15.7 Biochemistry: Bile Flashcards
What produces bile? Why?
Liver, to assist digestion
What colour is bile/gall?
Dark green. yellowish-brown fluid (bitter tasting)
What secretes bile into the caniliculi?
Hepatocytes
What do epithelial cells do to the bile?
Add bicarbonate to dilute and increase alkalinity of the bile
Where is bile stored?
Gall bladder
What hormone regulates gall bladder function?
Cholecystokinin
What happens in the absence of bile?
Fats become indigestible, excreted in faeces (white, grey, greasy)
How much bile can the human liver produce?
1L a day (depending on body size)
What are bile salts?
Steroid structures, with a carboxylic acid group that is commonly linked to glycine or taurine to increase solubility
What are the most important bile acids?
Cholic acid
Doxycholic acid
Chenodeoxycholic acid
What proportion of bile salts are reabsorbed? Where? What is this process called?
95% reabsorbed in the terminal ileum, called ‘enterohepatic circulation’
What do pancreatic secretions contain?
Bicarbonate (duct cells)
Enzymes (acinar cells)
What are pancreatic enzymes synthesised as?
Zymogens
What are some pancreatic zymogens that become functional in the intestine? (6)
Trypsinogen Chymotrypsinogen Proelastase Procarboxypeptidase Pancreatic lipase Amylase
What is the acidity/alkalinity of pancreatic juice?
Alkaline (due to HCO3)
Useful in neutralizing acid (enzyme action)
What hormones regulate pancreatic secretion?
Secretin and cholecystokinin (produced by the walls of the duodenum)
What does CCK stimulate?
Gall bladder contraction
Digestive enzyme production (pancreas)
Release of insulin (islets)
What does CCK also contribute to?
Satiety
When is bile released from the gallbladder?
In response to food (into the small intestine via the sphincter of Oddi)
What are bile pigments the breakdown products of?
Hb (mostly bilirubin diglucuronide)
What are bile salts derivatives of?
Detergent derivatives of cholesterol
What gives faces its colour?
Bilirubin and its microbial modified forms
What does lipase produce?
Fatty acids
Monacyglycerols
Diacyl glycerols
What can steatorrhea lead to?
Deficiencies in essential fatty acids and fat-soluble vitamins
How can an artificial steatorrhea be created?
Using Orlistat (Xenical) to reduce fat absorption in the obese
What are the two main causes of pancreatitis?
Alcohol abuse and gallstones
What is elevated in pancreatitis?
Serum amylase and/or lipase (lipase is more specific)
