Lipid Digestion FC

Question 1

Questions

Answer 1

Answers

Question 2

What breaks down fatty acids? From what? Which positions?

Answer 2

Lipases
Triglycerol
From positions 1 and 3

Question 3

What lipase is made in the mouth? Does it remain active in the stomach?

Answer 3

Lingual Lipase

Yes

Question 4

Why do lipases only have limited activity without stomach churnning?

Answer 4

Because they can only act on the surface area of a lipid droplet

Question 5

What secretes gastric lipase?

Answer 5

Gastric mucosa

Question 6

Which lipase does most triacylglyceral hydrolysis?

Answer 6

Pancreatic lipase

Question 7

Besides pancreatic lipase, what else is secreted by the pancreas with the lipase? What is its function?

Answer 7

Procolipase - proenzyme
Converted to colipase by trypsin
Colipase binds lipace to mixed micelle, prevent inhibition of lipase by bile salts

Question 8

What are the two major products of lipase?

Answer 8

2 FFA

1 2-monoacylglycerol

Question 9

What two other ezymes are released from the pancreas to aid in lipid metabolism? What is their function?

Answer 9

Prophospholipase A2 - converted to phospholipase A2 by trypsin, then removes FA from 2nd position, producing one FFA and one lysophosphlipid
Choslesterol esterase - hydrolyzes ester producing cholesterol and FFA

Question 10

Which fatty acids do not require bile salts to be absorbed?

Answer 10

Short/medium chain bile salts

Question 11

Which 3 proteins play a role in sterol absorption?

Answer 11

NPC1L1 - Niemann-Pick C1-like protein
SCARB1 - scavender receptor B-1
CD36

Question 12

What happens if NPC1L1 is knocked out?

Answer 12

70% decrease in cholesterol absorption

Question 13

What percentage of dietary cholesterol is absorbed?

Answer 13

30-40%

Question 14

What percentage of FFA and MAGs are absorbed?

Answer 14

Nearly 100%

Question 15

What binds with long chained fatty acids inside intestinal cells?

Answer 15

Fatty acid-binding protein (FAB)

Question 16

Where in the cell are fatty acids converted to triacylglycerols?

Answer 16

ER

Question 17

Which pathway contributes to most triacylglycerol synthesis? What two enzymes are used?

Answer 17

Monoacylglycerol Pathway

Monoacylglycerol acyltransferase and diacylgycerol acyltransferase

Question 18

What is a secondary pathway for triacylglycerol synthesis? What enzyme is used first? Which enzyme can be used from the monoacylglycerol pathway and when?

Answer 18

Phosphatidic acid pathway
Glycerol kinase
Diacylglycerol acyltransferase - adds 3rd acyl after the phosphate group has been removed from 3rd position

Question 19

What are the two components of a chylomicron? Where are chylomicrons secreted?

Answer 19

Reassembled lipids and APO-lipoprotein

Into lymph

Question 20

What color will stool be when there is insufficient Bile? Where there is insufficient pancreatic enzymes?

Answer 20

Light/clay colored

Normal

Question 21

What two enzymes does Orlistat inhibit? What does this cause? Side effects are similar to what disorder?

Answer 21

Inhibits gastric and pancreatic lipase
Reduces fat absorption
Steatorrhea

Question 22

What is Olestra? How does it interact with lipase? What supplement must be given?

Answer 22

Fatty acyl resistant to lipase (taste and consistency of fat)
Supplement fat soluble vitamens

Question 23

What does Ezetimibe inhibit? What does this decrease?

Answer 23

Inhibits NPC1L1

Deccreases cholesterol absorption