A healthy subject who fasts for 24 hours is most likely to have a decrease in which of the following?

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Quizplus · Accepted Answer

During a 24-hour fast, hepatic glycogenesis decreases as glycogen stores are depleted and the liver shifts to glycogenolysis and gluconeogenesis to maintain blood glucose levels.  During periods of fasting, the pancreas releases glucagon to stimulate the liver to deliver glucose to the blood. When glucagon binds to its receptors on hepatocytes, there is activation of adenylate cyclase resulting in increased cAMP with consequent activation of PKA. PKA phosphorylates and activates glycogen synthase-phosphorylase kinase, which will phosphorylate and activate phosphorylase while also phosphorylating and inhibiting glycogen synthase. The increased activity of phosphorylase results in increased release of glucose from glycogen while the inhibited glycogen synthase reduces glycogenesis.

A Healthy Subject Who Fasts for 24 Hours Is Most