GIT physiology

Question 1

what are migrating myoelectric complex stimulated by?
1. _____ (increase/decrease) in chyme pH
2. _____ (increase/decrease) in plasma [motilin]

Answer 1

1. increase in chyme pH
2. increase plasma [motilin]

Question 2

what is migrating myoelectric complex replaced by when a meal enters the stomach?

Answer 2

segmenting/mixing contractions

Question 3

what are the 3 phases of swallowing?

Answer 3

1. buccal (voluntary)
2. pharyngeal (involuntary)
3. oesophageal (involuntary)

Question 4

which part of the brain controls the buccal phase of swallowing?

Answer 4

cerebral cortex

Question 5

which part of the brain controls the pharyngeal and oesophageal phases of swallowing?

Answer 5

medulla (brainstem)

Question 6

what are the functions of migrating myoelectric complex?

Answer 6

1. move undigested remains to large intestine
2. prevent overgrowth of bacteria

Question 7

what are the 3 extrinsic salivary glands?

Answer 7

1. parotid gland (largest)
2. submandibular gland
3. sublingual gland (smallest)

Question 8

what is the function of mucin in the saliva?

Answer 8

lubrication of food

Question 9

what is the enzyme present in saliva for carbohydrate digestion?

Answer 9

amylase (ptyalin)

Question 10

what is ptyalism?

Answer 10

excessive salivation

Question 11

what is xerostomia?

Answer 11

dry mouth (insufficient salivation)

Question 12

what is the function of pepsin?

Answer 12

initiate protein digestion in stomach

Question 13

what is the function of intrinsic factor?

Answer 13

allows absorption of vitamin B12

Question 14

what do parietal cells secrete?

Answer 14

HCl and intrinsic factor

Question 15

what do chief cells secrete?

Answer 15

pepsinogen

Question 16

what do enterochromaffin-like cells secrete?

Answer 16

histamine

Question 17

what do G cells secrete?

Answer 17

gastrin

Question 18

what do D cells secrete?

Answer 18

somatostatin

Question 19

what are the 4 types of secretory cells in gastric glands?

Answer 19

1. mucus cells
2. parietal cells
3. chief cells
4. enteroendocrine cells

Question 20

why can’t unconjugated bilirubin be renally excreted?

Answer 20

it is not water soluble; fat soluble

Question 21

what is the function of bile salts?

Answer 21

emulsify fats in small intestine

Question 22

what is lecithin?

Answer 22

phospholipid that combines with bile salts to emulsify fats

Question 23

what do acinar cells of the pancreas secrete?

Answer 23

pancreatic enzymes (synthesised in zymogen granules)

Question 24

which enzyme initiates activation of pancreatic enzymes?

Answer 24

membrane-bound enterokinase

Question 25

what enzyme converts trypsinogen to trypsin?

Answer 25

enterokinase

Question 26

what hormone is released in response to fat and protein in the duodenum?

Answer 26

cholecystokinin

Question 27

what do acinar cells secrete in response to increase cholecystokinin?

Answer 27

digestive pancreatic enzymes

Question 28

what stimulates ductal cells of the pancreas to increase bicarbonate secretion?

Answer 28

increase secretin in response to acidic chyme

Question 29

what type of jaundice would have normal urine and stool colour?

Answer 29

pre-hepatic jaundice

Question 30

what type of jaundice presents with dark urine and pale stools?

Answer 30

cholestatic/post-hepatic jaundice

Question 31

what type of jaundice presents with dark urine and normal stools?

Answer 31

mixed/intra-hepatic jaundice

Question 32

which part of the hypothalamus controls appetite?

Answer 32

arcuate nucleus

Question 33

does ghrelin promote or inhibit hunger?

Answer 33

promote

Question 34

which hormone inhibits hunger?

Answer 34

leptin

Question 35

what is required for the activation of pepsin from pepsinogen?

Answer 35

HCl to achieve optimal pH2

Question 36

what types of contractions are triggered by the filling of your stomach?

Answer 36

segmenting contractions (small intestine)
mass movements (large intestine)

Question 37

what are the main substances absorbed in the duodenum, jejunum and ileum?

Answer 37

duodenum: iron
jejunum: folate
ileum: vitamin b12

Question 38

Which of the following mediators can suppress gastrin/histamine regulation of gastric acid secretion?

a. prostaglandin
b. dopamine
c. ACh
d. amoxicillin

Answer 38

prostaglandin

prostaglandin and somatostatin inhibits gastric acid secretion

Question 39

Which of the following enzymes does the pancreas secrete in its inactive (precursor) state?

a. cholesterol elastase
b. chymotrypsin
c. lipase
d. amylase

Answer 39

b. chymotrypsin