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Biology OCR A2-Level Revision on Blood Glucose Levels. How glucose is maintained when its too high and too low. How it leads to diabetes mellitus. The effects of glycogen and insulin on the hepatocyte cells.
Glycolysis and gluconeogenesis are two metabolic pathways that regulate the levels of glucose in the body. Glycolysis is the process by which glucose is converted into pyruvate, generating ATP in the process. Gluconeogenesis is the process by which glucose is synthesized from non-carbohydrate sources such as amino acids and fatty acids.
The regulation of these pathways is crucial for maintaining glucose homeostasis in the body. When glucose levels are too high, insulin is released by the pancreas, which stimulates the uptake of glucose by cells and the conversion of glucose to glycogen in the liver and muscle tissue. This process, known as glycogenesis, reduces the levels of glucose in the bloodstream.
Conversely, when glucose levels are too low, the pancreas releases glucagon, which stimulates the breakdown of glycogen into glucose in the liver and muscle tissue. This process, known as glycogenolysis, increases the levels of glucose in the bloodstream.
If glucose levels remain high over an extended period of time, it can lead to diabetes mellitus, a chronic metabolic disorder characterized by elevated blood glucose levels. There are two main types of diabetes mellitus: type 1 and type 2.
In type 1 diabetes, the immune system attacks and destroys the insulin-producing beta cells in the pancreas, leading to a complete lack of insulin in the body. Without insulin, glucose cannot enter cells, leading to hyperglycemia (high blood sugar levels). This can lead to a range of complications, including kidney damage, nerve damage, and vision problems.
In type 2 diabetes, the body becomes resistant to insulin, and the pancreas may not be able to produce enough insulin to meet the body's needs. This also leads to hyperglycemia and can cause similar complications as type 1 diabetes.
Glycogen and insulin play crucial roles in regulating glucose metabolism in the liver. When insulin levels are high, as in the fed state, the liver takes up glucose and converts it to glycogen through glycogenesis. Glycogen can be broken down into glucose when insulin levels are low, such as during fasting or exercise, to maintain blood glucose levels.
Gluconeogenesis also plays a role in maintaining glucose homeostasis during fasting. The liver can synthesize glucose from non-carbohydrate sources such as amino acids and fatty acids. This is important because glucose is the primary fuel source for the brain, which cannot use fatty acids for energy.
In summary, the regulation of glycolysis and gluconeogenesis is crucial for maintaining glucose homeostasis in the body. When this regulation fails, it can lead to diabetes mellitus and a range of complications. Understanding the mechanisms underlying these metabolic pathways can help us develop new treatments for diabetes and other metabolic disorders.
29 сен 2024
