Liver Physiology
Lara Wijayasiri, Kate McCombe, Paul Hatton, David Bogod in The Primary FRCA Structured Oral Examination Study Guide 1, 2017
Describe the blood supply to the liver. The liver is an extremely vascular organ, receiving a blood supply of 100 mL/kg/min (approximately 1800 mL/min).It has a dual blood supply, receiving approximately 70% of its blood flow from the portal vein and 30% from the hepatic artery.The portal vein is formed by the union of the splenic vein and superior mesenteric vein and thus carries blood from the gastrointestinal tract to the liver.The hepatic artery is a branch of the coeliac artery.Hepatic portal vein blood only has an oxygen saturation of approximately 70%, and so it only provides around 40% of the liver’s oxygen requirements.The hepatic artery provides approximately 60% of the liver’s oxygen requirements.Normal hepatic oxygen extraction is less than 50%. However, this can increase in response to increased oxygen demand.
The patient with acute gastrointestinal problems
Peate Ian, Dutton Helen in Acute Nursing Care, 2020
The liver is dark reddish-brown in colour and is divided into two main lobes (the larger right and the smaller left) which are further subdivided into approximately 100,000 small lobes, or lobules. About 60% of the liver is made up of liver cells called hepatocytes, which absorb nutrients and detoxify and remove harmful substances from the blood. A hepatocyte has an average lifespan of 150 days. There are approximately 202,000 hepatocytes in every milligram of liver tissue. The liver receives its blood supply via the hepatic artery and portal vein. Instead of capillaries, the liver has large endothelium lined spaces (sinusoids) through which blood passes. The sinusoids also contain fixed phagocytes called stellate reticuloendothelial (Kupffer) cells which perform several functions, including the breakdown of worn out red blood cells, bacteria and other foreign matter which can then pass into the venous circulation.
Digestive and Metabolic Actions of Dopamine
Nira Ben-Jonathan in Dopamine, 2020
The liver has multiple functions including digestion and detoxification, and it is a key regulator of metabolism via its ability to synthesize proteins and generate and store glycogen. About 70%–85% of the liver volume is occupied by parenchymal hepatocytes. Nonparenchymal cells constitute 40% of the total number of liver cells but only 6.5% of its volume. The liver has sinusoids that are lined with two types of cells—endothelial cells and phagocytic Küpffer cells—while nonparenchymal stellate cells are located in the perisinusoidal space. The liver receives a dual blood supply from the hepatic portal vein and hepatic arteries. The portal vein delivers around 75% of the liver’s blood supply and carries venous blood from the spleen, the GI tract and associated organs. The hepatic arteries supply arterial blood to the liver, accounting for the remaining 25% of its blood flow.
A fully coupled porous media and channels flow approach for simulation of blood and bile flow through the liver lobules
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
The liver, as the largest endocrine gland, has many functions and duties in the human body. Among these functions, the liver acts as a refinery producing biochemicals for digestion. One of the liver products is bile, an alkaline compound, that helps to emulsify the lipids in the digestion process. The red blood cells decomposition, glycogen storage regulation, and the hormones production are the other roles of the liver. The liver receives blood from two main vessels, including the hepatic Portal Vein (PV) and Hepatic Artery (HA), as shown in Figure 1(a). These vessels are divided into small capillaries inside the liver. Hepatic portal vein provides de-oxygenated blood, rich in digested nutrients, from the gastrointestinal tract, pancreas, and spleen. This is about 75–80% of the total volume of blood entering the liver (Garcea and Maddern 2009). The remainder is provided through the hepatic artery caring fully oxygenated blood, poor in nutrients, from the aorta to the liver (Garcea and Maddern 2009).
Preparation and evaluation of phytantriol liquid crystal as a liquid embolic agent
Published in Pharmaceutical Development and Technology, 2020
Hepatocellular carcinoma (HCC) is the third most frequent cause of cancer deaths worldwide (Forner et al. 2012, 2014), and its mortality rate is close to that of gastric and oesophageal cancers. One characteristic of HCC is that the number of new cases diagnosed each year is almost equal to the number of deaths from this cancer. In most cases, HCC is associated with chronic liver disease, which is often diagnosed at an advanced stage when treatment options lack efficacy (Galun et al. 2017). In these individuals, hepatic resection and liver transplantation are the best treatment options. However, in patients who are asymptomatic and are diagnosed with an intermediate or advanced stage of disease during physical examination, transarterial chemoembolization (TACE) is the current standard of care to relieve symptoms and prolong survival (Lencioni et al. 2013). TACE involves intra-arterial administration of chemotherapy combined with arterial embolization. Blood supply to the human liver mainly involves the hepatic artery and portal vein. Two-thirds of the blood originates from the portal vein, and the remaining one-third originates from the hepatic artery. However, the blood supply for cancerous liver tissue mainly comes from the hepatic artery. Therefore, when TACE is performed on the hepatic artery, it leads to cancerous hepatic tissue ischaemia and necrosis, while normal liver tissue is less affected. In addition, the embolic agents release anticancer drugs to the cancerous liver tissue, further inhibiting its growth and enhancing the anticancer effects (Tam et al. 2011; Qian et al. 2015).
The clinical evidence for postbiotics as microbial therapeutics
Published in Gut Microbes, 2022
Alexis Mosca, Ana Teresa Abreu Y Abreu, Kok Ann Gwee, Gianluca Ianiro, Jan Tack, Thi Viet Ha Nguyen, Colin Hill
There are areas where postbiotics have potential efficacy, for example the liver. The gut–liver axis is a bidirectional relationship between the gut, its microbiome, and the liver. The portal vein carries gut-derived products to the liver and the liver feedbacks via bile and antibody secretion into the intestine. A healthy microbiome maintains gut-liver axis homeostasis. Liver cirrhosis is associated with a profoundly altered microbiome and damaged intestinal barrier. There is increasing evidence that microorganism-derived metabolites including trimethylamine, SCFAs and ethanol have a pathogenic role in non-alcoholic fatty liver disease. Postbiotics are considered a potential new therapeutic avenue for these liver diseases, but more research is needed to confirm their benefit.100
Related Knowledge Centers
- Gastrointestinal Tract
- Pancreas
- Spleen
- Toxin
- Liver
- Blood
- Blood Vessel
- Gallbladder
- Nutrient
- Hepatic Artery Proper