Health and medicine
- Meet the gastrointestinal tract!
- Small intestine 1: Structure
- Small intestine 2: Digestion
- Small intestine 3: Absorption
- Hepatic lobule
- Biliary tree
- Exocrine pancreas
- Endocrine pancreas
- Colon, rectum, and anus
- Control of the GI tract
Explore the structure and function of the liver's hepatic lobule, focusing on the portal triad and its role in nutrient and oxygen supply. Learn how hepatocytes extract nutrients for metabolism and storage, and how blood is returned to the heart for oxygenation. Created by Raja Narayan.
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- Does the fact that the branches of the portal vein are called sinusoids have something to do with shape? Because sinusoidal refers to a trigonometric wave like sine/cosine.(14 votes)
- Surprisingly, sinusoids are not named after a sinusoidal curves nor are sine waves named after sinusoidal vessels. However both have the same root: the Latin sinus, meaning a curve, a fold, a gap or a pocket.
Sinusoid blood vessels are one of three types of capillary: continuous, fenestrated and sinusoid. These labels refer to the type of barrier they form. Continuous capillaries have no gaps between the cells or the basement membrane. Fenestrated capillaries (from the French, fenestra, meaning "window") have small pores (on the order of 80 nm) in the cells, allowing the diffusion of small molecules and proteins out of the blood. Sinusoidal capillaries have large gaps between the cells and in the basement membrane (around 10 - 25 μm) that surrounds the capillary. This allows red and white blood cells to pass in and out of the capillaries. Here "sinusoidal" refers to the gaps in the capillary.
Sine waves are called that just because they are curves. Sinuses are so-called because they are air-filled cavities (or pockets) in the head.(48 votes)
- does the green dot from the PORTAL TRIAD that surrounds the hepatocytes do anything? You explained what the light blue / cyan and red dots did, but i don't think i caught what the green dot contributed. Thanks again(7 votes)
- Yes it does :)
At1:10he say that they will form the common hepatic duct.
Essentially they will collect all the waste products the liver want to excrete into the feces and collect the bile acids for digestion.
Then they will go towards the intestines and empty their content there.(9 votes)
- Is liver fully solid, or hollow? (Or spongy, like lungs?) By the way, hepatic lobule looks confusing to me. What do hepatic cells actually do? Is hepatic lobule simply these cells surrounded by blood vessels, or... ?(5 votes)
- Hello :)
I know this is not mentioned in the video though, but they sure are in my textbook! What are Canals of Hering, Interlobular bile ducts and Interlobar bile ducts? (I am especially confused with Interlobular and Interlobar ducts; are they the same?)
Thank You! :D(5 votes)
- How do the metabolic products that are broken down in the liver reach the other parts of the body?(3 votes)
- The majority of the products broken down by the liver will reach the other parts of the body via the systemic circulation. The hepatic lobules have a central vein at the center of each lobule. These central veins combine to form hepatic veins which then drain into the inferior vena cava and, ultimately back to the heart.(3 votes)
- Does the common hepatic duct have a relationship to the hepatocytes?(3 votes)
- The common hepatic duct is where the bile produced by the liver is secreted. The hepatic duct joins the cystic duct from the gallbladder to form the common bile duct. However what produces this bile is the hepatocytes themselves. The bile is secreted into smaller spaces directly outside the hepatocytes called canaliculi. These canaliculi join together to form the hepatic duct.(2 votes)
- At2:23in hepatic lobules topic How can the branches of portal vein(sinusoids) transport oxygen to hepatic lobule
because portal veins transport nutrients ?(3 votes)
- the video at2:17says that sinusoids are the portal veins which are rich in nutrient and proper hepatic artery are rich in oxygen.... i think you should watch the video again......... hope this helps(1 vote)
- Aren't the arteries and veins made up of cells also...... and if they are made up of cells then don't they need oxygen and nutrients to survive..... from where do thay get these nutrients from ?(2 votes)
- Cells making up blood vessels, arteries and veins, also have capillaries that deliver oxygen and nutrients so they survive. Red blood cells are the only cells I am aware of that can survive by anaerobic respiration in the body. All other cells have mitochondria and use aerobic respiration, which requires oxygen.(2 votes)
- I am confused. Shouldn't the central vein be called central capillary.(2 votes)
- I don't understand why there are portal vein and hepatic vein that carry two different functions - don't we just have vein that transport deoxygenated RBC and wastes back to the heart?(1 vote)
- Typically, in all other areas of the body, you are right. The aorta branches off to arteries, then arterioles, then capillaries, then venules, then veins, then the inferior vena cava, and to the heart. The digestive system is different in its circulation, as all the water soluble food that is absorbed into the intestinal epithelial cells goes to veins that feed into the portal vein and then the blood goes to the liver. So, the liver gets the first chance to take in glucose, small fats, and amino acids and use them to make things the body needs. Then the blood goes to the hepatic vein and to the inferior vena cava. Since the liver is doing work for the whole body, making albumin, clotting factors and compliment, it is good that it gets the first chance. But, it is also true that any toxin or poison is also going to go first to the liver, which explains how cirrhosis occurs due to the excessive intake of alcohol or liver failure occurs with the ingestion of a poisonous mushroom. https://en.wikipedia.org/wiki/Portal_vein(3 votes)
So we've talked about a lot of vessels here. The main three that we should focus on are these guys right here, the portal vein, the hepatic artery and the common hepatic bile duct. Together these three make what's called the portal triad. It's one of the structures that are very important to identify in surgery and also is seen very commonly in the liver, when we look at smaller cuts of the organ. So if we were to focus in on a smaller section, like that. And blow it up so we can get a better picture of what's going on here. We can see that the liver itself, this giant fatty organ, is split up into smaller pieces or units, that are called hepatic lobules, hepatic lobules. And in the hepatic lobule we'll have a whole bunch of our hepatocytes or single liver cells, that are hanging out, sitting around here. Surrounding these hepatocytes is going to be a representation of our portal triad. That includes a branch that was part of the portal vein. A branch that was part of the hepatic artery and then a branch that will come together to make the common hepatic duct. So those three that make up your portal triad. Now this portal triad isn't found in just one part of the hepatic lobule. In fact, there's a bunch of them that surround the hepatocytes and make this very familiar shape, you might recall from chemistry. So it's this six-sided ring that makes up the hepatic lobule. That has six units of the portal triad surrounding the hepatocytes. And this is how we get nutrient rich blood to enter into the hepatic lobule, so that way these hepatocytes, these liver cells, can extract nutrients for the metabolism or the storage of macro molecules. And of course, hepatocytes are just like any other cell in the body, they need oxygen to survive. And so, oxygen will be carried in from our proper hepatic artery. So we'll supply the hepatocytes with oxygen, we'll supply them with nutrients from these branches off of the portal vein. They're called sinusoids, I'll write that off right here. Sinusoids that come off the portal vein and finally after nutrients have been extracted, oxygens been extracted and we need to send this blood back into the hepatic vein, all of the blood will collect at this very center right here, very conveniently called the central vein. So the central vein that sits in the very middle of our hepatic lobule, will take our nutrient and oxygen poor blood and then coalesce into a hepatic vein that'll be sent off to the heart for oxygenation by the lungs, and then passed by the intestines to receive nutrients from the absorption process we talked about. So that's how our liver works.