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PHSL233 > Lecture 30 - Regulation of Gastric Acid Secretion II > Flashcards

Lecture 30 - Regulation of Gastric Acid Secretion II Flashcards

1
Q

What signals the feedback inhibition of gastric acid secretion in the antral region?

A

Presence of H+ ions in lumen

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2
Q

What are the two sites of feedback inhibition for gastric acid secretion?

A

Body/corpus, which is site of acid secretion
Antral region, which is site of gastrin secretion

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3
Q

What is involved in feedback inhibition of gastric acid secretion?

A

Somatostatin

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4
Q

What does the presence of H+ ions lumen stimulate in the antral region of stomach?

A

Stimulates somatostatin secreting cells (D cells) to produce somatostatin

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5
Q

What can somatostatin act as?

A

Paracrine hormone
- inhibits gastrin production by G cells
Endocrine hormone
- inhibits parietal cells

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6
Q

What is the G cells stimulated by in the antral region?

A

Digested proteins and amino acids
GRP

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7
Q

What are D cells stimulated by in antral region?

A

Luminal acid (H+)
Gastrin

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8
Q

What are D cells inhibited by in antral region?

A

ACh

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9
Q

What are G cells inhibited by in antral region?

A

Somatostatin

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10
Q

What is the feedback inhibition of acid secretion from the antral region?

A

Inhibition of acid secretion by events in the antral region - endocrine action - somatostatin

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11
Q

What is the function of somatostatin cells in body/fundus of stomach?

A

To produce somatostatin to limit acid secretion

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12
Q

How does somatostatin act as paracrine hormone?

A
  • inhibits acid secretion by parietal cells
  • inhibits ECL cells so reduces histamine production
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13
Q

The feedback inhibition of gastric acid secretion is
A. mainly dependent on gastrin.
B. entirely based on paracrine feedback.
C. independent of the stomach body region.
D. mainly facilitated by somatostatin

A

D. mainly facilitated by somatostatin

B- endocrine feedback
C - Dependent on stomach body region

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14
Q

What is the basal rate of gastric secretion?

A

25mL per hour

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15
Q

How does the cephalic phase stimulate secretion?

A

Via the parasympathetic nervous system (PNS)

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16
Q

How does the PNS regulate acid secretion?

A

Via ENS which in turn:
Directly stimulates parietal cells
Stimulates release of gastrin from antral region to blood
Stimulates histamine release from ECL cells

17
Q

What controls gastric acid secretion in the gastric phase?

A

Stomach

18
Q

What do receptors in stomach respond to in gastric phase?

A

Stretch (distention)
Products of digestion (antrum)
- increased peptides, decreased H+

19
Q

How does stomach stimulate gastric acid secretion in gastric phase?

A

ENS - local reflex
External reflex involving the CNS (due to distention)
- vagovagal reflex
Gastrin and histamine

20
Q

What controls gastric acid secretion in the intestinal phase?

A

Intestine

21
Q

What is the effect of intestine control during the intestinal phase of gastric acid secretion?

A

Inhibit secretion via CCK, secretin and other duodenal hormones

22
Q

What does the intestine respond to in the regulation of gastric secretion?

A

Distension
Increased [H+], Osmolarity, [Nutrients]

23
Q

What is parallel to the secretion of gastric acid?

A

Secretion of pepsin

24
Q

Gastric acid secretion is
A. increased in the intestinal phase.
B. regulated by acid and digestion products in the duodenum.
C. mainly driven by sight, smell and thought.
D. independent of the cephalic phase.

A

B. regulated by acid and digestion products in the duodenum.
- Duodenum releases CCK which switch off G cells

A - decreased
C - Not just cephalic phase
D - Dependent

25
Q

What is released in intestinal phase regulation of gastric acid secretion?

A

CCK and secretin

PHSL233 (32 decks)

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