00:00
So now let's take a look
at how lipids are digested
in the small intestines.
00:06
This is going to require the
process of emulsification.
00:11
In this process triglycerides
and their breakdown products
are insoluble in water.
00:17
So they must be
pretreated with bile salts
that will break down
these larger fat globules
into smaller globules
that can now come in contact
with the proper enzymes.
00:31
Once they are broken down
into more manageable globules
digestion is going
to take place.
00:37
During digestion pancreatic
lipase has are going
to break down our fats
into monoglycerides
in two fatty acids.
00:46
So we started as a triglyceride,
now we're a monoglyceride
and two free fatty acids.
00:54
Those numbers are important.
00:56
Next we have my cell formation.
01:00
This occurs from
products from digestion
become coated with bile salts
and another molecule
known as lecithin.
01:09
From their lipid products
will diffuse or leave
the micelles and cross
the epithelial membrane
by way of diffusion.
01:19
Then we have
chylomicron formation.
01:23
In this process the lipid products
are going to be converted back
into the triglyceride form
and packaged with the lecithin
and lipoproteins in the
form of a chylomicron.
01:36
These chylomicrons are then
transported or exocytosed
from the basolateral side
and then instead of
entering the blood
they enter the lymph by way
of the lymphatic lacteals.
01:51
These are then going to
eventually be emptied
into the venous blood
at the thoracic duct.
01:59
So once in the blood
the chylomicrons are broken
into free fatty acids
and glycerol by
lipoprotein lipase has
so that they can be
used by the cells.
02:10
Short-chain fatty
acids can diffuse
directly into the blood
without going through
the chylomicron process.
02:18
So to recap using a diagram.
02:21
Emulsification
involves bile salts
that are released
from the gallbladder
into the duodenum
breaking large fat globules
into smaller fat droplets
that are then going to increase
the surface area of the fat
available to lipase enzymes.
02:40
From there,
the pancreatic lipase is
are going to hydrolyze
our triglycerides
yielding monoglycerides
into free fatty acids.
02:52
Micelles consisting
of the fatty acids
and monoglycerides
as well as bile salts
are then going to
ferry their contents
to the epithelial cells.
03:04
After this, fatty acids
and monoglycerides
are going to diffuse
from the micelles
into the epithelial cells.
03:14
Then fatty acids
and monoglycerides are
recombined and packaged
with other fatty substances and
proteins to form chylomicrons.
03:24
These chylomicrons
are then extruded
from the epithelial
cells by exocytosis
and enter lacteals
and and then are carried
away from the intestines
in the lymph.
03:39
So to summarize,
some lipid digestion is
going to begin in the mouth
and the stomach but this
is mostly going to occur
in babies and less so on adults.
03:48
After this,
most of our lipid digestion
is going to actually occur
in the small intestines.
03:54
Where large fat globules
are broken down
into small droplets
by emulsification
with bile salts.
04:04
Emulsification allows
the pancreatic lipases
to access the lipids
where they are broken
down into monoglycerides
and free fatty acids,
once inside the
epithelial cells,
the monoglycerides and free
fatty acids will recombine
and are repackaged
into chylomicrons.
04:26
The chylomicrons are then
exocytosed to lacteals,
which will then be
subsequently transported
to the lymphatic vessels.