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Chapter 22 Lecture | Richard Matthews | YouTubeToText
YouTube Transcript: Chapter 22 Lecture
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Summary
Core Theme
The digestive system is a complex series of organs responsible for breaking down food into absorbable nutrients, facilitating bodily functions, and eliminating waste. This process involves mechanical and chemical digestion, absorption of nutrients, water, and electrolytes, and is aided by accessory organs like the liver and pancreas.
chapter 22
digestive system we're going to take a
look now at
a really interesting system we're going
to overview our digestive system we're
going to talk about the oral cavity
pharynx and esophagus
we're going to talk about the stomach
large and small intestines the accessory
organs of digestion and then
how we actually do breakdown and digest
so this chapter is about the digestive system
system
which is defined as a set of organs that
breaks down food items in the nutrients
that can be delivered by the bloodstream
to cells in the body
now this is located a lot a big part of
your body is
located from the very front of your oral
cavity all the way down to your anus
so what we say is this food
is going to run along what we call a elementary
elementary
canal also known as your gi tract
gastrointestinal tract
and with help of your accessory organs
so your digestive system has got
two parts to it organs that the food
actually goes through
which is your elementary canal and
organs that are accessory digestive
organs such as things like the liver
now the elementary canal and i
definitely want you to know the parts of this
this
for your test this is a continuous tube
through which
food passes directly so talk about the
oral cavity
pharynx esophagus stomach small large intestines
intestines
this is where the food's actually going
to touch accessory organs
that actually are not part of the
elementary canal but do assist in digestion
digestion
are the teeth the tongue which do touch
the food
celery glands the liver which is not
touch the food gallbladder and pancreas
which do not touch the food they don't
even come in contact with that
um usually the the
accessory organs don't touch the food
but the teeth and tongue you know they
do but they're not actually a
canal where the food actually is going
to pass through like the rest of your
elementary canal is so
interestingly enough about the system
something that's pretty cool one to
point out
this is actually a tube that runs from
the oral cavity you can see on the top there
there
all the way out to the back of the anus
so at any given point
something is passing through there so really
really
it's actually outside of your body which
sounds funny because i say no it's not
something inside
it's actually not though because the tube
tube
runs completely through with no breaks
in it
so it's actually a tube that goes all
the way through so you can swallow something
something
and it's going to come out so it's kind
of interesting
now the fundamental function of the
digestive system
is to take food into the body and break
it down so we can use it
so you have to be able to break really
big molecules
into really small molecules and we do
that by digesting them
another function that your your
digestive system
is going to have is to play a role in
fluid balance electrolyte balance
acid-base homeostasis
taking in water electrolytes and deliver
them to the blood
we also ingest vitamins and minerals
produce hormones
excrete metabolic waste all those are
really important functions of our digestive
digestive
system now digestion
can occur by a couple of basic processes
one of these is called
ingestion ingestion is where food and
water are brought into the digestive
system by ingestion
so this is how you you take it in your body
body
you put in your mouth so in order normal
conditions that's where you're going to
do it
secretion this is where digestive organs
contain both endocrine exercises secrete
a lot of substances so secretion of
substances is going to help you digest
their food mucus enzymes acid hormones
all those things will be secreted
and they will help aid in the digestive process
process
the next type of process we have is
called propulsion
propulsion is where ingestive foods and
liquids are passed from one part to the next
next
this is usually accomplished by smooth muscle
muscle
and what's happening here is that
peristalsis is occurring
peristalsis is these smooth rhythmic contractions
contractions
of the smooth muscle and what that does
is to push
food through your digestive tract the
thing about it
is that it is actually um
very slow it takes a long time for this
to happen
and it may take hours for one
contraction to occur
and then the actual process of digestion
mechanical digestion and chemical
digestion actually breaks down
the large components into smaller ones
now after the food particles are broken
down into smaller particles they
actually move
through the wall of the elementary canal
into blood vessels or lymphatic vessels
what we call this is absorption this is
where water electrolytes vitamins are
also absorbed in the blood
so small really really small things are
taken into
the blood or lymph vessels
anything that's not digestible is taken out
out
so we we say that it's actually
transmitted by
feces through defecation that's uh what
we know as elimination and
you know um number two basically
the defecation provides the body with a
way to eliminate
metabolic waste uh it's actually
propulsion that's how
it is it's just a specialized form of propulsion
motility or the movement of the
elementary canal is a process
that happens in every region of it so in
the oral cavity and the pharynx that's the
the
top part of the esophagus and last part
of your small intestine
motility is due to skeletal muscle
that's what you can control
so that's you chewing and swallowing and
that's you
controlling when you go to the bathroom
for the rest of the elementary canal
it's the smooth muscle that's working
now the motility is regulated by the
autonomic nervous system
or the enteric nervous system the
autonomic nervous system is a branch of your
your
nervous system that's going to be
automatic in functions so this is going
to automatically cause you to digest
your food without you having to think
about it
the enteric nervous system is a
self-contained branch of the autonomic
nervous system that's actually extending
from the esophagus to the anus
so you actually have some some
neurons in here that are part of your
enteric nervous system
that are going to be helping your
nervous system tell your smooth muscle
now you also have some protection inside
here the peritoneal membrane
the peritoneal membranes in your
abdominal cavity are called a peritoneum
the parietal peritoneum is the outside
wall that lines the inner surface of the
body wall
the visceral peritoneum that's going to
line the actual organs visceral means organs
organs
so this is going to hold those things in
place so they don't fall apart
between these two peritoneal layers we
find the peritoneal cavity
this has got fluid this has got fluid in
it to help make sure
that your your
so the organs are located entirely
within the peritoneal cavity
we call them intraperitoneal which means
they're inside that cavity
other abdominal organs we say are
retroperitoneal retro means behind
so partially or completely located
outside the peritoneal cavity
the visceral peritoneum folds over on
itself around certain organs
and we we call this end up call this mesentery
mesentery
mesentery is actually with a majority of
what you would see if you were to open up
up
a a person mesentery is
very very prevalent in a person's
abdominal cavity
it houses blood vessels nerves lymphatic vessels
vessels
a lot of it's attached to the large
intestine we call it the mesocolon as in
mesentery colon
there are actually two mesenteries that
are very prominent
greater momentum it's got four layers of
visceral peritoneum
extends from the base the stomach down
to the pelvis the lesser momentum
this is a smaller mesentery that extends
from the medial surface to stomach to
the liver
so digestion actually begins in the oral cavity
