- [Narrator] Now that we've gone through
the small intestines and mentioned the different
enzymes and components being secreted into it,
it probably helps to figure out
where those enzymes are coming from.
A lot of the secretions that go into the GI tract
come from accessory organs.
One such accessory organ, is the pancreas.
The pancreas is gonna secrete a whole series
of digestive enzymes,
but also sodium bicarbonates.
Now this digestive enzymes can break down carbohydrates.
They can break down some lipids.
They can break down proteins.
The sodium bicarbonate is helping as a buffering.
A buffering which will help take the acidic solution,
which came from the stomach,
and help to buffer it back to more of a neutral solution.
Which is where the small intestines likes to be.
So two of these digestive enzymes are
Trypsin and Chymotrypsin.
Both, Trypsin and Chymotrypsin, are going to work
on breaking down proteins.
That means, in the stomach we had Pepsin,
in the small intestines we're gonna have
Trypsin and Chymotrypsin, which are being secreted
by the pancreas.
We also have pancreatic amylase.
While the pancreatic amylase is helping to break down
our carbohydrates.
And we have Lipase.
While Lipase, it kind of sounds like lipids,
so Lipase breaks down lipids.
So all three of these, proteins, carbohydrates and lipids,
can all be broken down by different enzymes
and all these enzymes are secreted from the pancreas.
One thing to note, each one of these, protein,
carbohydrate, lipid,
each one is broken down by a very specific enzyme.
You can't just take carbohydrates and say
Lipase breaks them down.
It doesn't wort that way.
So each enzyme is specific to what it can break down.
Another accessory organ is gonna be the liver.
The liver can produce bile.
Now, bile is not an enzyme.
Bile's called an emulsifier.
It emulsifies lipids.
So, what emulsify actually is,
is it take lipid molecules and pull them apart.
So you still have lipids
but instead of one big chunk of lipid
it's broken into many smaller pieces of lipids.
So by separating it, you've increased the surface area.
The liver also deals with the system called
the hepatic portal system.
Now, the hepatic portal system
is going to take all the blood from the digestive tract
and shuttle it into the liver.
Well, why do you think you'd want to collect all the blood
from the digestive tract?
I mean, you have the arteries that bring the blood in.
Gives the nutrients and gases to the different parts
of the GI tract.
And then you have the veins,
which are a part of a hepatic portal system.
The veins are gonna collect all that blood,
bring it all from the GI tract, back to the liver.
So, why?
Well, think about what you eat and what you ingest.
Is the food you eat liquidy drink, sterile,
totally clean?
Not a single thing in it they don't want?
Unfortunately not.
You're gonna have bacteria,
you're gonna have little particles, you're gonna debris.
Well, all these things,
that are being ingested,
they're being sometimes absorbed through the walls
of the intestines.
That means they're entering your blood stream.
What can happen is, the hepatic portal system
can help filter and clean out
those particles and things that shouldn't be there.
But, on a better note, the hepatic portal system
also helps to sort nutrients and store some nutrients.
Look just usually below the liver,
make it look toward the front, you'll find the gallbladder.
The gallbladder is going to take the bile from the liver,
it's going to concentrate it and store it.
So the liver produces bile,
which then goes down to the gallbladder,
the gallbladder concentrates it, pulls the water out,
and then stores the bile until necessary.
That necessary is when the body needs to break down lipids.
So if you've ingested lipids,
your body will cheer the gallbladder to release.
But if you're thinking, well,
what happens to the person
that had to go through gallbladder surgery?
Had their gallbladder removed.
Well in that case, the liver still produces bile.
The difference is though, the bile goes straight
into the small intestines.
There's no storage and concentration.
So the individuals that are without a gallbladder
a lot of times have to kind of keep an eye their diets.
Watch how much lipid they're ingesting.
Because their body can only handle so much at a time.
Because there's only so much bile available at a time.
In this diagram you can see the liver,
that huge thing taking up almost
a good third of the screen there if not more.
Then just below the liver, come off to your left,
you can see the gallbladder in green.
The gallbladder is connected into the liver.
But both the liver and gallbladder then,
are connected down through the pancreas,
that yellow thing, the pancreas,
into the small intestines.
Specifically, the duodenum or duodenum.
Again, pronunciation either or.
So all this different pancreatic juice,
all these different enzymes,
all these different chemical substances,
are coming in to the duodenum.
Well, once you finally get through that small intestines,
you end up in the large intestines.
Now, the large intestines can also
absorb nutrients and water.
But not nearly as much as the small intestines.
The small intestines really is
where the majority of it occurs.
So what's the large intestines doing?
Well, it's temporarily storing waste.
It'll escort waste if your body is ready for elimination.
And then it'll eliminate all the solid waste at one point.
So we're looking at this large intestines here.
You can see the small intestines
is leading into the large intestines.
It past the valve called the Ileocecal valve.
Well, this valve has a main purpose of back flow prevention.
Because, what's inside of the large intestines?
What's in the large intestines is all the waste.
And you really don't want that waste
going back up into your system.
Well here's that appendix again,
really no digestive function,
but it's all sitting down there so.
The cecum.
The cecum is the start of a large intestines.
It's where all the broken down particles
and waste product, leaves the small intestines
and enters the large intestine.
The area's called the cecum.
You head up the ascending,
across the transverse colon,
down the descending colon
into the sigmoid colon.
Eventually, you're storing in the rectum.
Once enough has been stored in the rectum
and potentially pushing up into the sigmoid colon there.
Once enough is stored, the body is going to release it.
So it's going to release it through defecation.
Right through the anal canal.
Now, on the anal canal, which ends at the anus,
you can see there's an internal and external
sphincter muscles.
So you have two different and very distinct
sets of muscles around the anus.
These muscles are meant to control
either the defecation process,
allowing the defecation to occur.
Or, control the defecation process
by not allowing defecation to occur.
So the internal, smooth muscle,
your body controls it.
It says what it wants to
and when it doesn't want to open up.
You have absolutely no choice over it.
The external anal sphincter, which is skeletal muscle,
that's the one you have conscious control over.
So that's the muscles that needs to either be
closed or opened by a conscious action of your thoughts.