Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biochem Block 2 > Lipid digestion and absorption > Flashcards

Lipid digestion and absorption Flashcards

1
Q

US adult consumption of lipids

A
  • 81g a day
  • 90% are TAG(72g)
  • The rest is…
  • cholesterol
  • cholesterol esters
  • phospholipids
  • free fatty acids

-most digested are esterified

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Acid lipases

A
  • acid-stable lipases function in the stomach at pH 4-6
  • Inguinal lipase: secreted from glands at the back of the tongue
  • Gastric lipase: secreted from the gastric mucosa
  • target TAG containing SHORT AND MEDIUM chain fatty acids(release FA straight into the blood stream)
    - milk fat
  • important in neonates when milk is the primary food source
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Emulsification in the small intestine

A
  • two complimentary actions:
    1. mechanical agitation
    - peristalsis to increase fat droplet surface area
    2. bile salts secretion
    - made in the liver, stored in the gallbladder
    - secreted to small intestine
    - have detergent properties that STABILIZE particles as they become smaller and prevent them from COALESCING
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

pancreatic enzymes in general

A
  • want proper pH and all necessary compnenets, so very coordinated process
  • Enzymes secreted from the pancreas digest dietary TAG, cholesteryl esters and phospholipids
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Digestion of FA

A

-removal of specific fatty acids by breaking ester bonds attaching the fatty acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

TAG digestion

A

-TAG is too big for intestinal mucosal cells to endocytose efficiently

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Pancreatic lipase

A
  • an esterase, cleaves fatty acid at Carbon 1 and 3 of glycerol backbone.
  • creates 2 fatty acids and a 2-monoacylglycerol
  • represents 2-3% total protein in pancreatic secretions
  • high catalytic efficiency
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

If someone has a deficiency of pancreatic enzymes, what should you give them?

A
  • pancreatic lipase

- hella active

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the maximum number of free fatty acids produced from pancreatic lipas?

A

-one 2 per TAG because you have to keep one attached to the glycerol backbone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Colipase

A
  • TAG digestion
  • binds to pancreatic lipase at 1:1 ratio
  • anchors pancreatic lipase at the lipid-aqueous interface to promote pancreatic lipase enzymatic activity when inhibitory bole salts are present.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Cholesteryl ester digestion

A
  • dietary cholesterol is present in two forms
  • 90%-nonesterified (free)
  • 10%-esterified cholesterol (cholesteryl ester)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Cholesterol esterase

A
  • cholesteryl ester digestion
  • pancreatic enzyme secreted to the small intestine to digest esterified cholesterol
  • producing cholesterol and fatty acids
  • all cholesterol is finally non-esterified
  • bile salts promote cholesterol esterase activity
  • ONLY FOR ESTERIFIED
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Phospholipid digestion

A

-ingested phospholipids are digested by sequential removal of fatty acids by two different pancreatic enzymes, producing two fatty acids and one glycerylphosphoryl base

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Phospholipase A2

A
  • 1 enzyme used in phospholipid digestion

- removes the fatty acid from POSITION 2 to produce lysophospholipid and a free fatty acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Lysophospholipase

A
  • 1 enzyme used in phospholipid digestion

- removes fatty acid from POSITION 1 to generate one fatty acid and one glycerylphosphoryl base

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Glycerylphosphoryl bases

A
  • we need it to get coline to make bile salts
  • can be…
  • absorbed
  • further digested
  • excreted into the feces
17
Q

Coordinating Digestion of dietary lipids

A
  • sensing the presence of dietary lipids and pH (and proteins)
  • CCK
  • Secretin
18
Q

Gut endocrine cells

A
  • in the mucosa of the lower duodenum and jejunum
  • sense…
  • lipids and partially digested proteins
  • the low pH of chyme entering the intestine
  • they secrete 2 small peptide hormones into the blood
19
Q

Cholecystokinin (CCK)

A

-a small peptide hormone secreted to the blood in response to the presence of lipids and partially digested proteins
Positive:
-promote pancreatic enzyme secretion (exocrine cells to the intestine)
-cause gallbladder to secrete bile

Negative:

  • decreases gastric motility to reduce the release rate of gastric contents to the small intestine
  • gives enzymes time to be able to do their work
20
Q

Secretin

A
  • peptide hormone secreted to the blood in response to the low pH of chyme entering the intestine
  • promotes release of bicarbonate rich solution from pancreas to small intestine
  • provides the appropriate pH for optimal pancreatic enzyme function
21
Q

Lipid digestion in jejunum

A

3 primary products

  • free fatty acid
  • free cholesterol
  • 2-monoacylglycerol

mechanism for getting fat soluble vitamins into the body

22
Q

Micelles

A
  • disk-shaped clusters of amphipathic ipids

- formed from 3 products of lipid digestion in J, bile salts, and fat-soluble vitamins

23
Q

Micelle function

A
  • polar group towards aqueous solution, hydrophobic group toward the center
  • as micelle is formed, it recognizes its center and its environment
  • water doesnt mix well with chyme so water layer is perfect for micelles and the polar group comes off
  • FA tails exposed and the molecule flips into the membrane of enterocytes
  • thats how fat soluble molecules get into cells
24
Q

Chylomicrons

A
  • in ER
  • for complex lipid biosynthesis
  • Cholesteryl ester and TAG are main things put inside(neutral)
  • pocket that forms between 2 layers of ER
  • HAVE APOLIPOPROTEIN b-48 ASSOCIATED WITH IT
  • excreted into the lymph system
  • sealed chromonolipid bilayer
25
Q

Apolipoprotein B48

A
  • associated with chylomicrons

- NOT apolipoprotein 100 found in liver

26
Q

Fatty-acyl-CoA synthetase

A
  • thiokinase

- converts long chain fatty acids to their activated form by using energy from ATP–>AMP to form fatty acyl CoA

27
Q

TAG synthase

A

-2-monoacylglycerol is converted to TAG by an enzyme complex that sequentially adds activated fatty acids by two enzymatic acyltransferase activities

28
Q

Acyl CoA: cholesterol acyltransferase

A

-esterifies cholesterol with a fatty acid

29
Q

Chyle

A
  • lymph which contains chylomicrons

- passes via the lymphatic system to the thoracic duct, from thoracic duct to subclavian vein, and then enters blood

30
Q

Lipoprotein lipase

A
  • enzymatically degrades TAG in the circulating chylomicrons to free fatty acids and glycerol
  • synthesized and secreted primarily by muscle and adipose tissue(also heart, lung, kidney, liver)
  • associates with the lumen endothelial cells of capillary beds
31
Q

Lipid malabsorption

A
  • problems with gallbladder, or pancreas, or intestinal cells being able to bring materials in
  • BIGGEST PROBLEM: pancreatic enzyme issues and gallbladder issues
  • cant stabilize smaller droplets, pancreatic enzymes cant remove fatty acids
  • cant clip lipids off molecules
32
Q

Cystic fibrousis

A
  • not all about breathing(long term)
  • Short term: children have energy and need to grow, but they cant produce pancreatic enzymes to the small intestine.
  • defect chloride ion channel in duct between pancreas and intestine so water cannot get into the mucous and so the duct gets clogged.
  • cant digest FA for energy
  • cant create micelles and chiromicrons to get fat soluble vitamins into the body
  • Treatment: have sufficient energy in their diet.
  • increase pancreatic enzymes because they are hella active

Biochem Block 2 (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions