Liver Anatomy: Lobules, Blood Supply, and Micro‑Circulation

Name: Liver Lobules (Portal Triad)
Uploaded: 2020-07-23T21:00:27+00:00
Duration: 10 min 55 s
Channel: Dr Matt & Dr Mike
Description: Summary and key takeaways on Liver Lobules (Portal Triad): Summary & Key Takeaways, covering Liver Blood Supply The liver receives blood from two sources. The

Dr Matt & Dr Mike

Jul 23, 2020

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10 min video

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2 min read

YouTube video ID: vfA-WD5tkDA

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The liver receives blood from two sources. The portal vein delivers nutrient‑rich blood from the colon, small intestines, pancreas, and stomach, accounting for about 70 % of total flow and rising to roughly 90 % after a meal. The hepatic artery supplies oxygenated blood, complementing the portal input. Blood from both vessels drains into the central vein of each lobule, then exits via hepatic veins to the inferior vena cava.

Hepatic Lobules

Each liver contains 50,000 to 100,000 hexagonal lobules, the organ’s functional units. At every corner of a lobule, branches of the portal vein and hepatic artery enter together, forming the portal triad. Blood travels inward through sinusoids toward the central vein, which collects the mixed blood for removal from the organ.

Micro‑environment and Exchange

Sinusoids are specialized capillaries with porous endothelial lining; the large gaps let proteins and other substances pass freely. Between the endothelium and hepatocytes lies the space of Disse, an interstitial compartment that receives proteins released by hepatocytes and drains into lymphatic vessels. Kupffer cells, resident macrophages, sit within the sinusoids and engulf invading pathogens. Hepatocytes perform metabolic and synthetic tasks: they store roughly half to two‑thirds of incoming nutrients, detoxify harmful compounds, and synthesize plasma proteins such as albumin, which enter the space of Disse for transport back into the bloodstream.

The Portal Triad

The triad at each lobular corner comprises a branch of the portal vein, a branch of the hepatic artery, and a bile duct. Bile ducts collect bile—containing cholesterol, electrolytes, and water—produced by hepatocytes and convey it toward the gallbladder and intestine. Lymphatic vessels accompany the triad but are not included in its name.

Integrated Flow and Function

Blood follows a defined sequence: hepatic artery and portal vein → sinusoids → space of Disse → hepatocytes (processing and storage) → central vein → hepatic vein → inferior vena cava. Simultaneously, hepatocytes generate bile that drains into the bile ducts of the portal triad. The porous sinusoidal endothelium distinguishes liver micro‑circulation from typical capillary networks, enabling extensive protein exchange and efficient metabolic processing.

Takeaways

The portal vein supplies about 70 % of liver blood flow, increasing to roughly 90 % after meals, while the hepatic artery provides the remaining oxygenated blood.
Hexagonal hepatic lobules serve as the liver’s functional units, each containing a central vein and a portal triad at its corners.
Liver sinusoids feature porous endothelium that permits protein exchange with the space of Disse, where hepatocyte‑derived proteins enter the bloodstream.
Kupffer cells within sinusoids act as macrophages, ingesting pathogens that attempt to cross the endothelial barrier.
Bile produced by hepatocytes drains into bile ducts of the portal triad, while lymphatic vessels accompany but are not part of the traditional triad.

Frequently Asked Questions

Why does the portal vein provide most of the liver's blood flow?

The portal vein carries nutrient‑rich blood from the digestive tract, delivering the majority of substrates needed for hepatic metabolism. Its large volume—about 70 % of total hepatic inflow, rising to 90 % after meals—ensures the liver receives ample material for processing, storage, and detoxification.

How do liver sinusoids differ from typical capillaries?

Liver sinusoids possess a porous endothelial lining with large gaps, allowing proteins and other macromolecules to pass directly into the space of Disse. This contrasts with standard capillaries, whose tighter junctions restrict such exchange, making sinusoids uniquely suited for the liver’s extensive metabolic and synthetic functions.

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Helpful resources related to this video

If you want to practice or explore the concepts discussed in the video, these commonly used tools may help.

Human Liver Anatomy Medical Study Model Recommended

A 3D anatomical model provides a tactile way to visualize the hexagonal lobule structure and portal triad arrangement discussed in the lecture.

Amazon →

Human Histology Textbook With Liver Diagrams

A histology textbook contains high-resolution microscopic images of sinusoids, hepatocytes, and portal triads, reinforcing the lecture's focus on cellular structure.

Amazon →

Large Whiteboard For Educational Instruction

The speaker uses a whiteboard-style approach; a personal whiteboard helps students replicate the diagrams of blood flow and lobule anatomy to improve retention.

