Physiology Of Gastric Secretion

Question 1

What does the orad region of the stomach consist of?

Answer 1

Fungus and Proximal Body (storage of the stomach)

Question 2

What does the caudad region of the stomach consist of?

Answer 2

Distal body and Antrum (where propulsion/grinding occurs)

Question 3

Mechanical activity occurs as two types in the stomach. What are they?

Answer 3

• Orad stomach (fungus and proximal body): tonic i.e. maintained
• Caudad stomach (distal body and antrum): physical i.e. intermittent

Question 4

What is propulsion and grinding in the stomach respectively?

Answer 4

• The movement of food via peristaltic contractions of the smooth muscle from the fundus towards the contracted pylorus
• Turning the chyme into smaller particles

Question 5

What is the capacity of the stomach and how many litres of gastric juices does it secret a day?

Answer 5

• 50>1000ml
• secrets approximately 2 litre/day of gastric juice from gastric glands in the gastric mucosa

Question 6

What brings about the relaxation of the fundus?

Answer 6

Autonomic system:
Vagal afferents -> acetyl choline release -> bind to M receptors on smooth muscle of fundus -> relaxation -> allows a greater area in the fundus to turn food into chyme

Question 7

What is the electrical and mechanical activity of the orad region of the stomach

Answer 7

During a swallow (which is simultaneous with the opening of the lower oesophageal sphincter), relaxation occurs via vagus afferents permitting storage of ingested material.
Tonic contractions - they are weak due to relatively thin musculature
These low amplitude tonic contraction last about 1 min and propel contents to Caudad region.

Question 8

What is the minimal amount of time for mixing of contents in the stomach and why?

Answer 8

1 hour to allow carbohydrate partial digestion by salivary amylase

Question 9

What is the electrical and mechanical activity of the Caudad region of the stomach

Question 10

Where do you find the gastric bubble in a image?

Answer 10

In the fundus

Question 11

Where is the majority of gastrin secreted from?

Answer 11

G cells in antrum of the stomach

Question 12

What does gastrin do?

Answer 12

• increase gastric motility
• stimulates parietal cell maturation
• increases pepsinogen secretion
• increases gastric H+ secretion

Question 13

What does somatostatin do?

Answer 13

• decreases gastric emptying
• decreases pepsinogen secretion
• decreases gastric H+ secretion
• decreases gallbladder contraction
• decreased pancreatic secretions

Question 14

What does VIP do?

Answer 14

• increases secretion of water from pancreas and intestines
• decreases gastric H+ secretion

Question 15

What does secretin do?

Answer 15

• increases pancreatic bicarbonate secretion
• decrease gastric H+ secretions

Question 16

What does CCK do?

Answer 16

• increases pancreatic secretions rich in digestive enzymes
• decreases gastric emptying
• increases gallbladder contraction

Question 17

Where is majority of CCK secreted from?

Answer 17

I cells in the upper small intestine

Question 18

Where is the majority of somatostatin released from?

Answer 18

D cells in the pancreas and stomach

Question 19

What does leptin do?

Answer 19

Decrease appetite

Question 20

What decreases gastric H+ secretion?

Answer 20

• secretin
• VIP
• somatostatin

Question 21

What increases gastric H+ secretion?

Answer 21

• gastrin