15.7 Biochemistry: Bile

Question 1

What produces bile? Why?

Answer 1

Liver, to assist digestion

Question 2

What colour is bile/gall?

Answer 2

Dark green. yellowish-brown fluid (bitter tasting)

Question 3

What secretes bile into the caniliculi?

Answer 3

Hepatocytes

Question 4

What do epithelial cells do to the bile?

Answer 4

Add bicarbonate to dilute and increase alkalinity of the bile

Question 5

Where is bile stored?

Answer 5

Gall bladder

Question 6

What hormone regulates gall bladder function?

Answer 6

Cholecystokinin

Question 7

What happens in the absence of bile?

Answer 7

Fats become indigestible, excreted in faeces (white, grey, greasy)

Question 8

How much bile can the human liver produce?

Answer 8

1L a day (depending on body size)

Question 9

What are bile salts?

Answer 9

Steroid structures, with a carboxylic acid group that is commonly linked to glycine or taurine to increase solubility

Question 10

What are the most important bile acids?

Answer 10

Cholic acid
Doxycholic acid
Chenodeoxycholic acid

Question 11

What proportion of bile salts are reabsorbed? Where? What is this process called?

Answer 11

95% reabsorbed in the terminal ileum, called ‘enterohepatic circulation’

Question 12

What do pancreatic secretions contain?

Answer 12

Bicarbonate (duct cells)

Enzymes (acinar cells)

Question 13

What are pancreatic enzymes synthesised as?

Answer 13

Zymogens

Question 14

What are some pancreatic zymogens that become functional in the intestine? (6)

Answer 14

Trypsinogen
Chymotrypsinogen
Proelastase
Procarboxypeptidase
Pancreatic lipase
Amylase

Question 15

What is the acidity/alkalinity of pancreatic juice?

Answer 15

Alkaline (due to HCO3)

Useful in neutralizing acid (enzyme action)

Question 16

What hormones regulate pancreatic secretion?

Answer 16

Secretin and cholecystokinin (produced by the walls of the duodenum)

Question 17

What does CCK stimulate?

Answer 17

Gall bladder contraction
Digestive enzyme production (pancreas)
Release of insulin (islets)

Question 18

What does CCK also contribute to?

Answer 18

Satiety

Question 19

When is bile released from the gallbladder?

Answer 19

In response to food (into the small intestine via the sphincter of Oddi)

Question 20

What are bile pigments the breakdown products of?

Answer 20

Hb (mostly bilirubin diglucuronide)

Question 21

What are bile salts derivatives of?

Answer 21

Detergent derivatives of cholesterol

Question 22

What gives faces its colour?

Answer 22

Bilirubin and its microbial modified forms

Question 23

What does lipase produce?

Answer 23

Fatty acids
Monacyglycerols
Diacyl glycerols

Question 24

What can steatorrhea lead to?

Answer 24

Deficiencies in essential fatty acids and fat-soluble vitamins

Question 25

How can an artificial steatorrhea be created?

Answer 25

Using Orlistat (Xenical) to reduce fat absorption in the obese

Question 26

What are the two main causes of pancreatitis?

Answer 26

Alcohol abuse and gallstones

Question 27

What is elevated in pancreatitis?

Answer 27

Serum amylase and/or lipase (lipase is more specific)