Earlier in the semester you looked at the importance of maintaining blood glucose concentrations in the blood. Why is having an adequate blood glucose concentration essential for normal function? How can tissues store glucose so that it can be made available if required?

Maintaining adequate blood glucose concentration is essential because glucose is the primary energy source that can be used by the brain. The brain can also use ketones as an energy source but they are not the preferred energy source. We often have glucose to spare and this can be stored in the body in the form of glycogen. The liver is an important site of glycogen storage. When required the glycogen can be broken down to glucose and released into the blood. Glycogen can also be stored in other tissues such as muscle. The easy way to visualise glycogen is as a network of glucose molecules that are joined to each other. As the glycogen is broken down the individual glucose molecules are liberated and can be broken down in metabolic pathways to produce ATP.