Gut L4

Question 1

absorption of glucose (aa and fa) from the duodenum stimulates what

Answer 1

pancreatic exocrine secretion via release of hormones CCK and secretin

Question 2

give 3 examples of brush border enzymes

Answer 2

sucrase
lactase
glucoamylase+a-dextrinase/sucrase

Question 3

which sugars can be absorbed

Answer 3

glucose
galactose
fructose

Question 4

how is starch or glycogen digested at the brush border

Answer 4

• a-amylase acts on it
• ~70% form alpha glucans with a 1,4 bond
• ~1/3rd form alpha glucans with a 1,6 bond
• these are further broken down by glucoamylase to form glucose
• sucrase and lactase broken down
• releases products close to plasma memb and transporters (SGLT1, GLUT5)

Question 5

how are monosaccharides uptaken

Answer 5

• via Na+/K+ pump, Na+ is constantly being taken into the enterocyte and into the SUBMUCOSA
• K+ is constantly being exchanged from submucosa and INTO cell O high pot conc, low Na conc
• after a meal, there is more LUMINAL Na+
• glucose enters cell via sodium glucose transporter
• high Na in lumen O moves into low conc of cell
• CO TRANSPORT of either glucose or galactose

Question 6

how does the body rapidly abs glucose

Answer 6

transiently GLUT2 is inserted into the apical membrane

• cuases secretion of INSULIN
• this process is REGUATED BY INSULIN

Question 7

who can absorb whole proteins
what is the importance of this
what is found in colostrum

Answer 7

in neonatal period (few days after birth)

• gives PASSIVE IMMUNITY from immunoglobulins in colostrum
• cont trypsin enzyme inhibitor O it is absorbed whole
• neonates don’t make gastric acid

Question 8

what do chief cells

Answer 8

releases pepsinogen and chymosin

Question 9

when is pepsingogen converted to pepsin

Answer 9

if pH less than 5

Question 10

the small peptides and aa released stimulate what

Answer 10

release of CHOLECYSTOKININ

Question 11

what does cholecystokinin do

Answer 11

a hormone which is secreted by cells in the duodenum and stimulates the release of bile into the intestine and the secretion of enzymes by the pancreas

Question 12

where is cholecystokinin released from

Answer 12

from pancreatic acinar cells

Question 13

give 3 examples of endopeptidases

Answer 13

trypsinogen
chymotrypsinogen
proelastase

Question 14

what converts trypsinogen to trypsin

where is it found

Answer 14

enterokinase

brush border peptidase

Question 15

what are the 3 phases of protein digestion by enzymes

Answer 15

1) luminal
2) membrane
3) cytoplasmic

Question 16

aminopeptidase is what kind of an enzyme

Answer 16

brush border enzyme

an EXOpeptidase

Question 17

carboxypeptidase is released from where

Answer 17

from pancreas

an EXOpeptidase

Question 18

what are the2 brush border peptidases

Answer 18

enterokinase (trypsinogen->trypsin)

aminopeptidase

Question 19

can small peptides be absorbed by adults

Answer 19

yep

Question 20

how are proteins absorbed

Answer 20

1) sodium amno acid coupled transport
2) Pept1- uses H+ co transporter
3) small chain of peptide enters vacuole and enters cell and enters blood

Question 21

how can proteins leave the cell and go to the blood

Answer 21

1) antiport movement with H+

2) broken down by INTRACELLULAR peptidase O liberate f.a.a and then leave via soidum coupled transport