cavity
when you start chewing on your food so
digestion is going to occur there secretion
secretion
about chemical mechanical digestion
propulsion you're definitely going to
know what's actually occurring here
ingestions occurring secretions
occurring mechanical chemical digestion
and propulsion but not absorption
you do not absorb any kind of food
through your mouth
the oral cavity is technically part of
the elementary canal
it houses the two accessory organs teeth
and tongue
uh in addition three pairs of sixth
grade organs the
salivary glands are located around the
oral cavity
uh what we have this is something i do
want you to know also
is that when you are munching around in
your mouth you actually turn this food
into what we call a
bolus b-o-l-u-s that's the name of
that food that's the massive food that
you deliver to your
stomach so the process of swallowing
which i also want you to know
the process of swallowing is known as
the glutitian
that's the actual name of it deglutition
is swallowing
and the bolus is the mass of food that
now the teeth and tongue
are grinding or masticating the food
they're chewing it in smaller pieces so
what the mastication does so the
munching on
increases the overall surface area of
the food giving
digestive enzymes more places to
catalyze reactions
so basically you increase the surface
area of food to be able to
eat chew more of it but tongue is also
involved in this that moves it around
helps to
chew the food into a bolus tongue also
pushes against the hard palate
and it's going to assist mechanical
digestion it's going to push your food
back towards the back your throat so you
salivary glands you got three pairs of
salivary glands just to create saliva
saliva's got a lot of stuff in it
saliva's got water enzymes mucous other solutes
solutes
through a duct in the oral cavity the
two main types of acid in our cells in
cerebral glands
you've got serous cells to secrete water
basically water fluid
enzymes generally release just before
or during eating so that's when you
salivate whenever you are hungry
mucous cells secrete mucus this is
keeping your oral cavity moist
so these things are releasing mucus all
the time
because uh your oral cavity should be
fairly moist all the time
they are actually a little bit less
active at night
so that explains when you're sleeping
you get dry mouth when you wake up
you're thirsty on something to drink
because they don't secrete as much
as you're sleeping that's that's one of
the uh problems with morning breath
saliva is mostly water you also got some
electrolytes like sodium chloride potassium
potassium
got some mucus you've also got some very
important things
such as salivary amylase
salivary amylase is an enzyme and what
that does
is to help break down carbohydrates
this is the reason why you start to you
eat bread
it starts to taste sweet you also have
something called
lysozymes these are bacterial killing
enzymes so i want you to
answer as your first discussion question
why do you think you need to have
bacteria killing substances
in your mouth so i want you to tell me
what you
why do you think you've got lysozyme in
your saliva like what's the purpose of
that why would you need to kill bacteria there
there
so let me know as your as your first
discussion question why you think you've got
got
lysozymes in your mouth
you've also got secretory iga iga is a
type of immunoglobulin that binds to
pathogens and mediates their destruction
you've also got bicarbonates this is the
function of the system neutralize any
acid from the stomach that regurgitates
on the esophagus
does that ever happen yes that happens
quite often actually
so that bicarbonate is there to help
you not get burned from any kind of
stomach acid that's actually going to be
coming back up
now saliva performs several functions in
the oral cavity
moistening lubricating cleansing the
oral mucosa
lysozyme and iga deterring growth of
bacteria mechanical digestion
is also achieved by this it can help
moisten and swallow that bolus
that's the reason you have it in the
first place chemical digestion
again by salivary amylase this is why your
your
your breast starts to taste sweet the
more you eat on it because it gets
broken down into smaller molecules
and dissolving dissolving food molecules
the pharynx or the throat only the
oropharyngeal laryngeal ferrous are part
of the elementary canal the nasopharynx
is not a place where you should have any
kind of food or water
that's why it burns when when milk comes
out your nose or
water comes and gets in your nose that
should not be there that's not what
that's for
you've also got some tonsils located in
the in the orthopharynx the palatine and
lingual tonsils
what these do is to help deter bacteria
that may get into your cavities
the reason for that is because you want
uh to be able to have some kind of
defense against things that are going to
enter that cavity
because you are looking towards the outside
outside
which may have all kind of stuff now the
primary function of the of the pharynx i
do want you to notice what the primary
function is i did ask you about this
is propulsion that's what it does in the
form of swallowing
which is where the bolus passes through
the pharynx in the esophagus so
the pharynx is there to push the food
the esophagus the esophagus is a tube
it's about 10 inches long found behind
the trachea and it forms
transports the bolus from the pharynx to
the stomach it's got stratified squamous
non-keratinized epithelium so it's not
very hard
but what it does it's very tough to
where if you actually push something
down it
it really shouldn't rip it i want you to
think about all the kind of things that
we eat in a day
eat some potato chips might be hard you
know that sort of thing
um you have to have a strong kind of
uh epithelial tissue there to prevent
that from from damaging you
at the junction of the ferrous in the
esophagus the muscularis externa
is a modified sphincter we call this the
upper esophageal sphincter this controls
the passage of the bolus of the esophagus
esophagus
the gastroesophageal sphincter also
known as the lower esophageal sphincter
regulates the passage into the bolus of
the stomach now
why who cares well we care about these because
because
they're closed normally they open to let in
in
the bolus and the esophagus the upper
esophageal sphincter
the gastroesophageal sphincter opens up
to let the
food into the stomach it prevents
stomach acid from re-entering the
esophagus it should prevent it
now think about what happens whenever
you lay down after you've eaten
they tell you not to eat a couple hours
before you go to bed for two reasons one
you gain weight if you're doing that
metabolizing you know and it's going to
help you gain weight
also if you lay down then
that stomach acid content might be
pushing along the back of that
lower esophageal sphincter and that's
when we stomach acid in there which we
get acid reflux
so the best time to eat is before
bedtime way before bedtime
and not after or after you should be sleeping
sleeping
now the primary functions of the
esophagus are propulsion and some secretion
secretion
what the esophagus does is to undergo
peristalsis where you push the bolus
towards the bottom even if you stand on
your head you're still going to have it
pushed down that's what
what that does now again because the esophageal
esophageal
epithelium is so thick it prevents any absorption
absorption
so that's not going to be the place
where you absorb your food it's just
going to ride that tube down
so that it can be put into your stomach
now swallowing also known as
de-glutation is a specialized type of
propulsion which we push
food down our oral cavity to the stomach
you've actually got several muscles that
are involved in this relies on
coordinating action of the upper
elementary canal
saw pilot pharynx esophagus uh
the tongue actually is is important to
this and it actually plays
a role that's the only one that's
actually playing a role directly in motility
motility
you have three phases of swallowing
the voluntary phase that's you pushing
the food towards the back of your throat
the pharyngeal phase where you enter it
and that sits off the esophageal phase
where it's moved down to your stomach
