2. Plasma glucose is the primary physiological regulator of insulin and glucagon secretion, but amino acids, fatty acids, and some GI hormones also play a role.
3. Insulin has anabolic effects on carbohydrate, lipid, and protein metabolism in its target tissues, where it promotes the storage of nutrients.
4. Effects of glucagon on carbohydrate, lipid, and protein metabolism occur primarily in the liver and are catabolic in nature.
5. Type 1 diabetes mellitus results from the destruction of beta cells, whereas type 2 diabetes often results from a lack of responsiveness to circulating insulin.
6. Diabetes mellitus may produce both acute complications, such as ketoacidosis, and chronic secondary complications, such as peripheral vascular disease, neuropathy, and nephropathy.
The development of mechanisms for the storage of large amounts of metabolic fuel was an important adaptation in the evolution of complex organisms. The processes involved in the digestion, storage, and use of fuels require a high degree of regulation and coordination. The pancreas, which plays a vital role in these processes, consists of two functionally different groups of cells.
Cells of the exocrine pancreas produce and secrete digestive enzymes and fluids into the upper part of the small intestine. The endocrine pancreas, an anatomically small portion of the pancreas (1 to 2% of the total mass), produces hormones involved in regulating fuel storage and use.
For convenience, functions of the exocrine and endocrine portions of the pancreas are usually discussed separately. While this chapter focuses primarily on hormones of the endocrine pancreas, the overall function of the pancreas is to coordinate and direct a wide variety of processes related to the digestion, uptake, and use of metabolic fuels.
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