[Music]
YUM steak as soon as it enters my mouth
digestion begins I chew to break it down
into manageable chunks my tongue mixes
saliva into the beefy mix and off it
goes through my digestive system you
should already know about the digestive
system if not you may want to watch this
video first we've previously discovered
that different enzymes break down
different food molecules which is quite
important because we saw that digesting
lipids was a little more complicated and
required bile and emulsification to help
along the way which is what we're going
to look at in more detail in this video
before we start let's think about why we
choose to break up our food and why our
stomach muscles churn up the
semidigested mix it increases the
surface area for the enzymes to work on
thus speeding up the rate at which our
body can break down the food to extract
the energy from it that we require now
let's fast-forward to our stomach our
chewed up stomach churned food has a
large surface area and is mixed with the
stomach's gastric juices these are
watery and these together with the
watery saliva secretions of the oral
cavity mean that the food is now in
quite a watery solution this is called
quorum if you've ever added water to a
greasy pan after cooking you'll know
that water and fats and oils or lipids
don't mix too well you end up with oily
droplets pretty much the same thing
happens in our stomach our watery
mixture of quorum contains big globules
of fats and oils which won't be mixed
into the solution this is a problem
because it means that the lipids have a
small surface area for the lipid
digesting lipase enzymes to work on the
lipase enzymes are added in the small
intestine at the same time a special
substance called bile is also added to
the corium the bile increases the
surface area of the big fat globules by
breaking them up into smaller fat
droplets the increased surface area of
the lipid
oklets increases the rate of digestion
of lipids by the lipase enzymes because
more lipid is available for digestion at
any given time lipase enzymes can now
more quickly break the lipids up into
fatty acids and glycerol thanks to the
bile addition the process of increase in
the surface area of the lipids is called
emulsification the bile is produced in
the liver and stored in the gallbladder
it's released down the bile duct into
the small intestine from the gallbladder
not only does the bile increase the
surface area of the lipids it also has
another great quality its alkaline this
helps to neutralize the strong
hydrochloric acid which is added to the
quorum and provides a more optimum pH
for enzymes in the small intestine to
work in to end with a random fact the
bile is green in color and it's this
that makes your poop brown in this video
we've learned that bile is produced in
the liver and stored in the gallbladder
from here it's released down the bile
duct into the small intestine where it
divides big globules of lipids into
smaller droplets this increases the
surface area of lipids available for the
lipid digesting lipase enzymes to work
on if you liked the video give it a
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comment below if you have any questions
why not check out our first graph as
well until next time