During the Postabsorptive Phase of Metabolism

Question

During the postabsorptive phase of metabolism
A)glycogen in muscle cells is broken down to glucose,which is released into the blood.
B)liver glycogen is broken down to glucose,which is released into the blood.
C)triacylglycerols in adipose tissue are broken down to glucose by lipolysis.
D)the liver exports lactate to the muscles,which use it for fuel.
E)glycerol and fatty acids are rapidly assembled into triglycerides in adipose tissue.

Accepted Answer

During the postabsorptive phase, when the body is not receiving nutrients from the diet, the liver breaks down its stored glycogen and releases glucose into the bloodstream to maintain blood glucose levels. This is because glucose is a critical fuel for the brain and red blood cells, which cannot use fatty acids for energy. Muscle cells also break down their glycogen stores, but the glucose is used within the muscle itself rather than being released into the bloodstream. Lipolysis, the breakdown of stored fat, does occur during the postabsorptive phase, but the resulting fatty acids are primarily used for fuel by other tissues such as the heart and skeletal muscle rather than being converted to glucose. The liver does export lactate under certain conditions, but this is not a major source of fuel during the postabsorptive phase. Finally, fatty acids and glycerol are not assembled into triglycerides during the postabsorptive phase, but rather are broken down for fuel.