Ketogenesis

Ketogenesis is a metabolic process where the body produces ketone bodies as a result of the breakdown of fatty acids and ketogenic amino acids. This process provides energy to certain organs, especially the brain under conditions of low glucose.

Process

Ketogenesis occurs in the mitochondria of liver cells when carbohydrate intake is very low. The process begins with the breakdown of fatty acids into acetyl-CoA. Under normal conditions, acetyl-CoA is further metabolized in the citric acid cycle (also known as the Krebs cycle) to produce energy. However, when the body is in a state of fasting or starvation, or during a prolonged intense exercise, the citric acid cycle cannot process all the acetyl-CoA produced from the fatty acids.

In such conditions, the excess acetyl-CoA is converted into ketone bodies via ketogenesis. The three ketone bodies produced in the liver are acetoacetate, beta-hydroxybutyrate, and the spontaneous breakdown product of acetoacetate, acetone. These ketone bodies are then transported to other tissues, such as the brain, heart and muscle cells, where they are converted back into acetyl-CoA to produce energy.

Regulation

Ketogenesis is primarily regulated by the hormones insulin and glucagon. Insulin normally inhibits ketogenesis, while glucagon stimulates it. During periods of low carbohydrate intake, insulin levels drop, and glucagon levels rise, leading to increased ketogenesis.

Clinical significance

In conditions such as diabetes mellitus, where insulin function is impaired, ketogenesis can occur unchecked, leading to high levels of ketone bodies in the blood, a condition known as ketoacidosis. This can lead to a life-threatening condition if not treated promptly.

File:Ketogenesis pathway.svg

Ketogenesis pathway

See also

• Ketosis
• Ketogenic diet
• Ketoacidosis
• Metabolism

References

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