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The Liver

Human Biology (Year 12) - Maintaining Glucose Balance

Ben Whitten

What is the role of the liver?

The liver is located in the upper part of the abdominal cavity, just below the diaphragm. It is the largest endocrine gland in the body and plays a key role in the control of blood glucose concentration.

The liver can convert glucose into glycogen for storage (in a process called glycogenesis). This process is stimulated by the pancreatic hormone insulin, and glycogen cannot be used by cells itself;  it must be converted back into glucose or to other simple sugars. The liver can also convert glycogen into glucose for release into the blood (in a process called glycogenolysis) to be used by body cells.

The hepatic portal vein is where most of the liver's blood supply travels through. The hepatic portal vein brings blood directly from the stomach, spleen, pancreas, and large and small intestines. This means that the liver is the first gland which can absorb the nutrients from digested food. The breakdown products of a meal with a high level of carbohydrates are mainly glucose, which are absorbed into the blood capillaries of the villi of the small intestine (small, hair-like projections which act to increase the surface area of the small intestine).

The hepatic portal vein carries the glucose to the liver, where a number of different key processes can occur. This includes:

  • Glucose being removed from the blood by the liver in order for energy to be provided for normal liver function

  • Glucose being removed by the liver and/or the muscles and undergo glycogenesis for storage

  • Glucose remaining in the blood to be readily available for body cells to absorb and use it as a source of energy

  • Glucose being converted into fat (in a process called lipogenesis) for long-term storage to maintain normal blood sugar levels and tissue glycogen levels

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