that you actually don't
control in the lab portion of the course
we're going to we're going to talk about
the stomach
we're going to look at the stomach in
the lab portion and the stomach
is pierced by the esophagus at this what
they call the esophageal hiatus
and this is emptied into that j shaped
organ known as the stomach
the stomach has got lesser and greater
curvatures that forms wrinkles called
rugae when empty
the rugay are wrinkling it up when it's
empty because it can stretch
now you probably can probably understand
why this would stretch
because you have to be able to make it
bigger where you can receive food
you've got five regions of a stomach
you've got the region of the
esophagus esophagus empties in the
stomach that's the cardia
it's called cardia because it's right
next to the heart the fundus is the dome portion
portion
superior to the esophageal opening the
body is the main portion
a pyloric region is the narrow inferior
end the antrim pyloric canal is where
you have this
and the last part of the stomach is
called the pylorus which is going to actually
actually
hit the intestine the pyloric sphincter
which is at the end of the stomach is
going to control the flow of ingestive food
food
between the stomach and the small
intestine so you don't just push all of
your food out of the stomach at one time
it's actually controlled
a little bit at a time that way it
the stomach has the same four tissues as
the rest of the elementary canal
uh with exceptions that you still
actually have an additional oblique
layer smooth muscle
that performs something called churning
we haven't talked about turning yet
churning is kind of moving it around
really quickly and
mixing around fast this is going to
pummel the food into liquid called
kine i definitely want you know about
kind you'll see it again
chyme is what's going to be left over
from stomach secretions and food
and you're that's going to go to your
small intestine chyme is released
uh very very little bit at a time in in
your intestine
to your testosterone from your stomach
the mucosa of the stomach is heavily indented
indented
to form what we call gastric pits these
have got
cells in their columnar numerous goblet
cells what that does
is to protect the stomach now think
about it for a second you know the
stomach is going to digest a lot of stuff
stuff
how come the stomach doesn't digest
itself that's because you've got these things
things
you've got the mucus that's going to
line the pits and protect the stomach
from its own secretions
you also got gastric glands gastric
glands are found at the base of the gastric
gastric
pits and there are multiple branched
glands that contain endocrine and
hormones cells are going to secrete uh
acid acidic enzyme containing fluid so
that's going to
help digest things that are inside of
the stomach
this is kind of what it looks like these
are the layers of your stomach wall
you got again the layers that you have
in any type of elementary canal you got
the mucosa
submucosa externa and serosa
you'll see all of these layers
throughout all of your elementary canal
these four layers you definitely will
see all of them the stomach has
there are four main types of cells in
the gastric glands
which actually each one of them secretes
a different product i definitely want
you to know
what each cell secretes so you will see
that again
i promise i definitely want you to know
the names of the cells and what each
product secretes
so at the bottom are the enteroendocrine cells
cells
these secrete gastrin which is going to
stimulate acid secretion
cheap cells secrete something called pepsinogen
pepsinogen
and when it encounters an acidic ph it
becomes pepsin
the point of pepsinogen which is what
chief cell secrete
is to help break down stem stomach
proteins so
proteins get in your stomach from
whatever you ate this pepsinogen is
going to help break it down
parietal cells these secrete
hydrochloric acid
and they're responsible for the acidity
of gastric juice
so definitely what parietal cells do
it's very important
that you have acid in your stomach it
can activate sepsis
in which would destroy a lot of
disease-causing organisms basically what
happens when you swallow any kind of bacteria
bacteria
then the bacteria will be broken down by
the acid in your stomach
and that's going to cause them to die so
they won't make you sick
you also have to have something called
intrinsic factor which is what you have
to have to be able to absorb b12
vitamin b12 so if you don't have a
stomach you can't make intrinsic factor
for b12 so
that's really it though you could
actually live without a stomach if you
had other ways to digest your food
but you cannot live without this b12 so
you have to uh
if you don't have a stomach you gotta
take b12 shots
now the cells located towards the top of them
them
are called mucous neck cells they're
called that because they line the neck
of the gland
so mucous neck cells again prevents
neutralization of acid produced by the
parietal cells
so basically what's happening here is
that you don't want the
the stomach to not be acidic you want it
to be acidic and in order to do that you
have to have these
mucous neck cells that stop stomach acid
now what the stomach does for you
secretion propulsion digestion
the acid secretion uh secretes a lot of
different things including the
hydrochloric acid released by parietal cells
cells
the acid secretion occurs throughout the
day between meals what we call a basal rate
rate
and during eating the secretion
can be divided into three phases we're
going to talk about the
the cephalic phase the gastric phase
and the intestinal phase we're going to
in the cephalic phase you this is when
you think about food or you smell
food taste food start you start to salivate
salivate
so you start to
release these hormones from the stomach
to be able to release acid to be ready
for food so when you're hungry
you start thinking about food striking
oh stomach acid you start feeling it
so it's going to prepare food to be eaten
the gastric phase is what happens when
you actually do get food in your stomach
so the first two stimuli are going to
trigger acid secretion during the
gastric phase
the food is going to distinct stomach wall
wall
that's going to stretch it where it's
going to uh stimulate the
reflexes the second stimulus is when you
get parsley digestive proteins
that's going to create more gastrin
which in turn stimulates more acid
secretion to help you start breaking
stuff down
now why do you think
that you are not doing this just all the
time why is it only during
uh food in your stomach well it's
because what would happen if you were
trying to digest food that's not there
is that you would potentially burn a
hole in your own stomach lining
so this is not going to be active unless
food's in there
which is a kind of a fail-safe mechanism
to rent you from digesting your own
stomach which is really good
during the intestinal phase the final
phase of gastric acid secretion is
responsible for about 10 remaining acid secretion
secretion
which is not much this is triggered by
the partially digested proteins in the
fluid entering the duodenum
that's going to trigger the entire inner
can cells release intestinal gastrin
this is going to have the same effect as
the gastrointestinal stomach
it's going to secrete ion secretion so
this is going to be the time whenever
we trigger the presence of prosthesis proteins
proteins
and that's going to stimulate the
intestinal phase
so this is going to help you realize
that i mean you're you're getting fuller
basically you're going to be
now the stimulatory effect intestinal
phase is brief as chyme enters the
duodenum the declining ph and the
presence of lupus triggered
enterogastric reflex
which is going to decrease vagal vagal
activity and acid secretion
the low ph in duodenum which is triggers
secretion of hormones
secretin and gastrin the point of these things
things
is to really reduce acid secretion you
do not want your duodenum to be
full of acid it is not the place where
you should have a lot of stomach acid
you should have
now the stomach it's it's able to
receive food from the esophagus turn
into bolus
and control the rate at which time
