GI Secretion, Digestion & Absorption

Question 1

What are the main gastric secretions and their daily volume?

Answer 1

Acids, enzymes, hormones, and intrinsic factors; ~2L per day.

Question 2

What are the key functions of gastric acid?

Answer 2

Activates pepsin, denatures proteins, kills bacteria, inactivates salivary amylase

Question 3

What is the role of pepsin in digestion?

Answer 3

It is an enzyme that breaks down proteins into smaller peptides.

Question 4

What is the function of somatostatin in the stomach?

Answer 4

It inhibits gastric acid secretion

Question 5

Why is gastric acid important for protein digestion?

Answer 5

It denatures proteins, making them more accessible for enzymatic digestion.

Question 6

How do NSAIDs and alcohol affect the gastric mucosa?

Answer 6

They destroy mucosal barriers, leading to gastric irritation and ulcers

Question 7

What is the function of the proton pump in gastric acid secretion?

Answer 7

The H⁺/K⁺ ATPase pump secretes hydrogen ions, making the stomach acidic.

Question 8

How does omeprazole work?

Answer 8

It irreversibly inhibits the H⁺/K⁺ ATPase proton pump, reducing gastric acid secretion

Question 9

What are histamine H2 receptor antagonists?

Answer 9

Drugs that block histamine-stimulated gastric acid secretion, e.g., cimetidine and ranitidine.

Question 10

Why was ranitidine discontinued in the UK?

Answer 10

Due to adverse drug reactions (ADRs)

Question 11

What is Helicobacter pylori and its effect on the stomach?

Answer 11

A bacterium that causes gastric mucosal inflammation, leading to ulcers.

Question 12

How is Helicobacter pylori treated?

Answer 12

With antibiotics to eliminate infection

Question 13

What is the role of intrinsic factor in digestion?

Answer 13

It binds to vitamin B12, facilitating its absorption in the small intestine.

Question 14

Why is vitamin B12 important?

Answer 14

It plays a crucial role in DNA synthesis and red blood cell (RBC) production.

Question 15

What are intestinal secretions composed of?

Answer 15

Mucus, digestive enzymes, and hormones

Question 16

What is the function of mucus in the duodenum?

Answer 16

Protects the duodenum from gastric acids and digestive juices.

Question 17

Which enzymes digest carbohydrates in the intestine?

Answer 17

Sucrase, lactase, maltase, and amylase.

Question 18

How are digested carbohydrates absorbed?

Answer 18

Through glucose transporters (SGLT, GLUTs)

Question 19

What is the role of cholecystokinin (CCK)?

Answer 19

Stimulates gallbladder contraction, pancreatic enzyme secretion, and inhibits gastric emptying.

Question 20

What does secretin do in digestion?

Answer 20

Stimulates bicarbonate secretion and inhibits gastric emptying.

Question 21

What is the function of gastric inhibitory peptide (GIP)?

Answer 21

e

Question 22

How does glucagon-like peptide-1 (GLP-1) affect digestion?

Answer 22

It inhibits gastric emptying and promotes satiety.

Question 23

What is bile and where is it produced?

Answer 23

A non-enzymatic digestive fluid produced by hepatocytes in the liver.

Question 24

What are the components of bile?

Answer 24

Bile acids, bilirubin, cholesterol, and bile salts

Question 25

How do bile salts aid digestion?

Answer 25

They emulsify fats, making them easier to digest and absorb

Question 26

What enzyme digests fats?

Answer 26

Pancreatic lipase

Question 27

How are fats absorbed in the intestine?

Answer 27

Monoglycerides (MGLs) break down into free fatty acids (FFA) and cholesterol, which diffuse into enterocytes

Question 28

What happens to absorbed fats and cholesterol?

Answer 28

They form chylomicrons and are removed through the lymphatic system

Question 29

What are the two types of pancreatic secretions?

Answer 29

Enzymatic (proenzymes from acinar cells) and bicarbonate (from duct cells).

Question 30

What is the role of bicarbonate in pancreatic secretions?

Answer 30

Neutralizes acidic chyme from the stomach and activates digestive enzymes.

Question 31

Which pancreatic enzyme digests fats?

Answer 31

Pancreatic lipase.

Question 32

Which pancreatic enzymes digest proteins?

Answer 32

Trypsin, chymotrypsin, and other proteases.

Question 33

Which pancreatic enzymes digest nucleic acids?

Answer 33

Nucleases.

Question 34

What is the function of the acinar cells in the pancreas?

Answer 34

They secrete inactive proenzymes (chymotrypsinogen, procarboxypeptidase, procolipase, etc.).

Question 35

What is the function of the duct cells in the pancreas?

Answer 35

They secrete bicarbonate to neutralize stomach acid.

Question 36

How does pancreatic lipase work?

Answer 36

It breaks down triglycerides into monoglycerides and free fatty acids.

Question 37

What is the primary function of the liver in digestion?

Answer 37

Produces bile, which helps in fat digestion

Question 38

What is the role of chylomicrons in fat absorption?

Answer 38

They transport absorbed fats and cholesterol through the lymphatic system.

Question 39

Which organ produces digestive enzymes for all macronutrients?

Answer 39

The pancreas

Question 40

Which organ is responsible for the majority of nutrient absorption?

Answer 40

The small intestine.

Question 41

How is the digestive function summarized?

Answer 41

The stomach digests proteins, the pancreas secretes enzymes, the liver produces bile, and the intestine absorbs nutrients.