Physiology

Question 1

What branch of the enteric nervous system controlls movement?

Answer 1

myenteric plexus

Question 2

What branch of the enteric nervous system controlls secretions?

Answer 2

submucous plexus

Question 3

Where is the enteric nervous system located?

Answer 3

myenteric: between longitudinal and circular muscle layers
submucous: between circular muscle and mucosa

Question 4

During peristalsis, what happens to muscles proximal to the bolus?

Answer 4

longitudinal realaxation, circular contraction

Question 5

During peristalsis, what happens to muscles distal to the bolus?

Answer 5

longitudinal contraction, circular relaxation

Question 6

What are the 7 GI sphincters?

Answer 6

UES, LES, pyloric, Oddi, ileocecal, internal anal, external anal

Question 7

What stimulates secondary peristalsis in the esophagus?

Answer 7

mechanoreceptors

Question 8

What are the 3 types of accomodation and their triggers?

Answer 8

receptive: mechanoreceptors in the pharynx
adaptive: vago-vagal by receptors in the stomach
feedback: nutrients in small intestine

Question 9

What is the order of nutrient emptying speed?

Answer 9

carb, protein, fat

Question 10

What is the interdigestive motility pattern in the small intestine?

Answer 10

migrating motor complex

Question 11

What is the purpose of the migrating motor complex?

Answer 11

move undigestable contents out of the small intestine

Question 12

What is the purpose of segmentation in the small intestine?

Answer 12

mixing and absorption of nutrients

Question 13

What are the 2 purposes of power propulsion?

Answer 13

clear out noxious substances from the bowels (leads to vomiting or diarrhea)
move contents form the distal colon to the rectum

Question 14

What is the purpose of haustration and where does it occur?

Answer 14

absorption of water in the large intestine

Question 15

What enzymes are secreted by salivary glands?

Answer 15

salivary amylase

lingual lipase

Question 16

What cells make up gastric glands, and what do they secrete? (5)

Answer 16

parietal cells - acid
ECL cells - histamine
chief cells - pepsinogen
G cells - gastrin
D cells - somatostatin

Question 17

What stimulates secretion of somatostatin and what does it do?

Answer 17

low pH; suppresses gastrin secretion

Question 18

What is the trigger for gastrin release and what does it do?

Answer 18

vagal stimulation via GRP

stimulates acid production

Question 19

What triggers CCK release, what cells produce it, and what does it do (3)?

Answer 19

nutrients in the duodenum
I cells (duodenum)
gallbladder contraction, sphincter of Oddi relaxation, pancreatic enzyme secretion

Question 20

Explain the CCK feedback loop

Answer 20

CCK causes release of pancreatic enzymes which break down food, releasing more nutrients, causing further CCK release

Question 21

What triggers secretin release, what cells produce it, and what does it do (3)?

Answer 21

protein and acid in duodenum
S cells in duodenum
stimulates bicarb release, augments CCK, decreases acid secretion

Question 22

How is bicarb secreted and from which cells?

Answer 22

CFTR pumps out Cl which is then exchanged for bicarb

duct cells

Question 23

What is the function of vasoactive intestinal peptide?

Answer 23

stimulates intestinal secretion of electrolytes adn H2O, stimulates release of NO to relax sphincters

Question 24

What is the function of motilin and where is it produced?

Answer 24

formation of migrating motor complexes

enterochromaffin cells

Question 25

What is the function of gastric inhibitory polypeptide and where is it produced?

Answer 25

less acid and more insulin | K cells of duodenum/jejunum

Question 26

What enzyme allows acid production?

Answer 26

carbonic anhydrase

Question 27

What are the triggers for acid secretion? (3)

Answer 27

gastrin ACh (vagus) histamine

Question 28

What is the main stimulus of acid secretion in the cephalic phase?

Answer 28

vagus

Question 29

What are the breakdown products of starch by pancreatic amylase?

Answer 29

disaccharides and alpha-limit dextrans

Question 30

What protein absorbs glucose?

Answer 30

SGLT-1 (Na-dependent)

Question 31

What protein absorbs fructose?

Answer 31

GLUT-5

Question 32

What protein absorbs galactose?

Answer 32

SGLT-1 (Na-dependent)

Question 33

What protein allows absorption of sugars out of enterocytes?

Answer 33

GLUT-2

Question 34

How is pepsinogen activated?

Answer 34

autolytic cleavage in the stomach

Question 35

What does pepsin target?

Answer 35

neutral amino acids of peptides in the stomach

Question 36

What is the difference between endopeptidases and exopeptidases?

Answer 36

endo: cleave internal bonds exo: free terminal amino acids

Question 37

What activates pancreatic zymogens?

Answer 37

trypsin

Question 38

What activates trypsinogen?

Answer 38

enterokinase

Question 39

Where is enterokinase found?

Answer 39

apical membrane of duodenal enterocytes

Question 40

How are oligopeptides absorbed?

Answer 40

non-specific transporter with H+ gradient

Question 41

How are amino acids absorbed?

Answer 41

specific transporters with Na+ gradient

Question 42

Where does emulsification of fats begin?

Answer 42

stomach

Question 43

What constituents of bile allow fats to be dissolved?

Answer 43

bile salts and lecithin

Question 44

What is the difference between gastric and pancreatic lipase?

Answer 44

gastric: cleaves one ester, low pH pancreatic: cleaves both sides, higher pH

Question 45

What is the function of colipase?

Answer 45

lipases are inhibited by bile. colipase binds to lipase and bile salts which anchors the enzyme on the droplet

Question 46

What cleaves the middle fatty acid of a triglyceride?

Answer 46

phsopholipase A2 (with calcium)

Question 47

What is the function of cholesterol esterase?

Answer 47

triglyceride digestion, digestion of fat-soluble vitamins

Question 48

How do fatty acids move from micelles to the inside of enterocytes?

Answer 48

the unstirred water layer is acidic which promotes release of fatty acids which diffuse into the cell

Question 49

What happens to fats inside the enterocytes?

Answer 49

they reform triglycerides, which are packaged with cholesterol, phospholipds, and apoproteins to form chylomicrons