The liver is essential for our body

The liver (Greek: 'hepar') supports almost every organ in the body and is necessary for survival. It is both the largest internal organ (the skin being the largest organ overall) and the largest gland in the human body. Our liver has more than 500 different functions.

  • All the blood leaving the stomach and intestines passes through the liver. The liver processes this blood and breaks down the nutrients and drugs into forms that are easier to use for the rest of the body. These functions are strictly controlled by signaling cascades that regulate these processes.
  • Because of its strategic location and multidimensional functions, the liver is prone to many diseases constituting a serious problem world-wide. The liver plays a major role in metabolism (synthesis and breakdown of small and complex molecules, many of which are necessary for normal vital functions).
  • More than 5 million people in Germany suffer from diseases of the liver. Even more patients with liver diseases are diagnosed in the U.S. (approx. 45 million corresponding to 15 % of the population, according to the American Association for the Study of Liver Diseases). The liver has a remarkable capacity to regenerate after an injury, establishing interesting approaches for therapies. However, in order to be able to heal liver diseases, we need a better understanding of this organ.
  • The Virtual Liver Network is tackling this challenge. Our approach follows a concerted strategy unique in the scientific world and represents an effort to understand and to model a complete organ from the biochemical, cellular, to the whole organ level.
  • Author: Martin Golebiewski
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    The bile flow is produced in the liver and the bile digests fat in the duodenum

    The bile fluid is essential for the digestion of fats. The bile fluid is produced in the liver where the liver cells secrete it into a small space between neighboring hepatocytes, which forms the bile canaliculus, the smallest of the bile duct structures. The bile is transported through tube-like structures called bile ducts and is stored in the gallbladder.

  • After a meal, bile is excreted through the common bile duct into the first section of the small intestine (duodenum). In the duodenum, bile is mixed with the meal and covers fat (lipid) to form small digestible droplets.
  • Author: Johannes Eckstein

  • Image: Jill Zander and Iryna Ilkavets
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    Bile acids are recycled

    Bile acids are one of the components of the bile, which is produced in the liver in order to digest (surround, cover and break drown) fat (lipids) that we eat. In humans, between 0.2-0.6 g of the bile acids are produced daily.

  • This production exhibits diurnal rhythm with two peaking around 3 and 9 pm. The bile acids are stored in combination with other components in the gallbladder.

  • After each meal, the gallbladder contracts and the bile acids are emptied into the intestinal tract. After "having done their work" the bile acids are recycled out of the intestine back to the blood stream. From there they to the liver and then the gallbladder.

  • Thus, a bile acid pool of about 3 g is recycled 4-12 times a day. Some bile acids "get lost" during this recycling process, usually 0.2-0.6 g. They are replaced then by newly produced bile acids.

  • Author: Iryna Ilkavets

  • Image: Wikipedia, Frank Boumphrey
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    Glucose is the primary energy source for our organism

    Most cells and organs in the body use glucose as their primary energy source. It is delivered to glucose-consuming organs like muscles, the brain or fatty tissue though the blood. An important task for the whole organism is to keep the level of blood glucose high enough to fulfill the needs of the organism.

  • The glucose concentration after overnight fasting is normally around 90 mg glucose per 100 ml of blood. If the glucose level drops too much, the organism does not have enough energy to perform its regular functions.
  • On the other hand, if the organism is over-saturated at glucose levels that are too high it can result in the modification of proteins and damage to blood vessels. Therefore, a regulatory system exists, which keeps the blood glucose within the normal range. This process is called homeostasis.
  • The liver plays an essential role in glucose homeostasis, because it can produce glucose via a process called hepatic glucose production (HGP), or use glucose via hepatic glucose utilization (HGU). Glucose homeostasis is controlled by hormones, mainly insulin and glucagon, which are secreted by the pancreas and keep the blood glucose within the normal range despite large changes of external conditions. This is achieved by adapting HGU, HGP and the glucose consumption by muscles and fatty tissue.
  • Creative Commons License
    VLN glucose metabolism by Matthias Koenig is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
    Based on a work at http://www.charite.de/sysbio/people/koenig/

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    Each cell of our organism is able to accumulate lipid droplets

    Lipids are energy suppliers. Our organism has cells, called adipocytes that accumulate lipids. They are professional lipid storing cells. The lipids are stored there in the form of small and big droplets. The size of the lipid droplets in the cells depends on the amount of nutrients.

  • Besides the adipocytes, all cells in our organism are capable of accumulating lipid droplets, but in lower amounts than adipocytes.
  • The lipid droplets that are "swimming" in the blood are called circulating lipoproteins droplets. They comprise “good” HDL (high-density lipoproteins) and "bad" LDL (low-density lipoproteins) and VLDL (very-low-density lipoproteins). Blood levels of LDL and VLDL (along with cholesterol and triglycerides) can be monitored though regular blood test by doctors.
  • Author: Iryna Ilkavets

  • Image: Iryna Ilkavets
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