The GIT part 1

Question 1

Are substances of GIT tract outside or inside the body

Answer 1

Outside

Question 2

Where does the sympathetic and parasympathetic output come from

Answer 2

The CNS

Question 3

Function of chemoreceptors

Answer 3

Monitor O2, CO2 and pH levels

Question 4

Function of osmoreceptors

Answer 4

Monitor osmotic levels and maintain fluid homeostasis

Question 5

Function of mechanoreceptors

Answer 5

Detect stimuli such as touch, pressure, vibration and sound

Question 6

Intrinsic factors of control of gut function

Answer 6

Submucosal nerve plexus - regulates glandular and mucosal secretions
Myenteric plexus - controls gut wall contractions and gut motility

Question 7

Extrinsic factors of control of gut function

Answer 7

Parasympathetic - enhances gut motility and secretion

Sympathetic -inhibits gut motility and secretion

Question 8

What is the lining of the mucosa called

Answer 8

Muscularis mucosa

Question 9

Function of meissners plexus (submucosal plexus)

Answer 9

Enteric nervous system - major nerve supply to GI tract, controls glandular secretions and GI tract motility - SECRETIONS

Question 10

Function of Auerbach’s plexus (myenteric plexus)

Answer 10

Controls GIT movements and motility - MOVEMENT

Question 11

Function of cholecytoskinin

Answer 11

Stimulates production of bile in liver and release of bile in the gall bladder

Question 12

Function of gastrin

Answer 12

Stimulates gastric acid secretion and gastric mucosal epithelium proliferation - peptides and amino acids in gastric lumen released

Question 13

Function of secretin

Answer 13

Stimulates secretion of water and bicarbonate from the pancreas and bile ducts - causes a low pH in small intestine

Question 14

Function of ghrelin

Answer 14

Stimulates appetite, increases gastric emptying and stimulate growth hormone secretion

Question 15

Function of motilin

Answer 15

Stimulates small intestine motility

Question 16

Function of GIP

Answer 16

Inhibits gastrin secretion and motility, potentiates release of insulin from beta cells in response to elevated blood glucose

Question 17

What is the important thing that the stomach produces

Answer 17

Intrinsic factor - glycoprotein required for absorption of vitamin B12 in the small intestine

Question 18

What cells does the cardia produce

Answer 18

Mucus secreting cells (goblet cells)

Question 19

What cells does the fundus (body) produce

Answer 19

acid producing parietal cells

pepsin producing chief cells

Question 20

What cells does the pylorus produce

Answer 20

hormone (gastrin production)

Question 21

What is secreted by the parietal cells

Answer 21

HCl secretion (by active transport) regulated by H2 histamine receptors

Question 22

What does chief cells produce

Answer 22

Pepsinogen to pepsin and gastric lipases

Question 23

Function of APUD cells (enteroendocrine)

Answer 23

G cells: gastrin secreting
D cells: produce somatostain
ECL cells: secrete histamine

Question 24

What is the intrinsic factor synthesised by

Answer 24

Gastric parietal cells

Question 25

What does failure of B12 absorption lead to

Answer 25

Pernicious anaemia

Question 26

Stages of digestion in the stomach

Answer 26

Cephalic phase
Gastric phase
Intestinal phase (basal phase)

Question 27

What happens in the cephalic phase

Answer 27

Stimulation - CNS response to presentation of food, enhances gastric gland secretion

Inhibition - loss of appetite, satiety and depression

Question 28

What happens in the gastric phase

Answer 28

Food enters the stomach: stretch, increase pH and peptides : these cause gastric gland secretion

Question 29

What happens in the intestinal phase

Answer 29

As chyme enters the duodenum the mucosa secretes enteric gastrin which stimulates secretion by gastrin glands. As more chyme fills the small intestine the ‘enter gastric reflex is triggered’

Question 30

Function of ranitidine

Answer 30

H2 blocker

Prevent and treat heartburn