Grades 6–8 · Organisms
What does the liver do with substances arriving in the blood?
Much of the blood leaving the digestive organs travels through the hepatic portal vein to the liver before returning toward the heart. This gives liver cells access to many newly absorbed substances. The liver also receives oxygenated blood through the hepatic artery.
In the diagramThe liver changes and routes many substancesGlucose can be stored as glycogenLiver cellsPortalbloodBlood outBile duct → intestineThe hepatic artery also supplies oxygenated blood.
Liver cells carry out many chemical transformations. They can store glucose as glycogen and later help release glucose to the blood. They also handle amino acids. Nitrogen removed during amino-acid processing can form ammonia, which the liver converts into urea. Urea then travels in blood to the kidneys for removal in urine.
The liver also makes bile. Bile travels through ducts toward the intestine, with the gallbladder providing storage along the route. Bile helps disperse fats and carries substances such as processed bilirubin, a breakdown product associated with old red blood cells. Blood and bile therefore use separate pathways.
The liver changes many medicines and other chemicals, but it is not a magical filter that makes every substance harmless. Some products leave in blood, some are stored and others enter bile. The diagram shows these different destinations as parts of a chemical processing organ.
About this explanation
Starting knowledge: Know blood carries dissolved substances and the intestine absorbs nutrients.
Sources
- OpenStax, Anatomy and Physiology 2e — Circulatory Pathways
- OpenStax, Anatomy and Physiology 2e — Accessory Organs in Digestion: The Liver, Pancreas, and Gallbladder
- OpenStax, Anatomy and Physiology 2e — Protein Metabolism