The liver is one of five vital organs, which means it is necessary to keep you alive. The other vital organs are the brain, heart, lungs, and kidneys. Amazingly, only one third of your liver is needed to maintain normal functioning! This organ performs over five hundred vital tasks, and this video will discuss some of the most important ones!
The liver is the human body’s second heaviest organ! It has four lobes - right, left, caudate, and quadrate. These lobes contain 1 million hexagonally-shaped hepatic lobules. Lobules are the functional unit of the liver, meaning that they are the smallest structures capable of performing the liver’s tasks. Lobules are made up of hepatocytes.
A key task of the liver is to filter blood. At any given time, the liver contains 13% of your blood volume. Freshly oxygenated blood comes down from the heart’s aorta and enters the left and right hepatic arteries to supply the liver. Blood leaves the liver by the hepatic vein and goes through the inferior vena cava back to the heart. Then, circulation starts anew!
The liver also receives blood through the portal vein from the gastrointestinal tract. It filters this blood to remove pathogens and toxins like alcohol and drugs. The liver and kidneys are the only “detox” your body will ever need! The filtered blood leaves the liver via the hepatic vein!
The liver filters more than just toxins. It also houses Kupfer cells, which are a kind of immune cell called a tissue macrophage. Kupfer cells make up 80-90% of the body’s tissue macrophages! Kupfer cells remove and destroy old, or senescent, red blood cells. Red blood cells live for around 120 days before this happens. Kupffer cells destroy red blood cells through phagocytic action, and the hemoglobin within them gets recycled. Kupffer cells also destroy pathogens, which can enter through the portal vein. They sense bacteria or endotoxins, which are toxic substances bound to the bacterial cell wall and released when the bacterium ruptures or disintegrates. Upon detection, the Kupffer cells attack, releasing cytokines, nitric oxide, and oxygen species to destroy the pathogens!
The liver also produces many of the clotting factors needed to help seal your wounds. Clotting factors are the reason you don’t bleed to death when you get a small cut! Coagulation, or clotting, is the process by which blood thickens from a liquid to a gel. Coagulation is part of hemostasis, the process that causes bleeding to stop. Hemostasis begins when blood comes in contact with a foreign surface, which happens when a blood vessel is damaged.
Yet another role the liver plays is for digestion! It helps digest fats by making bile and helps with vitamin absorption! Bile gets produced by hepatocytes within liver lobules and then gets stored in the gallbladder. From there, it goes into the duodenum, where it helps to digest and absorb fat and fat-soluble vitamins! Bile breaks down fats into fatty acids, which can be taken into the body by the digestive tract. Vitamins A and D are fat-soluble vitamins that depend on bile salts for absorption.
The liver and the pancreas work together to control blood glucose levels. When glucose levels are low, the pancreas releases glucagon. Glucagon breaks down liver glycogen to glucose, which is released into the bloodstream, raising blood glucose levels. When blood glucose levels are high, the pancreas sends out insulin. Insulin stimulates the liver to store glucose in the form of glycogen. It also tells the body’s cells to take glucose from blood, either to use as energy or to store it for future use. This results in lower blood glucose levels in the bloodstream.
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