empties so the stomach
in a resting state has got about a
volume of 50 milliliters or
0.2 cup but it can expand about 1500
milliliters when it's filled with
food and liquid so when food of liquid
is swallowed
the gastroesophageal sphincter and
smooth muscle the fundus and a body of
stomach relax
to allow something to fill this is what
we call receptor relaxation so
basically what happens here is that you
start putting food inside your mouth
goes down your esophagus to your stomach
and as it's pushing down there it's
gonna let your stomach to get bigger
it's true your stomach actually gets
bigger that's why you can go to the restaurant
restaurant
and after you get done your stomach's
bigger it is technically it really is so
that's actually
something that we uh
the churning function after a meal the
smooth layers of muscle
produce waves of peristalsis
there's a specialized group of cells
called a gastric pacemaker that allow
that to keep happening
and what that does is to propel the
bolus to the pylorus
where the small amounts are chyme are
propelled through by lowering sphincter
so what happens is that that the kind
that's in your stomach is pushed through
the plastic sphincter
about three milliliters at a time the
remainder of the chyme
is pushed backward in the stomach where
peristalsis weighs trying to mix it
again and then it repeats
now you felt this you feel this
when you go do this again and the
remainder economy is pushed back into
stomach and there's actually nothing there
there
that's the oh that's that when you're
whenever you are
your stomach's growling that's what's
happening the the back where it's pushing
pushing
excuse me that backwards pushing is
what's happening whenever you're trying to
to
keep emptying but there's nothing there
too empty so that's that growling
that you feel we keep these
constant about three times per minute
when you're hungry you feel
that emptiness in your stomach that's
now the emptying function the final
function of the gastric utility
we're going to push chyme through the
duodenum again about three milliliters
per time
uh liquids move rapidly from the stomach
toward them with no delay
solids must be converted so that
explains why y'all you can drink some
water and just a few minutes later you
gotta pee
it has gone into your stomach to your
duodenum into your
is got into your blood and then into
your kidneys
in that short amount of time all that's
happened in a short amount of time so
it happens very fast uh the key factor
determines the rate of that
is how much composition the amount of
time you have in the duodenum
so really what you should be doing
is eating every couple hours that way
it's never really empty it's always working
working
that'll get your metabolism going you're
speeding it up if you if you
if you wait and eat food like once a day
don't ever do that
that's bad for you if you wait to eat then
then
your body is like ah finally it's going
now the control of gastric emptying is
critical because duodenum has got a mix
incoming time
thoroughly before it moves to the rest
of the intestine the reason for that
is because it's very acidic the first
part is and you got to mix it
bicarbonate to avoid damaging the
intestinal mucosa
does that ever happen of course it does
we get intestinal ulcers all the time so
you gotta be careful with that
and chyme is generally very concentrated
so it must be diluted with water from
pancreatic juice that's another reason
why you can't be dehydrated
you really need to be drinking a lot of
water every day because all these juices
that are in your stomach and intestine
and pancreas you have to have them at
good working function
and that's how you're able to to do that
so without
water you would die and that's why you
need to drink more of it
the duodenum has to receive very small
amounts of chyme at a time against about
three milliliters at a time
now the small intestine small intestine
is about six meters long by 20 feet
that's the longest part
it's called small intestine not because
it's the
the widest uh it's actually
the smallest as far as diameter the
large intestine is
larger as first diameter has length the
small intestine actually is longer
it has four major main processes that
occur here secretion digestion
absorption propulsion
and you got cells intestinal cells also
called enterocytes
that are going to do the jobs here
enzymes also they're released by the
pancreas responsible for the bulk of
chemical digestion
and after this is occurring this is the
last place that you have
the human enzymes can actually digest
your food
so this is your that's your last chance
so your strong intestine is long
it's wavy to be able to give you more
bang for your buck
now although the nutrients are digested chemically
chemically
after that they're absorbed into the
enterocytes and the blood of lymph
sounds really quickly and your small
intestine also mixes and propels as it
goes along the large intestine
so that's one of the things that it does
is to push food along to the large
intestine so that you can
get more bang for your buck now the
small intestine has three divisions
and uh depending on who you ask there
are actually different pronunciations to them
them
duodenum is how you're supposed to say
this word
uh the initial segment begins at the
pylorus this is the shortest of the
three divisions
about 25 centimeters in length
the jejunum the next one
this is beginning to do a
duodenodrogenal flexure
it says within the peritoneal cavity
it's about seven and a half feet long
this is the place where you have most of
your chemical digestion occurring
the ilium which is the segment's final
final uh segment's about
10 feet it's the longest one terminates
at the portion
called the cecum the cecum is the last
part of the small intestine first for a
large intestine the ileocecal valve
is the is the place between the ilium
and the cecum this controls movement of materials
materials
back from the ilium into the cecum this
also prevents materials from large
intestine from going into the ilium
very important for preventing bacteria
to access your
system you have bacteria in your large
intestine you do not want them in your
small intestine because they could
poison you
so that's why you have this valve here
to control that movement
from the small intestines to the large intestine
the internal surfaces of the small
intestine contains three progressively
smaller types of folds
and what they do is to increase the
surface area what you're trying to do
when you have your small intestine is to
try to increase
your surface area to get more bang for
your buck
so we call this circular full sometimes
you may see it written as
uh plikie i c k e p-l-p-l-i-c-k-e may
see that written
plucky circular so that's in your
textbook if you get your textbook
that is what they're called the folds
actually slow down
kind and gives the nutrients time to be
digested so instead of just
rushing it all through there what it
does is to stop
stop it enough to where that the uh
the intestinal cells can take more time
to withdraw the nutrients that when you
can get
the bang for your buck that's why it
takes so long to digest anything you know
know
if you go to the bathroom and you see
that what you had in there was
uh probably from a day or so before that
because it takes a long time which is good
good
you're trying to get time to get stuff
out of there
now you actually have some folds that are
are
not visible to the naked eye they're called
called
villi the villi are projections
of the mucosa and each villus surrounds
a layer of
intestinal cells that surround blood
capillaries and something called a lacteal
lacteal
a lacteal is a lymphatic vessel what it
does is to help
capture fat from your diet anytime you
eat any kind of animal fat
you have to digest it and it doesn't
digest the same way as some of the rest
of the things in your body
so what you have to do is to digest that
fat through the lacteal
so the lacteal is a specialized
lymphatic vessel
that's going to help you digest fat now
at the very bottom of the villi we have
an indentation
called intestinal crypts these house
glands with enteroendocrine cells
that secrete mucus secreting goblet
cells what that does for you again is to
help make sure
