Triacylglycerols

Triacylglycerols
(as well as free fatty acids and both free and
esterified cholesterol) are
very hydrophobic
. They are not
soluble in water unless they are emulsified or included in micelles
in the presence of tensides.
In the intestine
fat droplets are emulsified in the presence of
bile salts
and form
mixed micelles
from the products of digestion catalysed by the
pancreatic lipase
.
Lipid absorption is preceded by dissociation of the micelles and
the components are separately absorbed through the brush
border microvilli of the epithelial cells (enterocytes) lining the
lumen.
The mixed micelles
in the chyme
are composed, in varying proportions, of the fatty acids (FFA),
mono- and diacylglycerols (MG and DG), perharps some unhydrolysed
triacylglycerol (TG), and anions of bile acids, together with minor components
of the diet such as phospholipids and fat-soluble vitamins.
In the extracellular fluids
hydrophobic lipids are transported in the form of
lipoprotein
particles