S6.1 Pancreas And Liver Flashcards
Describe the composition of chyme that enters and leaves the duodenum.
Chyme which enters is hypertonic as the stomach is impermeable to water.
Chyme which leaves the duodenum is isotonic as the duodenum is permeable to water, as well as from liver and pancreas secretions
Duodenum secretes secretin and CCK in response to presence of chyme, what is the role of secretin?
Acts on the pancreas to stimulate HCO3- release
Duodenum secretes secretin and CCK in response to presence of chyme, what is the role of CCK?
CCK acts on pancreas to stimulate release of enzymes
CCK also contracts gallbladder and relaxes sphincter of oddi.
How do pancreatic secretions enter the duodenum?
Through the pancreatic duct then the ampulla of Vater (controlled by sphincter of Oddi).
What is the effect of a gallstone blocking the ampulla of vater?
Can lead to pancreatitis as the pancreatic protease secretions shall build up and become activated, digesting the pancreas.
Other than gallstones, name another cause of pancreatitis
Alcohol
What are the main cells of the pancreas?
Acinar cells
Duct cells
What is the function of acinar cells?
Stimulated by CCK when fats are detected in the duodenum, to release enzymes;
Amylase and lipase for fat
Proteases (inactive)
What is the function of duct cells in the pancreas?
Controlled by secretin when low pH detected in duodenum, releases HCO3-
The liver secretes bile in response to chyme, what is its role?
Bile emulsifies fat in duodenum so they can be readily digested by lipases secreted by pancreas.
Which area of the liver acinus is most susceptible to hypoxic damage?
Zone 3 because it’s furthest from the portal triads and thus low oxygen supply.
Zone 1 is more susceptible to toxic damage since its nearest triad so gets toxins carried in HPV.
What is the composition of bile?
Bile acids, bile pigments, alkaline solution, bilirubin
What are bile acids and salts?
Bile acid eg cholic acid, conjugates with amino acids to form bile salts, that help to emulsify fats
Briefly summarise how bile digests fats
Bile salts emulsify lipids into smaller molecules.
Bile salts form micelles so the lipids can enter the intestines enterocytes.
In the intestine the lipid molecules are re-esterified.
Reformed lipids are made into chylomicrons which are exocytosed from the enterocytes
What causes steatorrhoea?
Bile acids/salts or pancreatic lipases are not secreted in sufficient quantities, undigested fat appears in faeces.
