This section will give us a look at the importance of maintaining blood glucose levels in the body and how this is regulated. You will learn about the processes and hormones involved in changing glucose concentrations in the blood. You will gain an understanding of the difference between insulin and glucagon and how and when they work to modify blood glucose levels to maintain homeostasis. Furthermore, you will learn how glucose is synthesized by various enzymes through gluconeogenesis and how glucose is broken down through the process of glycolysis. We will as well explore the role of the pancreas in generating and secreting hormones necessary for glucose regulation. Several real-world examples will be given to further your understanding.
Glucose is a simple sugar that is required for energy (ATP) production throughout the body. Due to the central importance of glucose as a source of energy in the body, blood glucose concentrations are constantly monitored and regulated through physiological mechanisms. [1] The pancreas, a glandular organ in the abdomen, is the main source of hormones that are used to regulate blood glucose. These hormones, including insulin and glucagon, maintain blood glucose concentrations within a narrow range between 4 and 5 mmol/L. Even a slight decrease in blood glucose levels, to less than 2-3 mmol/L, can cause dizziness, confusion, seizures, coma and even death. These symptoms occur because glucose is the primary fuel source used by the brain. In desperate circumstances the brain can utilize ketone bodies that are derived from fat, yet this is not ideal. In states of hypoglycemia the brain limits its glucose utilize, shutting off all functions not required for survival which causes impaired cognitive functioning. In extreme and prolonged states of hypoglycemia the brain starves, leading to cerebral damage and possibly death. [2] The body is better at tolerating elevated blood glucose levels but runs into problems when concentrations rise above 30-40 mmol/L. When blood glucose concentrations are high, excess glucose is removed from the body at the level of the kidney. The kidney is incredibly valuable at removing excess glucose from the blood, nevertheless water follows the glucose by osmotic draw and is as well excreted from the body. This leads to osmotic diuresis, or increased urine production, and can lead to severe dehydration. [3] Ideally, any excess glucose is stored within the muscle and liver as glycogen and within the adipose tissue as triglycerides. Once glucose is absorbed into skeletal muscle cells or adipocytes it is trapped and must be used by that cell. Only the liver is capable of releasing glucose back into circulation. Skeletal muscle and adipose tissue can indirectly liberate glucose by releasing molecules such as amino acids and lipid byproducts into the blood. These molecules can then be taken up and used by the liver to produce new glucose molecules that can be released in circulation.
This particular example perfectly highlights why Beta-Cell Moderates Glucose is so captivating.
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