Glucagon and Insulin – Pancreas (Nursing)

00:00 So we also have other endocrine organs. An example of this is the pancreas. The pancreas is a triangular gland located partially behind the stomach. This is a unique organ and that it contains both exocrine and endocrine functions. The exocrine cells of the pancreas are called the acinar cells. These are going to produce enzyme-rich juice that is used for digestion. The endocrine cells are going to be found in what's known as pancreatic islets or the islets of Langerhans. These endocrine cells include alpha cells which are responsible for the production of glucagon and beta cells which are responsible for the production of insulin. As you can see, the alpha and beta cells appear like little islands among a sea of acinar cells. So the first of the pancreatic hormones that we'll discuss is glucagon. Glucagon is released by the alpha cells of the pancreas. This is an extremely potent that is triggered by decreases in our blood glucose levels, rising levels of our amino acids, or by the sympathetic nervous system. The brain in particular has an absolute requirement for glucose in order to perform its metabolic functions. So this hormone is important because it helps to maintain our blood glucose homeostasis especially during periods of fasting and starvation. Glucagon is going to raise our blood glucose levels by targeting the liver to break down glycogen into glucose also known as glycogenolysis. Also, triggering the liver to synthesize glucose from lactic acid and other non-carbohydrates in a process known as gluconeogenesis and finally to release that glucose into the blood. The other pancreatic hormone is insulin. Insulin is going to be produced by the beta cells of the pancreas. It is going to be secreted when our blood glucose levels are high and is synthesized as proinsulin that is then further modified. Insulin is going to serve to lower our blood glucose levels in 3 ways. First, it enhances the membrane transport of glucose into fat and muscle cells. It also inhibits the breakdown of glycogen to glucose by the liver. Finally, it's going to inhibit the conversion of amino acids or fats to glucose. It is not needed for glucose uptake in our liver, kidneys, or brain. And it also plays a role in neuronal development, learning, and memory. Binding to tyrosine kinase enzyme receptors also triggers cells to increase their glucose uptake. This then allows the glucose to be removed from the blood. Insulin can also trigger cells to catalyze oxidation of glucose for ATP production. This is actually the number 1 priority of insulin. It can also polymerize glucose to form glycogen, which is the way that our body stores glucose for later use. It can also trigger the conversion of glucose to fat particularly in the cells of our adipose tissue. Factors that are going to influence the release of insulin include elevated blood glucose levels; rising blood levels of amino acids and fatty acids; the release of acetylcholine by our parasympathetic nerve fibers; the hormones glucagon, epinephrine, growth hormone, thyroxine or thyroid hormone, and glucocorticoids. And also by somatostatin and sympathetic nervous system which is going to inhibit insulin release.