GI 3 Part 2

Question 1

How many litres of food, drink, saliva enter stomach each day

Answer 1

3.5 litres

Question 2

Stomachs 3 general functions

Answer 2

1. Storage
2. Digestion
3. Defence

Question 3

What is storage in stomach for

Answer 3

To regulate passage into small intestine

Question 4

What is digestion in the stomach

Answer 4

Chemical and mechanical digestion into chyme using peristaltic contractions

Question 5

What does defence do in stomach

Answer 5

Destroys bacteria and other pathogens in food and other pathogens trapped in airway mucus (mucocilliary escalator)

Question 6

What is reinforced in stomach

Answer 6

Motility and secretion that was initiated during cephalic phase is driven by distension

Question 7

What enhances motility and secretions in the stomach

Answer 7

Distension

Question 8

Upon swallowing food what makes room in stomach for food

Answer 8

Parasympathetic neurons to ENS cause fundus of stomach to relax (receptive relaxation)

Question 9

What causes motility in stomach

Answer 9

Weak peristaltic waves (15-25 secs) that increase in force proceeding down antrum moves chyme toward pylorus (propulsion) and then larger particles are moved back to body (retropulsion)

Question 10

What does the peristaltic contractions in stomach cause

Answer 10

Mixes food with acid and digestive enzymes, small amounts of chyme squeeze through pylorus

Question 11

What do gastric secretions do

Answer 11

Protect and digest

Question 12

How are gastric secretions released with short reflex

Answer 12

G-cells release gastric (hormone) in response to amino acids, peptide, and distension

Question 13

What is long reflex of how gastric secretions released

Answer 13

Parasympathetic neurons to ENS and stimulate gastric production during cephalic phase

Question 14

How does gastrin directly stimulate gastric secretions

Answer 14

Stimulates gastric acid production and secretion directly from parietal cells

Question 15

What reflex for gastric secretions comes first

Answer 15

Long reflex and then short reflex causes further when food enters stomach

Question 16

How does gastrin indirectly stimulate parietal cells

Answer 16

Stimulates histamine release from enterochromaffin-like cells (ECL) which stimulates parietal

Question 17

Where is acid secretion from

Answer 17

Parietal cells

Question 18

How much gastric acid (HCl) produced daily

Answer 18

1-3 L with pH as low as 1

Question 19

What is parietal cells stimulated by

Answer 19

• gastrin from Gcells
• histamine from enterochromaffin-like cells
• ACh from ENS neurons via long and short reflexes (during cephalic)

Question 20

What are 5 gastric acid functions

Answer 20

1. Stimulated release of Pepsinogen from chief cells, cleaves pepsinogen to pepsin
2. Denatures proteins making easier for pepsin
3. Kills bacteria and other ingested microorganisms
4. Inactivates amylase from saliva
5. Stimulates D cells to release somatostatin

Question 21

What does pepsin do

Answer 21

Digest proteins