Tissue‐specific differences in metabolism

Glucose in the liver can be stored as glycogen or they can also be converted into triglycerides (in order to store fat). In order to convert glucose to fatty acids it has to go through pyruvate and Acetyl-CoA to form the Palmitate, a fatty acid synthesizable by us. Glycerol and fatty acids can be combined to form triglycerides. In the liver, we do not store Triglycerides rather we store them mostly in adipose tissue. Triglycerides cannot be transported in the blood. As a result, they have to be converted into VLDLs (Very low-density lipoproteins). We can then export VLDL out of the liver into the blood. Amino acids taken by the liver will be broken down into Keto Acids. These alpha-keto acids give off ammonia (eventually becomes urea and it is excreted as waste). Keto acids can be converted to fatty acids and then triglycerides to be stored in adipose tissue. Keto acids can be broken down into Acetyl-CoA, go through the Krebs cycle, the ETC and then produce ATP for energy. Glucose in adipose tissue is converted to glycerol and fatty acids and then going to be broken down into triglycerides (The storage form of our fats). Fatty acids can be combined with glycerol to form fatty acids as well. In our muscles, glucose can be stored as glycogen, or it can also be converted into pyruvate and as we know through cellular respiration, we have the ability to create ATP, giving our muscles usable energy. Muscles can also take up amino acids from proteins we eat in the absorptive state. These amino acids can be stored as protein in our muscle. As recently discussed, during the absorptive state we can store energy as glycogen, triglycerides as well as protein, but the brain is a bit of a different scenario. Glucose in the brain is converted to pyruvate, and it goes through cellular respiration to produce ATP for the brain to work. It is also good to note that in the post absorvative state keto acids in the liver are going to be used directly to create glucose. Allowing that glucose to be exported to other parts of the body. Some of these keto acids are still going to be broken down into Acetyl-CoA to produce ATP. Glycerol fatty acids can also be converted into glucose in the post-absorvative state. These fatty acids can also be broken down to form Ketones. Ketones are one of the very few types of energy that can be used by the brain. For the post absorvative state in Adipose tissue, glycerol and fatty acids can just be exported into the blood, and travel to the liver in order to make more glucose. The proteins in our muscles can also be broken down into amino acids and through the bloodstream reach the liver where they can be converted to alpha keto acids and then converted into glucose for energy. In the post absorvative state, we can convert glycogen in our muscles to glucose and then it can be converted into pyruvate, which will then continue to make Acetyl-CoA and create energy through the ETC. Glucose in our muscles can also be broken down into lactate to produce ATP without the necessity of oxygen. Cellular respiration is more efficient and will produce more ATPs in comparison to breaking glucose down into lactate. Lactate is an acid and it can destabilize the pH levels in our blood.