Lipid Digestion and Absorption Flashcards Preview

Biochem BLOCK 2 > Lipid Digestion and Absorption > Flashcards

Flashcards in Lipid Digestion and Absorption Deck (38):
1

How many grams of lipids do adults consume?

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

2

Acid Lipase

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

3

lingual lipases

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

4

gastric lipase

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

5

emulsification of lipids

-small intestine

two complimentary actions:
-mechanical agitation
-bile salts secretion

6

mechanical agitation in emulsification of lipids

-dietary material via peristalsis increases the lipid droplet surface area

7

Bile salts secretion in emulsification of lipids

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

8

detergent properties of bile salts

stabilize particles as they become smaller, prevents them from coalescing

9

components of bile

glycine and colic acid

10

pancreatic enzymes

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

11

digestion

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

12

What are some pancreatic enzymes?

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

13

pancreatic enzymes responsible for TAG digestive

-pancreatic lipase
-colipase

14

pancreatic enzymes responsible for cholesterol ester digestion

-cholesterol esterase

15

pancreatic enzymes responsible for phospholipid digestions

-phospholipase A2
-lysophospholipase

16

TAG digestions

too big for intestinal mucosal cells to endocytose efficiently

17

pancreatic lipase

-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

18

colipase

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

19

cholesterol esteras

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

20

Phospholipase A2

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

21

lysophospholipase

-pancreatic enzyme
-phospholipid digestion

22

Gut endocrine cells

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

23

CCK

-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

24

secretin

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

promotes:
-bicarbonate, makes alkaline

25

micelles

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

26

Enterocytes

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

27

chylomicron

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

28

fatty acyl-CoA synthetase (thiokinase)

forms acyl-CoA

29

TAG synthase

makes TAG via acyltransferase activity

30

acyl CoA: cholesterol acyltransferase

-esterifies cholesterol with a FA

31

secretion of lipids from enterocytes

enterocytes---lymph system---vascular system

32

lipoprotein lipase

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

33

chylomicron digestion

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

34

lipid malabsorption in gallbladder/liver

bile issues, can't stabilize droplets

35

lipid malabsorption in pancrease

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

36

lipid malabsorption in stomach

can't bring stuff in

37

cystic fibrosis

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

38

number one reason for lipid malabsorption

pancreatic