Session 5- Pancreas and Liver

Question 1

in what state does chyme enter the duodenum

Answer 1

hypertonic- increases as digestion takes place
acidic
partially digested

Question 2

what mechanism is used to neutalise the acidic chyme

Answer 2

water from ECF/Circulation

secretions from
-pancreas- enzymes, bicarbonate ions to neurealise stomach acid

Liver

• bicarbonate ions
• bile

Question 3

why is chyme hypertonic

Answer 3

food produces a lot of solutes that are dissolved in gastric juice

stomach wall is largely impermeable to water

Question 4

what state is chyme in when it leaves the duodenum

Answer 4

isotonic

Question 5

where are bile and pancreatic secretions secreted intothe duodenum

Answer 5

sphincter of oddi

Question 6

pancreatic innervation

Answer 6

sympathetic inhibits

parasympathetic
-vagus stimulates

hormones

Question 7

what are the majority pancreatic secretions

Answer 7

exocrine portion 90%

Question 8

what stimulates the acinus to produce secretions

Answer 8

vagus
cholecystokinin

hypetonicity
small peptides
fats detected in duodenum

Question 9

drainage of liver

Answer 9

cetral veins drain into hepatic veins which drain the liver

hepatic portal veins bring blood to the liver

Question 10

zones of acinus

Answer 10

zone 1= closest to portal triads
zone 3= closest to central vein

any toxins coming into liver affect zone 1 first

zone 3 is more likely to be affected by ischaemia- furthest away from blood coming in

Question 11

2 compenents of bile

Answer 11

bile acid dependant

• secreted into canaliculi by hepatocytes
• contains bile acids and pigments

bile acid independant

• secreted by duct cells
• similar alkaline solution to pancreatic duct cells
• stimulated by secretin

Question 12

what are the 2 primary bile acids

Answer 12

cholic acid

chenodeoxycholic acid

Question 13

what are bile salts

Answer 13

bile acids that are conjugated with the amino acids

• glycine
• taurine

Question 14

why do we use bile salts

Answer 14

they are generally active at duodenal pH

ampipathic structure
-crucial for emulsifcation of dietary lipids

Question 15

how are fats digested

Answer 15

bile acids emulsify fats into smalle runits
-increase SA for lipases to act

then form micelles with products of lipid breakdown

lipids diffuse down conc gradient into intestinal epithelial cell

inside cell re-esterfied back to

• triglycerides
• phospholipids
• cholesterol

reformed lipods packaged with apoproteins
-chylomicrons

exocytosis from basolateral membrane into lymph capillaries and re enter vascular circulation into the thoracic duct

Question 16

what are micelles

Answer 16

vehicles to carry hydrophobic molecules through an aqueous medium

Question 17

enterohepatic circulation of bile acids

Answer 17

bile salts dont enter gut epithelial cells woth lipids

• remain in gut lumen
• reabsorbed in termina ileum
• return to liver in portal blood
• liver extracts bile salts

liver reuses bile acid

Question 18

where is bile stored

Answer 18

gall bladder

concentrates it which can lead to gallstones

Question 19

what is steatorrhoea

Answer 19

fat in faeces if bile acids or pancreatic lipases are not secreted in adequate amounts