Insulin secretion or insulin secretion is the release of the vital hormone insulin by the pancreas.
What is insulin secretion?
Insulin secretion or insulin secretion is the release of the vital hormone insulin by the pancreas (pancreas). Insulin is produced exclusively in the beta cells of the islets of Langerhans located in the pancreas, from which its name is derived. Insulin secretion is stimulated by increased glucose, and to a lesser extent by free fatty acids and some amino acids, as well as by gastrointestinal hormones. Triggers increase the production of adenosine triphosphate (ATP) in beta cells, leading to blockade of potassium-dependent channels. This allows calcium ions from the extracellular space to better enter the beta cells and activate insulin secretion. Insulin vesicles then fuse with the cell membrane of the beta cell and empty into the extracellular space (process of exocytosis). Insulin secretion begins. Insulin release is not steady, but intermittent. Approximately every 3 to 6 minutes, beta cells release insulin into the blood.
Function and purpose
Insulin ensures that the body’s cells absorb glucose from the blood for energy conversion. In this function as a link between sugar and cell, insulin ensures that blood glucose levels remain within the normal range and do not increase. It is the only hormone capable of lowering blood glucose levels. Its counterpart glucagon, as well as cortisol, adrenaline and the thyroid hormones in moderation, on the other hand, cause the sugar level in the blood to rise. When the body ingests carbohydrate-rich food, it converts it into sugar, which causes blood sugar levels to rise. In response, the beta cells secrete more insulin. This helps the glucose from the blood to pass through the cell walls into the cell interior, whereupon the glucose content in the blood plasma decreases. In the body’s cells, the glucose is then either stored as glycogen or immediately converted into energy. The glycogen is stored inside the cell until there is an acute need for energy. Then the body draws on the glycogen stores and converts them into the required energy. The central step of this conversion, known as glycolysis, takes place in ten individual steps. During this process, the glucose is broken down into lactic acid and ethanol with the help of the nucleotide adenosine triphosphate and prepared for further energy conversion. Liver and muscle cells in particular can absorb and store large amounts of glucose. They respond particularly well to the effect of insulin in that, with increased insulin delivery, their cell membranes become more permeable and more accessible to glucose. In contrast, neurons take up glucose from the blood independently of insulin release. If insulin-dependent cells take up more glucose when insulin levels are elevated, a glucose insufficiency may develop in nerve cells, because in this case too little glucose remains for them. In severe hypoglycemia (low blood glucose), there is therefore a risk of damage to the glucose-dependent nervous system. If the blood glucose level falls below a value of about 80 mg/dl, the aforementioned antagonists adrenaline, glucagon or cortisol come into play to counteract the rise in blood glucose. Meanwhile, the body’s insulin production is greatly reduced.
Diseases and medical conditions
Diabetes mellitus is the generic term for various disorders in the body’s use of insulin. In type 1 diabetes, the body is no longer able to produce the insulin itself. In this case, the immune system destroys the insulin-producing beta cells, eventually leading to an insulin deficiency. As a result, the glucose in the blood can no longer reach the cells and they lack an energy source. As a result, after a certain period of time, there is a lack of energy in the body’s cells, a rise in blood sugar, loss of nutrients and water, and acidification of the blood. Type 1 diabetes is usually treated with artificially produced insulin preparations, which are administered subcutaneously in the form of injections or with the aid of an insulin pump. The exact cause of type 1 diabetes has not yet been clarified.It is now assumed to be a multifactorial process in which both genetic and environmental influences are involved. In type 2 diabetes, the body can still produce insulin itself, but its effect is limited due to insulin resistance in the cells. Type 2 diabetes often develops over a long period of time. Several years can pass before absolute insulin resistance and the actual diagnosis of type 2 diabetes. In the beginning, the body can compensate for the reduced processing of insulin in the cells by increasing insulin production. However, the longer the disorder persists, the worse the pancreas gets at keeping up with production and blood glucose can no longer be regulated. Eventually, type 2 diabetes is manifested. Type 2 diabetes is also thought to have multifactorial causes. Unlike type 1, however, obesity is at the top of the list of possible triggers. A freshly manifested type 2 diabetes is therefore often initially treated with a diet. However, genetic factors can also be the cause of type 2. In this case, or if type 2 diabetes still exists after weight loss, it is treated with tablets. Another, but much rarer, disease related to insulin is so-called hyperinsulinism. In this case, too much insulin is produced by an overproduction of the beta cells. Frequent hypoglycemia (low blood sugar) is the result.
