It probably does not surprise you that the major function of the adipose is to store energy as triglycerides. Compared to extrahepatic tissues as a whole, in the adipose the following pathways are not performed or are not important:
- Glycogen synthesis and breakdown
- Lactate synthesis
- Ketone body breakdown
- Fatty acid breakdown
- Protein synthesis and breakdown
- Citric acid cycle (not much since it is not an active tissue needing energy)
These pathways are crossed out in the figure below.
Figure 7.321 The metabolic pathways that are not performed or important in the adipose, compared to extrahepatic tissues as a whole are crossed out1
Removing those pathways, we are left with metabolic capabilities listed below and depicted in the following figure:
- Fatty acid synthesis
Triglyceride synthesis and breakdown
Figure 7.322 Adipose metabolic capability
Fatty acid synthesis only occurs in the adipose and liver. In the adipose, fatty acids are synthesized and most will be esterified into triglycerides to be stored. In the liver, some fatty acids will be esterified into triglycerides to be stored, but most triglycerides will be incorporated into VLDL so that they can be used or stored by other tissues.