There are numerous hormones synthesized within the human body, insulin is one of the most critical components. Although it is primarily associated with diabetes, wherein people with high blood sugar take it as a synthetic medicine, insulin is fundamentally a key biological hormone essential for carrying out several important tasks in the human system. These consist of proper glucose uptake by cells, regulating energy metabolism, preserving genetic operations and DNA replication in cells, promoting the production of fat and protein, besides enhancing digestive functions and stimulating blood circulation.
Insulin And Its Structure:
Insulin is a peptide hormone, composed of long chains of proteins and amino acids, that performs numerous crucial functions in the human system, being chiefly involved in glucose metabolism. It was the first peptide hormone to be discovered in the year 1921 by three renowned medical researchers – Canadian physician Sir Frederick Grant Banting, American-Canadian scientist Charles Herbert Best and Scottish biochemist J.J.R. Macleod.
Later on, in the year 1951, famed British biochemist Frederick Sanger determined the precise amino acid arrangement of insulin, with another prominent British chemist Dorothy Hodgkin decoding its elaborate chemical crystal structure. The human insulin protein is made up of 51 amino acids, with a molecular mass of 5808 Da (the unified atomic mass unit known as the dalton). It occurs in the form of a heterodimer i.e. a protein composed of two chains – A-chain and B-chain joined by disulfide bonds.
Functions Of Insulin:
Insulin is first and foremost a biological hormone, necessary for optimal energy metabolism and ensuring a long, healthy life. Hormones are chemical substances synthesized by specialized cells present within a gland, which relay vital information to other tissues and organs in the body. In this regard, the insulin hormone is produced by beta cells in the pancreas, an organ situated in the abdominal tract, posterior to the stomach, which operates as a gland.
The central function of insulin is permitting cells to assimilate glucose from blood circulation for energy supply in biochemical reactions. The insulin hormone works alongside glucagon, another important hormone secreted by the alpha cells in the pancreas, to ensure normal glucose metabolism occurs in the body. When blood glucose levels are high, the pancreatic beta cells promptly make insulin and release it into the bloodstream, to facilitate the uptake of glucose by cells for their biochemical energy needs. Hence, insulin increases glucose uptake by cells and lowers blood sugar levels. Glucagon functions in the exact opposite manner. When blood glucose levels become low, then the pancreatic alpha cells synthesize glucagon and let it flow out into the blood, which then impacts the liver to convert glycogen stores into glucose, along with its release and raises blood sugar levels. In this manner, glucose homeostasis or a balance in the concentrations of sugars in the blood is achieved.
Apart from regulating blood glucose levels and aiding in energy metabolism, insulin is also involved in splitting up complex lipid and protein molecules into simpler substances to ease digestion. Moreover, it plays a significant role in carbohydrate metabolism, increases the synthesis of fats and proteins, augments heart functions and preserves cardiac muscle activity, elevates hydrochloric acid secretions in the stomach in response to food intake, for smooth digestion. Insulin also ensures genetic tasks of DNA replication, assimilation of amino acids by cells, bolstering the action of various biochemical enzymes and maintaining electrolyte balance by controlling levels of sodium and potassium ions.
Insulin Blood Test:
A simple blood test, in which the tissue fluid is extracted from a person via injections, helps to measure the amounts of insulin circulating in the system. In a normal, healthy individual, insulin levels in blood between consumption of meals are in the range of 8 – 11 uIU/mL.
However, for the purpose of gauging the effective action on insulin in the body, blood glucose levels are calculated at various phases. In the A1C test, blood glucose is quantified over a period of two to three months, wherein an A1C reading below 5.7 is normal and healthy.
Fasting glucose tests and post-prandial glucose tests at 2 hours following consuming meals also help determine if insulin hormone functions are normal within the system. While fasting glucose of less than 100 mg/dL is normal, post-prandial glucose concentrations of below 140 mg/dL indicate good health.
Adverse Effects Of Hormonal Imbalance Of Insulin:
When the functioning of insulin fails due to autoimmune conditions, structural defects then glucose levels in the blood rise above normal, causing hyperglycemia and eventually leading to type 2 diabetes mellitus.
When damage to the pancreatic beta cells results in a lack of production of adequate quantities of insulin or no insulin secretion altogether, then the condition is termed as type 1 diabetes mellitus.
There exists yet another illness, wherein insulin production and structure are both normal, but the cells do not respond to insulin hormone signals and hence fail to absorb glucose from the blood. This is termed as insulin resistance.In type 1 and type 2 diabetes, hormone-regulating medicines and synthetic insulin injections are prescribed and administered by the doctor, to rectify insulin synthesis defects and regulate glucose metabolism in the body.