Nutrient absorption and transit

Question 1

what prevents chyme moving from stomach to the duodenum

Answer 1

pylorus sphincter

Question 2

what hormones prevent the pylorus sphincter opening

Answer 2

secretin

cholecystokinin

Question 3

exocrine pancreas function

Answer 3

provides main digestive fluid of small intestine

empties into duodenum via pancreatic duct/common bile duct

Question 4

what does the pancreatic secretion consist of

Answer 4

water
bicarbonate
enzymes

Question 5

what is the function of the bicarbonate in the pancreatic secretion

Answer 5

neutralises acid in chyme

Question 6

what are the enzymes in the pancreatic secretion

Answer 6

trypsin(OGEN)
chymotrypsin(OGEN)
amylase
lipase
nuclease
STORED INACTIVE - ZYMOGENS

Question 7

when are the enzymes from the pancreatic secretion activated

Answer 7

when reach duodenum

Question 8

what is the function of trypsin(ogen) enzyme in pancreatic secretion

Answer 8

‘chop’ different points of polypeptide chains

Question 9

what is the function of lipase in the pancreatic secretion

Answer 9

break down fat

Question 10

what is the function of amylase in the pancreatic secretion

Answer 10

polysaccharide digestion

Question 11

what is the function of nuclease in the pancreatic secreiton

Answer 11

break all nucleic acids

Question 12

what is the function of chymotrypsin(ogen) in the pancreatic secretion

Answer 12

‘chop’ different point on polypeptide chains

Question 13

what is involved in the neurological control of the pancreas

Answer 13

parasympathetic nerves

• acetylcholine
• vasoactive intestinal peptide

Question 14

what is involved in the hormonal control of the pancreas

Answer 14

secretin (made in response to acid, it causes response to release bicarbonate)
cholecystokinin (made in response to fats/amino acids)

Question 15

what does synergistic mean in relation to the neurological and hormonal stimulatory factors

Answer 15

they work better when both in action

Question 16

how is trypsin activated

Answer 16

trypsinogen (inactive precursor) contact with mucosa lining in duodenum
enterokinase (intestinal brush border) enzyme cuts off inactive part of trypsinogen
trypsin catalyses conversion of all other enzyme precursors to active

Question 17

what is the third site of infection protection

Answer 17

immune cells in liver

Question 18

how many litres of bile are made per day and where is it produced

Answer 18

0.7-1.2 litres a day

in the liver

Question 19

where is bile stored

Answer 19

gall bladder

Question 20

how is bile used in digestion

Answer 20

emulsifying agent - fat absorption aider

Question 21

what is bile mainly made up of

Answer 21

mainly made of cholic acid and chenodeoxycholic acid

can contain cholesterol and lecithin

Question 22

an example of bile - excretory

Answer 22

breakdown products of metabolism
e.g. haemoglobin, break down products are bile pigments
biliverdin (green)
bilirubin (red)
they’re converted to stercobilin (brown) (also use bacteria)

Question 23

what is the release of bile dependent on

Answer 23

cholecystokinin - causes the bladder contraction and relaxation of sphincter of oddi

Question 24

how can a fat molecule pass through the ‘unstirred’ layer - aqueous and acidic
what must happen when inside

Answer 24

when bile salts form around 
- hydrophilic tail attaches to fat 
- hydrophobic head 
form micelles, diffuse through
need to have contact with the villus tip so nutrients absorbed