Liver blood supply

The liver is a wedge-shaped organ of some 1.5 kg in adult humans, which, in terms of blood circulation, is interposed between the gastrointestinal tract and the rest of the body. The blood supply to the liver is from the hepatic portal vein (80%) and the hepatic artery (20%), the former bringing a rich supply of nutrients direct from the intestinal tract and the latter supplying the liver with oxygen. Blood drains from the liver by the hepatic vein. The position of the liver enables it to act as a processor of the absorbed nutrients, and to control their storage... 

The number of active LDL receptors is also affected by a condition called familial hypercholesterolemia, in which there is a defective gene coding for the receptor. In either case, the reduction of active receptors means that the LDL carrying cholesterol is unable to enter the cell interior instead, it is deposited in the arteries leading to the heart or brain. These deposits build up over time and may block blood supply to the heart muscle or brain, resulting in a heart attack or stroke. In contrast, HDL transports cholesterol from other parts of the body to the liver, where it is degraded to bile acids. 

These deconjugated secondary bile acids are lipophilic and are believed to passively diffuse across the colon and enter the blood supply for return to the liver. Little is known of the mechanism, although in ASBT knockout mice there is an increase in OSTa/OSTp mRNA within the proximal colon.This could simply reflect reduced bile-acid uptake in the terminal ileum and a response to increased bile-acid levels entering the colon. 

The liver is the central organ that filters, stores, and detoxifies blood and its constituents. Thus, it is highly susceptible to a host of injuries because of its portal location and physiologic function. Blood distribution gradient exists within the liver and this heterogeneity results in differential exposure of various parts of the organ to injury. Hepatocytes closest to the portal vein and hepatic artery receive oxygen- and nutrient-rich blood supply, which makes them less susceptible to injury than those distal to blood supply [2]. 

Kann Z (1996) Dynamic study of iodized oil in the liver and blood supply to hepatic tmnors. Acta Radiol 37 Suppl 408 1... 

The liver requires cholesterol for synthesizing VLDL particles and bile acids. Triglyceride-rich VLDL particles are released into the blood and, like the chylomicrons, supply other tissues with fatty acids. Left behind are LDL particles that either return into the liver or supply extrahepatic tissues with cholesterol. 

Two amino acids—asparagine and glutamine—contain acid-amide groups in the side chains, from which NH3 can be released by hydrolysis (hydrolytic deamination). In the blood, glutamine is the most important transport molecule for amino nitrogen. Hydrolytic deamination of glutamine in the liver also supplies the urea cycle with NH3. 

Because the entire blood supply of the upper gastrointestinal tract passes through the liver before reaching the systemic circulation, a drug may be metabolized by the gut wall and the liver during its first passage of drug... 

The other program involves systemic administration of the gene-laden adenovirus via a hepatic artery catheter to treat hepatocellular carcinoma (HCC). The hepatic artery supplies the normal liver with 25% of its blood supply. However, it is the sole blood supply for the carcinoma. Preclinical results demonstrated efficacy in a rat HCC model. In a small, open-label clinical trial of patients positive for HCC, but also having post-hepatitis cirrhosis, patient response was marginal [22]. 

Herbs that strengthen the Spleen are often selected, first to provide a blood supply so as to maintain the proper function of the Liver, second to allow the Spleen to resist attack by the Liver-Qi, and third to treat Spleen-Qi deficiency. 

Scientists theorize that, due to its chemical similarity, sitostanol competes with cholesterol to be absorbed into the bloodstream from the intestine. This not only interferes with the uptake of cholesterol from the diet, but it also, more importantly, lowers the amount of cholesterol that wends its way into the blood from cholesterol synthesis in the liver. Cholesterol is an essential biochemical, which the liver can supply, but much of it accesses the bloodstream in an indirect fashion. First it s secreted through bile into the intestine, where it plays a role in fat absorption, and then it is absorbed into the blood. Sitostanol blocks this absorption. 

The blood supply ensures that the liver is exposed to relatively high concentrations of toxic substances absorbed from the gastrointestinal tract. 

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