that your intestinal lining is not
distorted by any kind of
below the villi we also have something
called microvilli
microvilli are found in the plasma
membrane of enterocytes
and these are what we call a brush
border it's called that because it looks
like a bristle brush so each enterocyte
as many as 3000 microvilli
which is a lot of them and what that
does is again to increase more surface area
area
so digestive enzymes produced and
secreted by enterocytes catalyzed reactions
reactions
that break down sugars and proteins
disaccharides and
peptides now the small intestine
motility differs during fasting and
during eating
when you're fasting very slow rhythmic contractions
contractions
along the length in a pattern called a
migrating motor complex
what this is doing for you when you're
not eating is to clear any kind of
material that's left over
and requires about two hours of pushing
digestive food from the duodenum
to the illusive valve now this is
controlled by a hormone called
modalin it means movement this is
produced by the duodenal mucosal cell so
what this is doing
is to help make sure that anything
now small intestine goes under two types
of movement during eating
peristalsis and segmentation again
peristalsis is a rhythmic alternating contractions
contractions
of the longitudinal circular muscles of
the layers of the muscularis externa
what this does is to propel chyme
towards the ilium
and ultimately through the lucical valve
so the
longitudinal muscle and circular muscles
are going to contract
by alternating they're alternating the
contractions going to push the food through
through
to be able to get down to the
end of the intestine this is how food
segmentation also known as churning is
going to
only involve the circular layer of
smooth muscle and this is going to squeeze
squeeze
basically what it does is squeeze and
and mix
these things over and over until they
are mixed together so this is going to contract
contract
now large intestine this is going to be
also called the large bowel
this runs along the border of the
abdominal cavity surrounds the small intestine
intestine
it's only about five feet long so it's
not very it's not very long
it's actually named large because it has
a larger diameter
what this does is receive material from
your small intestine that was not digested
digested
or absorbed and it's a passageway for
feces or fecal matter
so why do you have this well you have to
be able to get rid of that because you
don't want to stay in you if you didn't
digest it
it is also active in absorbing water electrolytes
electrolytes
which is critical for maintaining fluid
electrolyte and acid-base homeostasis
what the large intestine does is to
secrete which is mucus propel and defecate
defecate
it also is very important in
bacteria it houses a bunch of bacteria
that perform very important functions
such as
synthesizing vitamins so without your small
small
large intestine you would not be able to
synthesize vitamins like you
that's what it looks like look at this
in the lab portion this will be on your
lab quiz actually
of the of this digestive chapter uh
you're looking at the ascending
descending colon
the rectum sigmoid colon i definitely
want to know i definitely want you to
know the ascending transverse descending
and sigmoid colon i did ask you about
that the four colons
that's the parts in bold here on this
diagram i'm going to ask you about that
the large intestines got the following
histological features
the mucosa lacks villi and cells like microvilli
microvilli
now these are going to
uh reflect the fact that we don't absorb here
here
this is the reason why you don't have
those things you don't have microvilli
don't have villi
because you're not trying to absorb here
that's not the function
the mucosa is rich with goblet cells
that secrete protective mucus
so whatever you ate is coming out of
there it's not going to
be terribly acidic because you're going
now you have a lot of bacteria
a lot a lot is an understatement you
have about 10 times more bacteria in
your large intestine than you have cells
in your body
so there are a gazillion of them they
actually make up about sixty percent of
the dry massive feces so
most of the feces is bacteria the normal
flora gut flora
actually consists of 500 different
bacterial species
and what they do for you they get a home
and they get food and you get the
ability to break down vitamins and use them
them
for nutrition so you have to have those
and they're very important now what
happens is they break down
sulfur compounds uh some of the proteins
that you have
the nitrogen containing things they eat
them so they they
they are going to exhibit some of that
that's the
smell with gas and with flatulence and
with with feces it smells bad
that's them it's actually not you um
that's the bacteria you know that are
they produce vitamins such as vitamin k
which is very important for blood clotting
clotting
they metabolize undigested materials so
they help
digest carbohydrates that you can use
and they also did help deter the growth of
of
bad bacteria so they compete for nutrients
nutrients
and they kill the massacring chemicals
they also stimulate your immune system
this is how you get immune tolerance
uh they stimulate development of mucosal
sociology tissue
so the bacteria that you have in your
intestine are really really really important
important
because what they do is to help you stay healthy
healthy
a lot of times you can take a medication
called a probiotic
in which case you will have
um bacteria introduced into your
into your intestine now some
problems with the small and large intestines
intestines
ulcer stomach ulcers are definitely
going to be a problem you also may have
diverticulitis which is the inflammation
of the diarticula
or some of the bulges in your intestinal
wall colon cancer
is a potential problem of the disease of
the large intestine
intestinal polyps is another one so
definitely want to be familiar with some
of the problems that are associated with
now the motility of the large intestine
yeah the proximal large intestine and
this the large intestine
the proximal large intestine is
basically going to get water electrolyte balance
balance
the distal large intestine is going to
be the the place where you have the
uh fecal matter basically it's going to
be expelled
during defecation so it's actually
pretty far up there honestly it's not
really going to come out until you start
the two types of motility a proximal segment
segment
you got segmentation again the hostrum
is gonna
it's gonna contract and swirl it around
this is gonna aid in digestion
and controlled by the local neurons
triggered by a stretch this also
explains why
eat towards the bottom of the page here
whenever you eat you have the urge to poop
poop
because you're making room so we call
that a mass
movement or a mass peristalsis multiple
hostile undergo fairy sauces and they
propel that towards the large intestine
happens about three to four times a day
and it can trigger about food consumption
consumption
so when you start eating you're like oh
i gotta go to the bathroom you know
after lunch you come home you got poo
that's the reason why because you have to
to
uh it's initiated by that
the just the large intestine is actually
much less modal approximately large
intestine so
it doesn't really move a whole lot when
mass movements force fecal matter in
there then initiates a parasympathetic mediated
mediated
defecation reflex so
you got to calm down a little bit in
order to do this
the parasympathetic nervous system is
going to cause the
internal anal sphincter to relax if
you're not calm you're not going to do it
it
all right so gotta calm down some people
i've talked about how they can't go to
the bathroom anywhere but at home that's
because they can't calm down enough
because it lets us flow so the
defecation reflex is going to occur when
something hits it
now just a little summary here uh
i'm not going to read every single one
of these to you but i do want you to
make sure that you know about the parts
elementary canal
oral cavity pharynx esophagus stomach
small test and large intestine
and what each part is doing so
definitely want to make sure that you know
know
