Lipid Digestion and Absorption

Question 1

How many grams of lipids do adults consume?

Answer 1

• about 81g
• 90% TAG
• 10%
  
  • cholesterol
  • cholesterol esters
  • phospholipids
  • free fatty acids

Question 2

Acid Lipase

Answer 2

acid-stable lipases function in the stomach at optimal pH between pH 4 and 6

• want to break ester bonds
• lingual lipase
• gastric lipase
• target TAG containing short and medium chain FA (milk fat)
• important in neonates

Question 3

lingual lipases

Answer 3

• acid lipase
• secreted rom glands at back of tongue
• wants to break ester bonds

Question 4

gastric lipase

Answer 4

• acid lipase
• secreted from the gastric mucosa
• wants to break ester bonds

Question 5

emulsification of lipids

Answer 5

-small intestine

two complimentary actions:

• mechanical agitation
• bile salts secretion

Question 6

mechanical agitation in emulsification of lipids

Answer 6

-dietary material via peristalsis increases the lipid droplet surface area

Question 7

Bile salts secretion in emulsification of lipids

Answer 7

• made in liver
• stored in gallbladder
• secreted into small intestine
• detergent properties

Question 8

detergent properties of bile salts

Answer 8

stabilize particles as they become smaller, prevents them from coalescing

Question 9

components of bile

Answer 9

glycine and colic acid

Question 10

pancreatic enzymes

Answer 10

secreted from the pancreas digest dietary TAG, cholesterol esters and phospholipids

Question 11

digestion

Answer 11

the removal of specific FA by breaking ester bonds attaching the FA

Question 12

What are some pancreatic enzymes?

Answer 12

• pancreatic lipase
• colipase
• cholesterol esterase
• phospholipase A2
• lysophospholipase

Question 13

pancreatic enzymes responsible for TAG digestive

Answer 13

• pancreatic lipase

- colipase

Question 14

pancreatic enzymes responsible for cholesterol ester digestion

Answer 14

-cholesterol esterase

Question 15

pancreatic enzymes responsible for phospholipid digestions

Answer 15

• phospholipase A2

- lysophospholipase

Question 16

TAG digestions

Answer 16

too big for intestinal mucosal cells to endocytose efficiently

Question 17

pancreatic lipase

Answer 17

• pancreatic enzyme
• digestion of TAG
• cleaves FA of glycerol backbone
• produces 2 free FA
• 1 2-monoacylclycerol
• 2-3% total protein in pancreatic secretions
• VERY HIGH catalytic efficiency

Question 18

colipase

Answer 18

• pancreatic enzyme
• TAG digestion
• binds pancreatic lipase at a 1:1 ratio
• promotes pancreatic lipase activity when inhibitory bile salts are present

Question 19

cholesterol esteras

Answer 19

• pancreatic enzyme
• cholesteryl ester digestion
• 10-15% (esterified cholesterol)
• digests esterified cholesterol

Question 20

Phospholipase A2

Answer 20

• pancreatic enzyme
• phospholipid digestion
• removes FA to produce lysophospholipid and a free fA

Question 21

lysophospholipase

Answer 21

• pancreatic enzyme

- phospholipid digestion

Question 22

Gut endocrine cells

Answer 22

sense:
-lipids and partially digested proteins
-the low pH of chyme entering the intestines
Secrete:
-CCK
-secretin

Question 23

CCK

Answer 23

-hormone secreted in response to presence of lipids and partially digested proteins

promotes:

• bile salts
• phospholipids
• free cholesterol

decreases:

• gastric motilitly
• reducing release of gastric contents

Question 24

secretin

Answer 24

-hormone secreted in response to the low pH of chyme entering the intestine

promotes:
-bicarbonate, makes alkaline

Question 25

micelles

Answer 25

- disk shaped clusters of amphipathic lipids | - formed from these three products, bile salts, and fat soluble vitamins (K,A,D,E)

Question 26

Enterocytes

Answer 26

- coalese/arrange with hydrophobic groups burried and hydrophillic groups exposed - micelles associate with the brush border of enterocytes

Question 27

chylomicron

Answer 27

apolipoprotein B-48 - fat soluble vitamins inside here - nonphospholipid bilayer

Question 28

fatty acyl-CoA synthetase (thiokinase)

Answer 28

forms acyl-CoA

Question 29

TAG synthase

Answer 29

makes TAG via acyltransferase activity

Question 30

acyl CoA: cholesterol acyltransferase

Answer 30

-esterifies cholesterol with a FA

Question 31

secretion of lipids from enterocytes

Answer 31

enterocytes---lymph system---vascular system

Question 32

lipoprotein lipase

Answer 32

associates with the lumen of endothelial cells of capillary beds -clip out FA from TAG in chylomicron

Question 33

chylomicron digestion

Answer 33

liver takes up empty chylomictron and break down components to use for energy

Question 34

lipid malabsorption in gallbladder/liver

Answer 34

bile issues, can't stabilize droplets

Question 35

lipid malabsorption in pancrease

Answer 35

enzyme issues (can't clip lipids off of macromolecules)

Question 36

lipid malabsorption in stomach

Answer 36

can't bring stuff in

Question 37

cystic fibrosis

Answer 37

- disability for producing pancreatic enzyme released into small intestine - defect in chloride ion channel - hard time getting water into ducts - mucus clogs ducts

Question 38

number one reason for lipid malabsorption

Answer 38

pancreatic