0:00 In this video we're going to look at the livers, the liver anatomy and its 0:18 blood supply. 0:22 The liver is the largest internal organ in our body. 0:26 It lies in close proximity to other organs such as the gallbladder which is 0:30 under it and 0:31 the stomach which is to the left of it. 0:36 The liver is about 1.2 to 1.6 kilograms in healthy adults. 0:42 It is located in the right side of the body under the lower ribs. 0:49 The liver can be seen as though it's made out of two major lobes but it's 0:52 actually 0:52 four lobes of unequal size. 0:56 Now the organs that are in close proximity to the liver is a gallbladder which 1:00 actually 1:01 connects with the liver. 1:02 The bile duct comes from the liver and the gallbladder and the cystic duct 1:05 coming from 1:06 the liver. 1:07 These are important in the bile system which we'll look into later on. 1:13 The liver actually has a lot of blood supply in order to be oxygenated and in 1:19 order to receive 1:20 nutrients. 1:21 So two important things, oxygen and nutrients. 1:26 If we look at the liver's blood supply, here we have the archery, the aorta 1:31 coming from 1:32 the heart which brings oxygenated blood into tissues, body tissues. 1:40 Here there's this capillaries of general circulation where the tissues will 1:44 then use 1:44 up the oxygen and now this blood supply will be deoxygenated, it'll be low in 1:50 oxygen concentration. 1:52 This deoxygenated blood supply will go back to the heart through the inferior v 1:57 ena cava. 1:58 Now organs found on the bottom half of our body are the liver, stomach, spleen 2:06 and also 2:06 intestines. 2:08 The aorta coming from the heart gives oxygen and blood to all these organs. 2:14 The liver, stomach and the intestines. 2:19 The artery going into the liver is known as the hepatic artery and this gives 2:23 the liver 2:24 oxygenated blood, it gives the liver oxygen to function. 2:28 The artery giving oxygen to intestines is known as the mesenteric artery and we 2:33 won't really 2:34 focus on this. 2:36 Now what's important to know is that once the spleen, stomach and intestine has 2:41 used 2:41 the oxygen from the blood supply, the blood supply will be deoxygenated and 2:45 this deoxygenated 2:46 blood supply will be veins and actually this vein will not go back to the heart 2:50 but will 2:51 go towards the liver as a big vein known as the portal vein and these veins 2:57 carry nutrients 2:58 from the stomach, spleen and intestines and that is how the liver receives 3:04 nutrients. 3:05 So we see that we have the hepatic artery and we have the portal vein, one of 3:10 them bringing 3:10 oxygen and the other bringing in nutrients and then the liver, once it's used 3:15 all these 3:16 oxygen and nutrients, it will, there will be another vein leaving the liver 3:21 known as 3:22 the hepatic vein which connects to the inferior vena cava which then goes back 3:27 to the heart. 3:29 So let's look at this diagram in a bit more complex detail by looking 3:32 specifically at 3:33 the liver. 3:35 So here we have the liver, the aorta brings in oxygenated blood to the liver, 3:40 through 3:41 the right, left and right hepatic artery, so again this is oxygen rich blood 3:46 from the 3:47 heart and this actually only supplies about 25% of the blood supply to the 3:53 liver and then 3:54 we have the vein leaving the hum, the liver towards the heart and this is the 4:02 right hepatic 4:04 vein left, a middle hepatic vein and the left hepatic vein which connects to 4:07 the inferior 4:08 vena cava which then goes back to the heart. 4:12 And then we have the portal vein which brings in nutrients and this blood, and 4:17 this comes 4:18 from the intestines and this is about 75% of the blood supply going to the 4:23 liver. 4:23 So it's much more than the oxygen supply from the hepatic artery. 4:28 So again the portal vein brings in nutrients from the intestines, spleen and 4:32 the stomach 4:33 and then remember we also have the gallbladder here which connects to the liver 4:38 and this 4:38 stores bile for secretion and we have many bile ducts within the liver because 4:43 of this 4:43 connection. 4:46 Now let's have a look at how this hepatic cells are organized within the liver 4:50 and how 4:51 the blood supply with oxygen coming in, the portal vein with nutrients coming 4:55 in and the 4:55 hepatic vein leaving the liver all connect together and coincide within this 5:00 organized 5:00 structure. 5:01 Well the liver is over organized in a hexagonal sort of shape known as a lobule 5:07 like so. 5:08 Each lobule here contains many types of hepatic cells, liver cells. 5:15 In the center of the lobule we have the central vein which essentially connects 5:18 to the hepatic 5:19 vein which leaves the liver towards the heart and all these blue things coming 5:23 out of the 5:24 hepatic vein is the liver sinusoids and they run from the central vein into the 5:30 portal triad 5:31 so they connect with the portal triads. 5:34 What is the portal triad? 5:37 Well the portal triads consist of three things, the portal vein, the bile duct 5:45 and the hepatic 5:46 artery and so all these veins connect with each other and all of them all these 5:51 three 5:52 connect to the central vein and this is how the liver receives its oxygen, 5:56 receives its 5:57 nutrients and how it sends out bile from the liver into the bile duct so again 6:02 this is 6:02 known as the triad. 6:04 Hope this all makes sense. 6:06 Now it's also important to note that the liver contains special macrophages, 6:11 hepatic 6:11 macrophages known as coop first cells, I hope I pronounced that right. 6:16 Let's have a look at this section here and look at the organization in a lot in 6:20 a bit 6:20 your diagram. 6:21 So here what I'm drawing is the hepatic vein, essentially the central vein. 6:26 And here with the sinusoids which remember connects to the portal triad. 6:34 And the portal triads here are the bile duct, a branch of the hepatic portal 6:39 vein and a branch 6:40 of hepatic artery. 6:43 So bile duct, portal vein, hepatic artery and surrounding all the sinusoids and 6:47 all just 6:48 everywhere are the hepatic cells known as hepatocytes and so whatever comes to 6:55 the portal 6:55 vein and from the hepatic artery can be given into these hepatocytes and then 7:02 will be emptied 7:03 out into the hepatic vein which will then enter the heart. 7:06 Similarly cells which produce bile can then bring give it to the bile duct 7:12 which then goes 7:13 into the gallbladder. 7:16 So I hope that makes sense and remember that we have the liver macrophages 7:21 known as coop 7:22 first cells. 7:23 And these are important in the immune system. 7:27 Lastly, as I mentioned, the organization inside the liver are hexagonal shaped 7:34 lobules. 7:35 With the central vein being in the middle, the central vein can be also 7:38 referred to as 7:39 a hepatic vein because it essentially goes back towards the heart. 7:42 And then surrounding each corner of the hexagon we have the portal triads and 7:46 if you remember 7:47 what the portal triads are, they are the portal vein, the hepatic artery and 7:54 the bile duct 7:56 and they connect essentially to the central vein. 7:58 And with this connection the portal vein can then give nutrients to the hepat 8:02 ocytes and 8:02 the hepatic artery can give oxygen to the hepatocytes as well around here. 8:06 So I hope this was an enjoyable video. 8:08 In the next video we will look at the physiology of the liver. 8:10 Thank you.