the functional roles of each one of
these parts
the next part is the pancreas the
pancreas got both endocrine and exocrine functions
functions
in endocrine secretions the hormones
insulin glucagon affect most cells in
the body
we've already talked about this this is
where you know you insulin secrete
whenever you eat
gluten secreted when you don't eat but
you also have
exocrine secretions these are enzymes
primarily by clusters of acid in our cells
cells
what happens is that they empty into the
elementary canal emptying through the duodenum
duodenum
the main pancreatic duct is going to
travel down the middle of the pancreas
where it receives the secretions from
the acid ourselves and they're going to empty
empty
into the duodenum and what that's going
to do
is to help neutralize some of the
the stomach acid and help start the
digestive process here
you also have a smaller accessory
so what the pancreas does is to secrete
pancreatic juice
this is collective secretions of
pancreatic acinar and duct cells
and you've got again water and
bicarbonate ions
digestive proteins things like that the
bicarbonate ions that are present there
help make the pancreatic juice alkaline
what this is doing
is to protect your stomach from the duodenum
duodenum
from the stomach acid acids coming from
the stomach
the digestive enzymes secreted by acinar cells
cells
catalyzed reactions that digest all four
of your types of organic molecules
carbohydrates proteins lipids nucleic
acids are going to be helped to start
digestion here you got to get you got to
get these
into your body the best way you can
that's how you're able to do that
is by these digestive enzymes
now the pancreatic secretion occurs as a
basal root between males
but during eating it's going to rise
because you're
you've thought about food and hormonal
stimulation is going to make it
start happening more next we're going to
talk about the liver
now liver is again one of our accessory
organs of the pancreas is
and the liver sits on the right side of
your body
and you have lobes to it right and left
lobes and you also have the
caudate and quadrate lobes of the liver
so you've got four lobes
the way you can remember the caudate and quadrate
quadrate
lobes is that the
caudate lobe is next to the inferior
vena cava so caudate
cava c and c that's how i remember
that's where that's at
the quadrate lobe of the liver is right
next to the gallbladder which looks like
a backwards q the g so that's how i can
kind of remember uh where each one is located
located
call date next to the vena cava quadrate
this is also a picture what you're going
to look at in lab
of the lobules of the liver these are
the units that the liver uses to be able to
to
detoxify your blood now what happens is
your blood goes through here
on its way out of the intestine it comes
through here and then it gets filtered
so anything that's in there
that's nasty it's going to be filtered
out including alcohol stuff like that
so this is where it comes in you can see
that on the picture it comes in through the
the
the artery it gets shuffled through
these liver lobules
and it finally goes back out the the
portal venue
now what the liver does is actually a
lot of things it has one of the most
diverse sets of functions of any organ
in the body
it releases both endocrine and extrican signals
signals
and the majority of what it does is to
is to convert chemicals harmful
chemicals and things that are not
so harmful the main digestive function
is to produce bile
what bile does is to include water lipids
lipids
electrolyte compounds and what bile does
is to help you digest lipids
the lipids are are basically things that your
your
your body cannot digest lemon own the
bile is helped
to do that so a mechanism by which liver
excretes waste and other substances it
is kind of excrete
the liver produces bile continuously but
does not secrete it as
at a basal rate so it's in there it's
just not being secreted
at a basal rate
bile is derived from cholesterol
one of the biles main components is bile salts
salts
bile salts are actually amphiphilic
amphi means both philip means liking
they have both polar and nonpolar parts
this allows them to interact with both
lipids and the watering environment of
the small intestine
what they do is to coat lipids in the
duodenum and physically break them down
we call this emulsifying this is what
you have to be able to do to break fat support
support
you do the same thing whenever you put
gain your laundry detergent or if you put
put
dawn your dishwater it's going to break
the fats down so bile is
containing varying amounts of materials
that liver excretes
including cholesterol waste products and
now liver also secretes bilirubin the
bilirubin is a waste part that results
from the breakdown hemoglobin
by the spleen so
the breakdown turns
this these things into this yellow
pigment this yellow pigment urobilinogen
is responsible for the color of urine
it's the reason why it's yellow
so that's the reason why you pee pee
when it's yellow
the liver also performs a host of other
functions including nutrient metabolism
which processes the nutrients obtained
from the diet detoxification which is
really important because if we drink
something that's harmful to us
we uh get detoxified in the liver
especially alcohol
and it's secretion the liver excretes
bilirubin along with
other substances that it will process
uh like antibiotics which modifies
substances that can be secured by the
kidneys so
a lot of times before you go on a medication
medication
they will check your liver enzymes to
see what levels they're at
because if they are bad you may have to
wait because medications that you take
into your body
that are not natural your body's going
to try to break them apart
so if your liver enzymes are too high
and it's messed up and you can't take them
them
especially things like cholesterol medication
the gallbladder is a small sack that
sits on the back of the liver
and this receives most of the bile from
the common hepatic duct
it's going to store a bile concentrate
it and release it when stimulated
now if you are eating a high fat diet
then you're going to be using a whole
lot of this and sometimes it can become crystallized
crystallized
we call those gallstones which is very unpleasant
unpleasant
the bile release is stimulated by
something called coleus cystokinin cck
this can trigger the contraction of the
smooth muscle on the wall of the gallbladder
gallbladder
what that's doing is telling it to
now the cystic duct joins the common
hepatic duct
and to form the bile duct that's going
to going to empty down into
the duodenum
this is entering down a place called the
patio pancreatic sphincter
that means coming from the liver and
pancreas and the contents of the
pancreatic ampulla emptying duodenum at the
the
major duodenal papilla this is the place
where it comes in
and again the bile salts are going to
come into the duodenum what they're
going to do is help start breaking down
lipids but again if you have a lot high
fat diet and you precipitate this out
they can form these hard lumps called
gallstones and having gallstones
is very unpleasant i never had them you
know just me knocking on wood right there
there
i've never had them but i heard they're
extremely painful
and what happens sometimes you have to
get your gallbladder removed
and if that happens then you can
you really can't eat a whole lot of high
fat diet
because you won't be able to digest it
properly you still eat but you just
can't eat a big fat diet which is
actually good for you
you don't like that anyway so um the
gallbladder is is
and there's just a summary of
your accessory organs again teeth tongue
salivary glands pancreas liver gallbladder
gallbladder
definitely want you to know what each
one of those does for you so the
functional role is on the right side of
the column here
now the next part we're going to talk
about we're going to talk about the
actual processes of digestion
and absorption we're going to talk about
how we actually get
these things into our small intestine so
the only way this is going to occur is
if you break down your food
until the only individual nutrient
molecules remain so the two types of
digestion mechanical digestion a
