Lecture 30

Question 1

Why is it necessary to reduce the pH of the chyme?

Answer 1

to allow the local enzymes to function and to prevent the duodenum from ingesting itself

Question 2

What are the three proteolytic enzymes?

Answer 2

Trypsin (ogen), Chymotrypsin (ogen), (Pro) carboxypeptidase

Question 3

What are the amylolytic enzymes?

Answer 3

Alpha-amylase

Question 4

What are the lipolytic enzymes?

Answer 4

Lipase

Question 5

What is the process by which the three proteolytic enzymes are activated?

Answer 5

1. Enzyme is secreted in an inactive form, trypsinogen is activated to trypsin by enterokinase, trypsin then activates the other two enzymes 2. Trypsin and chymotrypsin split the proteins into peptides (but not individual amino acids) 3. Carboxypeptidase- splits some proteins into individual amino acids

Question 6

What are the general functions of the enzyme amylase?

Answer 6

• secreted by the pancreas and salivary glands - digests starch forming maltose and maltotriose - complete hydrolysis produces monosaccharides - stimulated by diets that are high in starch

Question 7

What are the general functions of the enzymes lipase?

Answer 7

• involved in fa digestion but bile salts from within the live are also required - hydrolysis of fat allows formation of water-soluble micelles - lipase secretion is stimulated by diets that are high in fat

Question 8

Name the blank ion in the table below

Answer 8

1. bicarbonate ion

Question 9

What are the two main sources that the liver receives blood from?

Answer 9

The liver recieves blood from both the hepatic artery and the portal vein

Question 10

Describe the pathway of bile acids around the body:

Answer 10

1. Bile acids are conjugated either with taurine and glycine and are then excreted in the bile
2. Reduces the pK, so bile acids exist as bile salts
3. Bile acids are not fat soluble, so tend to remain in the lumen of the small intestine
4. Carry out role in formation of micelles (fat absorption)
5. Re-absorbed by active process in distal ileum or degraded to secondary bile acids by intestinal bacteria
6. 95% re-absorbed to liver via portal circulation

Question 11

What substances are re-absorbed within the gall bladder?

Answer 11

sodium, chloride and bicarbonate followed by the passive re-absorption of water

Question 12

What are the three main components of the portal triad?

Answer 12

the hepatic artery, portal vein, bile duct

Question 13

What is the name of the blood flow in the middle of a classic hepatic lobule?

Answer 13

the central vein

Question 14

What is the name of the main bile salt and what is it’s precursor molecule?

Answer 14

Cholic acid (comes from cholesterol)

Question 15

Name each of the following components in the diagram below:

Answer 15

1. blood vessel
2. intercalated duct
3. acinar cells
4. centroacinar cells (dont need to know