Ketone Bodies

Ketone bodies are produced in the liver and utilized by extrahepatic tissue. Excess production occurs primarily due to unavailability of carbohydrates to the tissues. Ketone bodies are three in number:

·        Acetoacetate

·        β-hydroxybutyrate

·        Acetone

Fate of ketone bodies:

·        Utilized as energy substrates by the extrahepatic tissues

·        Excreted in urine

·        Expired out in breath

Utilization of ketine bodies:

·        Ketone bodies are needed to provide energy to the peripheral tissues during starvation.

·        Brain can use ketone bodies as fuel

·        Liver cannot itself use ketone bodies as fuel because it cannot reconvert acetoacetate to acetoacetyl CoA due to lacking of enzyme succinyl CoA: acetoacetyl CoA transferase.

Erythrocytes cannot utilizes ketone bodies due to absence of mitochondria.

Discuss the role of fatty acid and ketone bodies as a source of energy

Ketone bodies as asource of energy:

·        Ketone bodies are needed to provide energy to the peripheral tissues during starvation.

·        Brain can use ketone bodies as fuel.

·        Liver cannot use ketone bodies as fuel

·        Erythrocyte cannot use ketone bodies due to absence of mitochondria.

Fatty acid are important source of energy because they are both reduced and anhydrous. The energy yield from a gram of fatty acid is approximately 9K.cal compared to 4K.cal/gm for carbohydrate. Since the hydrocarbon portion of fatty acids is hydrophobic, these molecules can be stored in a relatively anhydrous environment.