chemical detection
mechanical digestion is which food is
actually physically broken down
mastication in the mouth turning in the
stomach supplementation the small intestine
intestine
they're all the same mechanisms they're
churning and pummeling the food so it's
going to be broken
chemical digestion is when you actually
use enzymes to break
specific bonds in a single type of
nutrient so they're both very important
parts of digestion
but what happens is that they're
actually carried out a different way one
is by actually
physically touching the food the other
is by having chemicals digested
now most enzymes catalyze hydrolysis reactions
reactions
which means they use water to break
things down
so that explains why you need so much
water so
you should drink a lot of water because
the water is a very key component of
breaking down reactions and big
molecules and the small ones
the more water you have the better
nutrition you're going to have
so we call this enzymatic hydrolysis
they're going to speed up reactions with that
that
so the more water you drink the easier
it's going to break down big molecules
that's why i tell you drink a lot of
water because
you will lose weight if you drink more water
digestion begins in the mouth where they
help to salivary amylase
uh not really a whole lot going on here
celery imlace is um going to break it
down in your mouth
but not long enough for it to really
have an effect
so celery amylase digestion continues in
the stomach but usually your stomach
acid is going to
burn that before it can only do anything
after you
get out of the stomach you encounter
another type of
of amylase called pancreatic amylase and
what that does
help break down the starches after
they've encountered the
the stomach now what happens here
when your uh polysaccharides have been
broken down
enter into your into your in small
intestine from your stomach
they're going to be attracted to brush
border enzymes
now what that means is that the enzymes
are going to break them down to even
smaller things
the brush border enzymes are going to
catalyze the breakdown of these
disciplines and the monosaccharides
so things like glucose and fructose and
what's happening if you look
versus number the sodium potassium pump here
here
is exchanging sodium potassium in your
cell membrane that's creating a gradient
that's creating a positively charged
gradient so you're trying to get these
these sodiums to pull into the cell
when you pull the sodium in the cell it
pulls in the glucose too
so that's how you're able to pull those
cells pull that into the cells from the
lumen of the small intestine
into the actual cells and then through
into the blood
so that's how you get glucose into your
it's a gradient it's going to drive
secondary active transport via the
sodium glucose co-transporter that means
that you
you take glucose and sodium at the same time
time
fructose does not bind to that it can't
so it's got to go through
facilitated diffusion all three of them
will cross the basal side of the
enterocyte membrane into the blood so
they'll go
straight from the small intestine
to the liver for processing because
whatever is toxic in there needs to be
taken care of
now chemical digestion of proteins does
not begin to let you systemic
so you don't have any protein digestion
in your mouth that's encountered pepsin
chi cells or gastric glands produce the
inactive precursor pepsinogen
pepsinogen requires a ph of about two to
become pepsin
and it's inactivated at ph seven so it's
got to be inner stomach
now activated pepsin catalyzes reactions
that digest proteins and small
polypeptides like peptides and sometimes
even amino acids
but pepsin reactions only catalyze about
10 to 15
proteins in the ingested food
the majority of protein digestion takes
place in the small intestine
with the help of pancreatic enzymes in
brush border enzymes
the first pancreatic enzyme become
activated is trypsinogen
which becomes trypsin when it's
activated on the intestinal brush border
carbohydrate absorption this occurs the
same way
the sodium potassium pump is going to
create a gradient and it's going to pull
the amino acids through and pull sodium
through so it's the same way
carbohydrates and proteins are actually
pulled into your cell in exactly the
same way through sodium pump
so for your next discussion question
i would like you to name at least three
things i
don't i want to look it up i want you to
tell me what you think three reasons
why sodium is so important
for your body for your health so i want
you to name one that's a digestive
function you can use the one here on the screen
screen
and i also want you to think about why
sodium is so incredibly important
now again just like the carbohydrates
after you get amino acids
into your blood they're also sent to the
now the majority of lipids now
taken in the diet are triglycerides
which consists of three fatty acid
molecules by the glycerol molecule
this will not work the same way that
your protein and carbohydrates work
the nonpolar lipids stick together
forming large globules if you break them up
up
they go back together so you can break
some of them down mechanical digestion
mastication churning
but they're going to come back together
so the bile salts
you have to use them to emulsify the
lipids this gives digestive enzymes
enough surface area in which to work to
efficiently digest them
they're actually very hard to digest
because there's such a different
so what happens is that lipids are
broken apart
and then the lipid droplets come back
together and then you got to
to use the bile salts from the lipid
droplets to
emulsify them to use them to where they
can't do that so pancake lipase is going
to digest the lipids and the fatty acids
and monoglycerides
the bile salts are going to help them form micelles
form micelles my cells are just a type of
my cells are just a type of lipid uh
thing that's going to be digested it's it's a
it's a i got bile salt surrounding it so it
i got bile salt surrounding it so it will actually be able to be
will actually be able to be digested easier so my cells are just
digested easier so my cells are just little structures
little structures uh that helps the digest lipids stay
uh that helps the digest lipids stay together so it's very important
now the micelles enter the lipids um and then they break apart and then
um and then they break apart and then they reassemble right back into
they reassemble right back into triglycerides and you're probably
triglycerides and you're probably wondering
wondering why in the world did i just break these
why in the world did i just break these things apart to be able to put it right
things apart to be able to put it right back together yes i'm sure
back together yes i'm sure but that's what they do the my cells are
but that's what they do the my cells are going to enter
going to enter your intestinal cells it's going to
your intestinal cells it's going to break apart the bile salt is going to
break apart the bile salt is going to pop off
pop off and they're going to reassemble in
and they're going to reassemble in triglycerides and then you're going to
triglycerides and then you're going to package those in the chylomicrons from
package those in the chylomicrons from that point
that point the column microns will exit and go into
the column microns will exit and go into the lacteals
the lacteals now why do you think that you can't
now why do you think that you can't take these directly into your
take these directly into your bloodstream well because they're not
bloodstream well because they're not water-soluble
water-soluble they're not water-soluble so you cannot
they're not water-soluble so you cannot put lipids into your blood
put lipids into your blood because your blood's water-soluble they
because your blood's water-soluble they would they wouldn't mix so it would be
would they wouldn't mix so it would be bad for you to do that you're gonna put
bad for you to do that you're gonna put these column microns into your
these column microns into your intestines
intestines through the lacteals that way they can
through the lacteals that way they can actually be processed
actually be processed now lipids again are not delivered okay
