Gastric Secretion Flashcards Preview

Alimentary System > Gastric Secretion > Flashcards

Flashcards in Gastric Secretion Deck (40):
1

What are the three main functional parts of the stomach?

Fundus, body and antrum

2

What is the fundus of the stomach responsible for?

Storage

3

What are the functions of the body of the stomach?

Storage
Mucous production
HCl production
Pepsinogen production
Production of intrinsic factor

4

What are the functions of the antrum of the stomach?

Mixing and grinding of the stomach contents
Production of gastrin

5

What feature of the antrum aids the mixing and grinding of the stomach contents?

Very thick muscularis externae

6

Where is gastrin released and what does it do?

Released in the antrum, gastro-intestinal hormone which is secreted into stomach lumen, taken into circulation then returned to stimulate the stomach cells

7

What three mechanisms control gastric acid secretion?

Neurocrine - vagus nerve and local reflexes
Endocrine - gastrin
Paracrine - histamine

8

What is the first thing to prepare the stomach for digestion and what does this cause?

Precursors to eating - sight, smell and taste of food
Causes stomach to create acid which will instantly sterilise any bacteria ingested

9

What three things are stimulated by the vagus nerve or by gastrin in the cephalic phase to trigger acid production?

Stomach
G cells
ECL cells

10

When does the gastric phase occur?

Once there is a physical presence of food in the stomach

11

Distension of the stomach (gastric phase) triggers long reflexes from the _ and short reflexes from the _

Vagus nerve
Enteric reflexes

12

Vagus nerve and enteric reflexes trigger the release of

ACh

13

Peptides in the lumen stimulate

G cells which release gastrin

14

Gastrin and ACh can also stimulate the ECL cells which release

histamine

15

What will inhibit gastric acid secretion in the cephalic phase?

Absence of stimulus i.e. stop eating

16

What will inhibit gastric acid secretion in the gastric phase?

H ion increases, pH decreases leading to decreased gastrin release as environment is acidic enough

17

Pancreatic enzymes are extremely sensitive to

acid/low pH

18

Acid in the duodenum triggers

the enterogastric reflex and secretin release from the surface of the duodenum

19

Secretin triggers the release of

bicarbonate

20

Secretin and bicarbonate will cause

reduction in gastric secretion and therefore reduce the effect of gastrin stimulation on the parietal cells

21

Fat in the duodenum causes the release of _ which causes

gastric inhibitory peptide
causes reduced gastric secretion and reduced parietal HCl secretion

22

The intestinal phase occurs when

signals are sent that the stomach is emptying its contents

23

The intestinal phase reduces

acid damage to the duodenum

24

What is pepsinogen?

The zymogen of pepsin

25

What is a zymogen?

An inactive precursor of an enzyme

26

When is pepsinogen converted to pepsin?

When the pH is below 3

27

When are pepsins inactivated?

At neutral pH

28

Gastric motility causes the

mixing of the stomach contents, contraction of pyloric sphincter and further mixing

29

What is the function of the pyloric sphincter?

Controls passage of stomach contents into the duodenum

30

What are responsible for gastric motility?

Peristaltic waves

31

Where do peristaltic waves originate?

Oesophagus

32

Why are more powerful contractions possible once the peristaltic wave reaches the antrum and pyloric sphincter?

As the muscle here is thicker and more powerful

33

Does gastrin increase or decrease contraction in the stomach?

Increase

34

How is the stomach emptied?

Gradually

35

The presence of what in the duodenum will inhibit gastric motility?

Fat
Acid
Amino acids
Hypertonicity

36

What is the only essential, non-compensated function of the stomach?

Releasing intrinsic factor to form a complex with vitamin B12, allowing it to be absorbed from the ileum

37

What will a defect in intrinsic factor lead to?

Pernicious anaemia

38

What cells produce gastric mucous?

Surface epithelial cells and mucous neck cells

39

What role does gastric mucous have?

Cytoprotective role

40

What is the function of the high bicarbonate content of gastric mucous?

Neutralises the pH of gastric acid, completely denaturing pepsin and stopping the corrosive acid from reaching the cells below the mucous layer