Gastric Secretion

Question 1

What are the 3 main areas of the stomach?

Answer 1

Fundus
Body
Antrum

Question 2

What 2 areas of the stomach are used for storage?

Answer 2

Fundus

Body

Question 3

What 4 substances does the body of the stomach secrete?

Answer 3

Mucus
HCl
Pepsinogen
Intrinsic factor

Question 4

What are the 2 functions of the antrum?

Answer 4

Mixing/grinding

Secretion of gastrin (hormone)

Question 5

What is the dipped area before a gastric gland called?

Answer 5

Gastric pit

Question 6

What are the 3 types of cell (from gastric pit descending) found in the gastric gland?

Answer 6

Mucous neck cells
Chief cells
Parietal cells

Question 7

What substances do the following cells secrete:

a) Mucous neck cells
(b) Chief cells
(c) HCl (2

Answer 7

(a) mucus
(b) pepsinogens
(c) HCl & intrinsic factor

Question 8

What cells secrete gastrin?

Answer 8

G cells

Question 9

What are the 3 main mechanisms of control for gastric acid secretion and how are they regulated?

Answer 9

Neurocrine (vagus/enteric reflexes
Endocrine (gastrin)
Paracrine (histamine)

Question 10

What is the stimulus for the vagal/enteric reflexes to release ACh

Answer 10

Distension of stomach (the arrival of food)

Question 11

What is the stimulus for the G cells to release gastrin?

Answer 11

Peptides in the lumen

Question 12

What are the stimuli (2) for the ECL cells to release histamine?

Answer 12

Gastrin

ACh

Question 13

What are the 3 phases of gastric acid secretion?

Answer 13

Cephalic phase
Gastric phase
Intestinal phase

Question 14

How can gastric secretion be inhibited in the cephalic phase and why?

Answer 14

By stopping eating - Decreases vagal activity

Question 15

How can gastric secretion be inhibited in the gastric phase and why?

Answer 15

By decreasing the pH (and therefore increasing HCl) - Decreases gastrin secretion

Question 16

What are enterogastrones?

Answer 16

Hormones secreted by gland cells in the duodenal mucosa

Question 17

Give 3 examples of enterogastrones?

Answer 17

Secretin
Cholecystokinin (CCK)
Gastric inhibitory polypeptide (GIP)

Question 18

The presence of what 4 substances in the duodenum would cause enterogastrones to be released?

Answer 18

Acid
Hypertonic solutions
Fatty acids
Monoglycerides

Question 19

What is the collective function of all enterogastrones?

Answer 19

To prevent further acid build-up in the duodenum

Question 20

What 2 methods are used by enterogastrones to prevent further acid build up in the duodenum?

Answer 20

Inhibit gastric acid secretion

Reduce gastric emptying (by inhibiting the motility of the pyloric sphincter)

Question 21

What is pepsinogen an inactive precursor for?

Answer 21

Pepsin

Question 22

What is a zymogen?

Answer 22

An inactive precursor of an enzyme?

Question 23

Why is zymogen storage important?

Answer 23

Prevents cellular digestion

Question 24

How is pepsinogen activated?

Answer 24

When released into a low pH (>3)

Question 25

When is pepsin inactivated?

Answer 25

At a neutral pH (7)

Question 26

What type of role does gastric mucus have?

Answer 26

A Cytoprotective Role

Question 27

What are the 2 functions of gastric mucus?

Answer 27

Protect mucosal surface from mechanical injury

Protect agains gastric acid corrosion and pepsin digestion (via neutral pH HCO3)

Question 28

What is intrinsic required for?

Answer 28

Vitamin B12 absorption to form complex

Question 29

Where is the intrinsic factor/B12 complex absorbed from?

Answer 29

The ileum

Question 30

What condition can a lack of intrinsic factor lead to?

Answer 30

Pernicious anaemia