Amazon →

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Full Transcript YouTube

hi everybody dr mike here in this video
we're going to take a look at liver
lobules and focus on what we call the
portal triad so
what we have is when it comes to the
blood supply that goes to the level we
already know
that we've got for example the hepatic
artery
coming in so let's write that down
hepatic
artery bringing oxygenated blood to the
liver and we've also got
the portal vein coming in
which is bringing all these nutrients
that are draining from the digestive
viscera so this includes
coming from the colon coming from the
small intestines coming from the
pancreas for example coming from the
stomach
we've got all these various vessels
draining into the portal vein
going to the liver so unlike other
structures the liver has both the
hepatic artery and portal veins
entering it now when we look at the
amount of blood flow around about 70
percent of this blood
is coming from the portal vein and that
increases to about 90 percent
after a meal because obviously
nutrient-rich blood needs to get to the
liver for processing which we're going
to talk about in a second
the other thing we need to talk about is
the fact that the liver
like every other structure has venous
vessels
coming out and this is what we call the
hepatic vein
and the hepatic vein ends up becoming
the
inferior vena cava
which obviously goes back to the heart
alright
question is what happens to these two
vessels when they enter the liver well
the liver is comprised of what we call
lobules and there's between 50 000 to
100
000 lobules in the liver now the lobules
are the functional
units and they're hexagonal in shape
so what does that mean one two three
four five six sides so you've got
all these hexagonal shaped lobules
throughout the liver like i said fifty
thousand to a hundred thousand of them
and they do all the work so
what we find is that for example the
portal vein will come in
and branches of the portal vein will go
to
every single corner of each of these
liver lobules
so you're going to have a dedicated
branch of the hepatic
of the portal vein i should say sorry
going to every one of these liver
lobules
and so forth and the same actually
happens with the hepatic artery
you're going to have a branch of the
hepatic artery
at every corner
of these liver lobules as well
so all these branches coming through
all right now interestingly right in the
middle of these lobules is a central
vein and this is where both the hepatic
artery and the portal vein
drain into now it's going to be very
difficult looking at it here so i'm
going to draw this
up draw a big hepatic
lobule and let's see what happens
so we know that we have at every corner
a big portal vein
branch and we've got
one of the hepatic arteries branched
at every corner
all right next thing is both of these
two vessels
the blood comes together remember what's
in each blood for the portal vein
high nutrients for the hepatic artery
high in oxygen then what happens is this
they both drain together
and this happens at every corner
every corner
and what you end up getting
i miss the one down the bottom that's
right i'll draw that up now
and what we get is what we call the
central
vein now this central vein talk about in
a sec but it drains
and comes together and all of these
central veins
come together and merge into the
hepatic vein and then that goes to the
inferior vena cava all right
so what happens is this you're going to
have
the blood high nutrients draining into
this
area here now this area is called the
sinusoid
the sinusoid and the sinusoids important
because this is where this blood is
mixing and what you're going to find
lining now let's just focus on this one
for example lining the sinusoid
you have endothelial cells
endothelial cells just like the types of
cells you find
lining blood vessels capillary beds for
example
but the liver is a little bit different
because even though it capillaries
the endothelia are porous so there's
holes then those holes
usually aren't big enough to let things
like proteins out but
at the liver they are so there's big
gaps
at these sinusoids and they're big
enough to let through a whole bunch of
substances
not big enough to let white and red
blood cells out but they are big enough
to let
proteins out and this is important
because this blood that's now
mixing here
will also be leaving the sinusoids
now when they leave the sinusoids
there's another
cell type that we need to talk about
which is sitting
here and they're these plate-like cells
and they're going to be on either side
and you're going to find them i'm going
to draw it up here as well because this
is important to show
and here
now these are the hepatocytes
these are the cells that do most of the
work in the liver so what's happening
is that the hepatic artery and the
portal vein drain into the sinusoids
they're very porous the fluid leaks out
that contains all that remember it's
going to contain nutrients
it's going to contain even some bacteria
coming from the digestive viscera
it's going to contain a whole bunch of
substances now
as it comes through and drains through
these porous little holes first thing is
the endothelia are dispersed between
them
they have these little cells
called kufa cells
so these are
kupha cells i've probably spelt that
wrong but the kuffer cells are basically
macrophages
and so what they do is any invading
pathogens that shouldn't
drain into the into this space here
which i'll talk about in a sec
they gobble up and get rid of now this
space
between the endophilia
the endothelial cells and the
hepatocytes
this space in between is called the
space of
disse the space of dissi okay
now you've got this fluid with
substances draining to the space of dc
and this is what happens
this fluid then gets taken up
by the hepatocytes
now it's nutrient rich so it's going to
contain carbohydrates it's going to
contain proteins it's going to contain a
little bit of fat
and what it's going to do is it takes it
up and the hepatocytes store around
about half to two-thirds
of these nutrients now what they also do
is they play a role in detoxification of
substances and
hepatocytes also produce things they
also produce proteins like albumin for
example
which means if they're producing things
they're releasing things and they
release things
into the space of dissi
so it goes in both directions and what
happens with the albumin for example
is it's going to move back into the
sinusoid
and then drain into the central vein
okay so you've got oxygen
you've got nutrients coming through the
sinusoids moving through the porous gaps
of the endothelia
hopefully the kuffar cells they take
their macrophages
they ingest any pathogens that shouldn't
move through it goes into the space of
dissing then the hepatocytes take it up
and decide what they want to do with it
they'll store stuff or
they'll produce stuff themselves and go
in the opposite direction
anything that's left is going to drain
to the central vein however
some things that move into this space of
disease
don't go in either direction and what
they do
is they drain in this direction
and this becomes lymphatics
this becomes lymph and this lymph
obviously forms a lymphatic
vessel so you've got three vessels here
at the moment there's one more vessel i
know it's called the portal triad three
but there's actually one more we need to
talk about
we haven't spoken about what these
hepatocytes do in the space between the
hepatocytes
what they end up doing is they can
produce
something called bile now bile i've done
a video on it is a collection of
cholesterol electrolytes water for
example
and then this bile
will drain in this direction into bile
ducts
and so what we end up having is
these bile ducts form another vessel
so you've actually got four vessels here
and the vessels
you've got two going in that direction
that's going to be the hepatic artery in
the portal vein
two going in that direction that's
lymphatics and bile
and it's called the triad because they
don't usually include the lymphatic
vessels associated with it and so this
is what's actually happening
at this space anything that drains into
the central vein like i said before
culminates together with other veins and
that turns into the hepatic vein
and then goes into the inferior vena
cava so what we've got here
is an introduction to the hepatic
lobules
and also the portal triad