The anatomy of the liver

So in this video, we’re going to cover where the liver is in your body, how it’s organised, and how it fits in with your other digestive organs. And we’re going to use Dave, here, to help us explain the anatomy to you. So the liver is your largest organ. It’s about a kilo and a half. Sort of three pounds. It’s about the size of a rugby ball, and about 1/50th of your body mass. It grows to fit your size. It’s made up of about 100 billion cells. And it’s your largest solid organ. So if I take out Dave’s lungs here, you can see the liver.

It’s separated into two different lobes, a right and left lobe, separated by this ligament here, the falciform ligament. And it’s closely associated with these other abdominal organs. And actually, if you turn it over, you can see there’s a depression where the kidney and the intestines actually press against the liver. It’s held in place by intra-abdominal pressure, by the diaphragm, and by the peritoneum. And it’s actually protected by a collagenous capsule, which just keeps the surface protected. If I turn the liver around, you can see the point where the blood enters and leaves the liver. And the liver is unusual in that it has a dual blood supply.

So you have oxygenated blood coming in through the hepatic artery, but you also have nutrient-rich blood, which comes directly from the gut, also entering by the portal vein. And then you have the exit where the bile that’s made in the liver actually comes out and enters the gall bladder. So this is the gall bladder here. You can see it’s sitting just underneath the liver at the back. It’s about 10 centimetres long. It’s like a little bag. And it stores about 50 millilitres of bile, which you make throughout the day. And it’s sort of squeezed and secreted into your intestine down here, as you need it when you eat. So it’s stimulated by the presence of food in the gut.

A little sphincter contracts and actually delivers this bile into the bowel where it can help you digest fat. So if we talk about the blood supply again, a little bit more, about 75% of your blood actually comes in via this portal vein. So this is the supply coming in from your intestines. Whereas about 25% of the blood is oxygenated and that’s what’s coming in through the hepatic artery. And the blood then enters through both these routes and mixes within the body of the liver before it actually drains and exits the liver via the inferior vena cava, and goes back up into the systemic circulation.

Now based upon this blood supply and this bile drainage, you can actually divide the liver into anatomical sections. So rather than just this left and right half, you can actually split up into separate segments, each of which has its own bile supply and blood supply. And this is really useful for surgery and treatment of things like tumours, because you can actually take out a portion of the liver, perhaps which has a tumour in it, with its own independent blood supply, and the remainder of the liver isn’t compromised. And we’ll talk about how the liver actually grows back, or regenerates, later on in the course. So I’ve covered the anatomy of the liver now.

But what we need to do next is talk about the microscopic anatomy of the liver. So the way that we would actually look at this is to take a sample of the liver that we can put under the microscope. And this is usually done by a liver biopsy. So what your physician would do is use a needle to actually take a sample. He would go through between the ribs here, and take a sample from this larger right half of the liver, which could then be preserved, put under the microscope. And then we can actually look at the cells and try and work out what’s happening.

So in our next video, we’ll have a conversation with one of the liver pathologists here in Birmingham, Professor Hubscher And we’ll move from looking at the large scale anatomy of the liver to the cellular level, so we can understand a bit more about what the individual cells which make up the liver are, and how they function.