100 7.31 Muscle Macronutrient Metabolism

Compared to extrahepatic tissues as a whole, in the muscle the following pathways are not performed or are not important:

Fatty acid synthesis

Ketone body breakdown

These pathways are crossed out in the figure below.

Removing those pathways, the following metabolic pathways make up the muscle metabolic capability:

Glycogen synthesis and breakdown

Glycolysis

Protein synthesis and breakdown

Triglyceride synthesis and breakdown

Fatty acid breakdown

Lactate synthesis

Muscle is a major extrahepatic metabolic tissue. It is the only extrahepatic tissue with significant glycogen stores. However, unlike the liver, the muscle cannot secrete glucose after it is taken up (no glucose-6-phosphatase). Thus, you can think of the muscle as being selfish with glucose. It either uses it for itself initially or stores it for its later use.

References & Links

1. http://en.wikipedia.org/wiki/File:CellRespiration.svg