now lipids again are not delivered okay to the to the liver
to the to the liver because the hepatic portal vein delivers
because the hepatic portal vein delivers electro bile sauce to liver where they
electro bile sauce to liver where they used to make new bile
used to make new bile so the lipids travel through thoracic
so the lipids travel through thoracic that where they join the blood and rest
that where they join the blood and rest of the lymph so
of the lymph so they don't go there quite just yet as
they don't go there quite just yet as the chylomicrons travel through blood
the chylomicrons travel through blood capillaries they're removed in processes
capillaries they're removed in processes where they can be used for different
where they can be used for different purposes it's really a bad thing to eat
purposes it's really a bad thing to eat a whole lot of actually
a whole lot of actually i mean it's it you can't use it for
i mean it's it you can't use it for energy and your body stores them as
energy and your body stores them as energy
energy but you already have so much of this
but you already have so much of this that's really not necessary to eat a
that's really not necessary to eat a whole lot of it
and this little summary so far we've got carbohydrates proteins those are broken
carbohydrates proteins those are broken down the same way brush border enzymes
down the same way brush border enzymes co-transporter sodium
co-transporter sodium uh co-transfer lipids broken down small
uh co-transfer lipids broken down small lipids and the micelles and then
lipids and the micelles and then reassemble the fatty acids
reassemble the fatty acids monoglycerides
monoglycerides that's how we're able to be able to do
that's how we're able to be able to do that and the other thing about lip is i
that and the other thing about lip is i do want you guys to kind of think about
do want you guys to kind of think about they're actually really big molecules
they're actually really big molecules that's the reason why we have a lot of
that's the reason why we have a lot of lipid in our stomach
lipid in our stomach as far as you know weight weight gains
as far as you know weight weight gains because
because they're big molecules
now digestive nucleic acids we can eat nucleic acids
nucleic acids uh and we do and every time i eat
uh and we do and every time i eat anything that's got any kind of animal
anything that's got any kind of animal or plant product we do
or plant product we do and the enzymes called nucleases are
and the enzymes called nucleases are gonna break them down they break them
gonna break them down they break them down to any
down to any individual nucleotides further digestion
individual nucleotides further digestion occurs via brush border enzymes they
occurs via brush border enzymes they remove the phosphate group and
remove the phosphate group and and uh eric's they are absorbed by
and uh eric's they are absorbed by active transport uh fairly easy
active transport uh fairly easy um don't think about this you
um don't think about this you i mean it's not you you use them don't
i mean it's not you you use them don't be wrong you use i'm going to tell you
be wrong you use i'm going to tell you that you do
that you do use them they they're not used for
use them they they're not used for energy though
energy though so any any nucleic acid that you eat
so any any nucleic acid that you eat you incorporate you can incorporate back
you incorporate you can incorporate back into your own body you know you can use
into your own body you know you can use it
it but there's no you're not going to be
but there's no you're not going to be able to get any energy out of that
able to get any energy out of that that's not what it's for
that's not what it's for now the elementary canal also absorbs
now the elementary canal also absorbs water electrolytes and vitamins this is
water electrolytes and vitamins this is actually really easy because these are
actually really easy because these are already small
already small this occurs in the small intestine but
this occurs in the small intestine but most of it occurs in large intestine too
most of it occurs in large intestine too on average about nine liters of water
on average about nine liters of water enter the small intestine
enter the small intestine every day about two of that water are
every day about two of that water are ingested
ingested the rest of it is secreted of the nine
the rest of it is secreted of the nine liters eight liters are absorbed into
liters eight liters are absorbed into the small intestine
the small intestine the remaining is used in feces
the remaining is used in feces so what should you be doing every day
so what should you be doing every day drinking as much water as you can
drinking as much water as you can because in order to have good digestive
because in order to have good digestive health you have to have
health you have to have water be able to do it without that it's
water be able to do it without that it's not going to be so good for you
not going to be so good for you so definitely definitely try to drink as
so definitely definitely try to drink as much water as you can
much water as you can it will really help your health
it will really help your health digestive health weight loss
digestive health weight loss and the more water you drink the better
and the more water you drink the better off you are
vitamins vitamins water soluble vitamins fat soluble vitamins
fat soluble vitamins water-soluble vitamins are things that
water-soluble vitamins are things that are going to be
are not the ones that are fat soluble so like vitamin b vitamin c
so like vitamin b vitamin c things like that are water soluble
things like that are water soluble and then fat soluble or lipid nonpolar
and then fat soluble or lipid nonpolar these are going to
these are going to package into my cells these are things
package into my cells these are things that are greasy vitamins like vitamin d
that are greasy vitamins like vitamin d e k a those are all different types of
e k a those are all different types of vitamins that are in fact
vitamins that are in fact uh lipid soluble so we have different
uh lipid soluble so we have different types you know they do different things
types you know they do different things but
but i definitely want you know the two types
i definitely want you know the two types of vitamins water soluble versus versus
of vitamins water soluble versus versus fat solid
here's the big picture of digestion food is ingested
is ingested into my bolus swallow reflex pushes it
into my bolus swallow reflex pushes it down the stomach
down the stomach the bolus turns the kind i don't i want
the bolus turns the kind i don't i want you know what chyme is
you know what chyme is kind comes out three milliliters um into
kind comes out three milliliters um into the small intestine
the small intestine uh there it hits juices from the
uh there it hits juices from the pancreas and liver
pancreas and liver the nutrients are digested absorbed if
the nutrients are digested absorbed if it's fat it goes in the lacteals if it's
it's fat it goes in the lacteals if it's not it goes into the bloodstream
not it goes into the bloodstream and then it goes to the large intestine
and then it goes to the large intestine and defecated out if it is not usable
you can you can think of this funny little cartoon it's just an accurate
little cartoon it's just an accurate representation of the digestive system
representation of the digestive system what actually kind of looks like you
what actually kind of looks like you know um
you know you see the stomach there in the in the intestines liver gallbladder
the in the intestines liver gallbladder those are actually really that's a
those are actually really that's a really good kind of representation of
really good kind of representation of what that kind of looks like
what that kind of looks like so for your last discussion question
so for your last discussion question i'd like you to tell me what you thought
i'd like you to tell me what you thought was most interesting about this chapter
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