Glycogen is predominantly found in which tissues?

• A. brain and liver
• B. skeletal muscle and kidneys
• C. small intestine and brain
• D. liver and skeletal muscle

Answer: (D)

Glycogen is the body's rapid-release storage form of glucose, kept mainly in two tissues because they serve different but complementary roles in energy management. The liver stores glycogen to maintain blood glucose levels between meals, supplying glucose to the bloodstream as needed to support brain and other tissues. Skeletal muscle stores glycogen to fuel its own contractions during activity, using the glucose locally rather than exporting it to the blood. The brain requires relatively constant glucose but contains little stored glycogen, and kidneys and the small intestine do not serve as major glycogen reservoirs. Therefore, the tissues where glycogen predominates are liver and skeletal muscle.