Introduction
Among the hormones of the pancreas are the following:
- Insulin
- Glucagon
- Somatostatin (SIH)
Education
Education: The hormones of the pancreas are produced in the so-called Langerhans cells, whereby three different types are known: In the alpha cells the hormone glucagon is produced, in the beta cells insulin and in the delta cells somatostatin (SIH), whereby these three different hormones influence each other in their production and release. The beta cells make up about 80%, the alpha cells 15% and the delta cells the rest. The hormone insulin as pancreatic hormone is a protein (peptide) consisting of a total of 51 amino acids, which are divided into an A and a B chain.
Insulin is produced from a precursor protein, pro-insulin, after a protein residue (C chain) has been split off. The receptor of this hormone consists of four subunits (heterotetramer) and is located on the cell surface. – alpha-,
- Beta and
- Delta cells.
Regulation
The hormones of the pancreas are mainly regulated by blood sugar and dietary protein. Fatty acid levels play a lesser role in the secretion of hormones. A high blood sugar level promotes insulin secretion, while a lower level promotes glucagon release.
Both hormones are also stimulated by breakdown products of dietary protein (amino acids) and the autonomic nervous system. The sympathetic nervous system promotes glucagon release via norepinephrine, while the parasympathetic nervous system promotes insulin release via acetylcholine. Free fatty acids from body fat inhibit glucagon secretion but promote insulin release.
In addition, insulin release is influenced by other hormones of the gastrointestinal tract (e.g. secretin, GLP, GIP), in that these hormones make beta cells more sensitive to glucose and thus increase insulin secretion. Inhibitory hormones also exist, such as amylin or pancreatostatin. There are also other substances that regulate the glucagon level and promote the release of glucagon (gastrointestinal tract hormones) or inhibit its release (GABA).
The hormone somatostatin is released when there is an increased supply of sugar, protein and fatty acids and inhibits the release of both insulin and glucagon. Furthermore, other hormones force the release of this hormone (VIP, secretin, cholecytokinin, etc. ).
Function
The hormones of the pancreas mainly affect the carbohydrate metabolism (sugar). Furthermore, they participate in the regulation of protein and fat metabolism and other physical processes.
Effect of insulin
The hormone insulin lowers blood sugar levels by absorbing glucose from the blood into the cells (especially muscle and fat cells), where the sugar is broken down (glycolysis). The hormone also promotes sugar storage in the liver (glycogenesis). In addition, insulin has an anabolic effect, i.e. it generally “builds up” the body’s metabolism and stimulates the storage of energy substrates.
For example, it promotes the formation of fats (lipogenesis) and thus has a lipogenic effect and increases the storage of protein, especially in the muscles. Furthermore, insulin serves to support growth (longitudinal growth, cell division) and has an influence on the potassium balance (potassium uptake into the cell by insulin). The last effect is the increase of the heart strength by the hormone.
Generally speaking, in simple terms, glucagon is the “antagonist” of insulin by raising the blood sugar level. It can be used therapeutically in cases of severe, life-threatening hypoglycaemia. Glucagon is often referred to in the vernacular as the “hunger hormone”.
Production and release The peptide hormone is produced by the A-cells of the islets of Langerhans in the pancreas and consists of 29 amino acids. Glucagon is released into the bloodstream when the blood sugar level drops, but also when the amino acid concentration increases and the free fatty acids decrease. Some hormones of the digestive system also promote the release of glucagon.
Somatostatin, on the other hand, inhibits secretion. Effects Glucagon initially aims at mobilizing the energy reserves of our body. It promotes the breakdown of fat (lipolysis), protein breakdown, glycogen breakdown (glycogenolysis), especially in the liver, and the extraction of sugar from amino acids.
As a whole, the blood sugar level can be raised. Furthermore, ketone bodies are produced in increased quantities, which can be used as an alternative source of energy, e.g. for our nervous system, in case of hypoglycaemia. Glucagon deficiency If the pancreas is damaged, a lack of glucagon can occur.
However, it is more likely to be a simultaneous insulin deficiency. This is because an isolated glucagon deficiency does not normally lead to profound disorders, as the body can easily compensate for this condition by, for example, reduced insulin secretion. Excess glucangon In very rare cases, an A-cell tumour of the Langerhans cell islets can be responsible for an excessive glucagon level in the blood.
General insulin is the central metabolic hormone in our body. It regulates the absorption of sugar (glucose) into the body’s cells and also plays an important role in diabetes mellitus, also known as “diabetes” in the vernacular. Formation and synthesis In the B cells of the islets of Langerhans in the pancreas, the 51 amino acids long peptide hormone insulin, consisting of an A and B chain, is produced.
During synthesis, insulin passes through inactive precursors (preproinsulin, proinsulin). Thus, the C-peptide is split off from proinsulin, which nowadays is of considerable importance in the diagnosis of diabetes. Release Rising blood sugar levels are the most important trigger for the release of insulin.
Certain hormones from the gastrointestinal tract, such as gastrin, also have a stimulating effect on insulin secretion. Effects First and foremost, insulin stimulates our cells (especially muscle and fat cells) to absorb energy-rich glucose from the blood, thus causing a reduction in blood sugar levels. Furthermore, it promotes the creation of energy reserves: glycogen, the storage form of glucose, is increasingly stored in liver and muscle (glycogen synthesis).
In addition, potassium and amino acids are absorbed faster in muscle and fat cells. Diabetes mellitus and insulin Insulin and diabetes mellitus are closely linked in many ways! In both type 1 and type 2 diabetes, a deficiency of this important hormone is the main cause.
While type 1 is characterised by destruction of the insulin-producing islets of Langerhans, type 2 is characterised by a reduced sensitivity of the body cells to insulin. In recent years, the frequency of type 2 diabetes has increased significantly. It is estimated that one in 13 people in Germany now suffers from the disease.
Overweight, high-fat nutrition and lack of exercise play a major role in its development. Nowadays, human insulin can be produced artificially and used for the therapy of diabetes mellitus. In this way, the vital lowering of the blood sugar level and the energy supply of the cells can be guaranteed.
For this purpose, patients inject the hormone under the skin with a small needle (“insulin pen”, “insulin pen”). Somatostatin is the “inhibitor” of our hormone system. In addition to inhibiting the release of numerous hormones (e.g. insulin), experts suspect a role as a messenger substance (transmitter) in the brain.
In particular, the hormone suffers from its effect as an opponent of the growth hormone somatotropin. Somatostatin is produced by many cells in our body. The D cells of the pancreas, specialized cells of the stomach and small intestine, as well as cells of the hypothalamus produce somatostatin.
With 14 amino acids it is a very small peptide. Similar to insulin secretion, high blood sugar levels in the blood play a major role. But also a high concentration of protons (H+) in the stomach, as well as increasing concentrations of the digestive hormone gastrin, promote the release.
Finally, somatostatin can be seen as a kind of “universal brake” on the hormone system. It inhibits digestive hormones, thyroid hormones, glucocorticoids and growth hormones. Somatostatin also reduces the production of gastric juice and pancreatic enzymes.
It also inhibits gastric emptying and thus reduces digestive activity. – Insulin
- Glucagon
- TSH
- Cortisol
- Somatotropin
- Gastrin. Artificially produced somatostatin, called octreotide, can be used in modern medicine to treat some diseases. Octreotide can be used to treat acromegaly, the huge growth of the nose, ears, chin, hands and feet.