Effects of Hormones on Glycolysis

Where are insulin and glucagon produced, and what controls their secretion into the blood  

Insulin and glucagon are polypeptide hormones synthesized in, and secreted by, the pancreas. Insulin is produced by the / cells of the pancreas, and glucagon by the a cells. The secretion of either of these hormones depends on the blood glucose concentration above 4.5-5.5 mM (80-100 mg/100 mL) of glucose, insulin is secreted, but below 4.5 mA/ (80 mg/100 mL). glucagon is secreted. 

The action of glucagon and epinephrine in the stimulation of glycogen degradation in their target tissues is mediated by a process involving cyclic AMP (Chap. 6). 

Cyclic AMP, or cAMP for short, is produced by he intramolecular eyclization of ATP, a reaction catalyzed by the enzyme adenylate (or adenyl) cyclase. 

Being hormones derived from many amino acids (glucagon) or from a single amino acid (epinephrine), these compounds cannot enter their target cells directly. Consequently, liver cells have separate 

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