Why are ketone bodies used exclusively as an energy source by certain extrahepatic tissues?
Disease description:
Recently, I haven't been feeling well and went to the hospital for a checkup, where I was diagnosed with a liver problem. May I ask, why is it that ketone bodies can only supply energy through oxidation to certain tissues outside the liver?
Doctor's answer (1)
Dr. Jiang Chenggang
The main reasons why ketone bodies can only be oxidized for energy supply in certain extrahepatic tissues are as follows:
1. **Presence and absence of enzymes**: The liver possesses strong enzymes for ketone body production but lacks the enzymes necessary for their utilization. Therefore, after ketone bodies are produced in the liver, they must be transported via the bloodstream to extrahepatic tissues for oxidation and use.
2. **Characteristics of ketone bodies**: Ketone bodies are intermediate products of fatty acid oxidation in the liver. Their small molecular size makes them easily oxidizable and utilizable by extrahepatic tissues. This characteristic enables ketone bodies to serve as a form of energy output from the liver to extrahepatic tissues.
3. **Physiological demand**: Under conditions of starvation or disease, when glucose supply is insufficient, vital organs such as the heart and brain switch to utilizing ketone bodies for oxidative energy production. This is a mechanism by which the organism adapts to environmental changes and maintains life activities.
