worms, asthma, hay fever

Question 19

Which bonds does pepsin prefer breaking?

Answer 19

Peptide bonds near aromatic AA side chains

Question 20

Which bonds does trypsin prefer breaking?

Answer 20

Peptide bonds near basic AA side chains

Question 21

Which bonds does chymotrypsin prefer breaking?

Answer 21

Bonds near aromatic AA side chains

Question 22

Which bonds does carboxypeptidase prefer breaking?

Answer 22

C terminal AAs with basic side chains

Question 23

What immunological cells are found in Ulercative Collitis?

Answer 23

Th2 Helper cells which produce TGF- and IL-5

Question 24

What immune cells are found in Crohn’s?

Answer 24

Th1 helper cells which produce IFN-gamma and IL-2

Activation of Th1 cells produce the down regulatory cytokines IL-10 and TGF-