2. Lipids
95% of dietary lipids are TGs; the rest are
phospholipids, free fatty acids (FFAs),
cholesterol (present in foods as esterified
cholesterol), and fat-soluble vitamins.
The primary function of TGs is to store
energy in adipocytes and muscle cells
cholesterol is a ubiquitous constituent of
cell membranes, steroids, bile acids, and
signaling molecules
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13. Lipoproteins
What happens to the cholesterol and other fatty
acids that we eat? How do they get into our
bloodstream?
How can fatty acids (which are hydrophobic and thus
only slightly soluble in aqueous solution) be
transported in the blood (which is an aqueous
solution/suspension)?
Some SIMPLE unesterified FAs are merely bound to
serum albumin and other serum proteins, and are
transported through the bloodstream by these
proteins.
PHOSPHOLIPIDS, TGs, CHOLESTEROL and
14.
15. Lipoproteins
LP core
Triglycerides
Cholesterol esters
LP surface
Phospholipids
Proteins
Cholesterol
Lipoproteins
function in the blood
plasma as transport
vehicles for TAGs
and cholesterol.
16. Lipoprotein Classification
1) Chylomicrons: Transport
dietary TAGs and cholesterol
from the intestines to the liver
2) VLDL: very low density
lipoprotein
3) IDL: intermediate density
lipoprotein
4) LDL: low density lipoprotein.
transport endogenous TAGs
and cholesterol from the liver to
the tissues.
5) HDL: high density lipoprotein
Transport endogenous
cholesterol from the tissues to
the liver.
17. • Dietary TGs are digested in the stomach and
duodenum into monoglycerides (MGs) and FFAs by
gastric lipase, emulsification from vigorous stomach
peristalsis, and pancreatic lipase.
• Dietary cholesterol esters are de-esterified into free
cholesterol by the same mechanisms.
• MGs, FFAs, and free cholesterol are then solubilized in
the intestine by bile acid micelles, which shuttle them to
intestinal villi for absorption.
• Once absorbed into enterocytes, they are reassembled
into TGs and packaged with cholesterol into
chylomicrons, the largest lipoproteins.
