In conditions of glucose deprivation, such as fasting or carbohydrate restriction, ketogenesis serves to reduce our needs for glucose. This reduces the need to engage in the energetically wasteful process of gluconeogenesis, which would otherwise be extremely taxing on our skeletal muscle if dietary protein were inadequate. Ketogenesis mainly occurs in the liver. The biochemical …
The last lesson covered how insulin, glucagon, and allosteric regulators from within the liver ensure that the liver only engages in gluconeogenesis when it can and when it needs to. This lesson focuses on an additional layer of regulation: cortisol. Cortisol is the principal glucocorticoid in humans. Glucocorticoids are steroid hormones produced by the adrenal …
Since gluconeogenesis is extremely expensive, it has to be tightly regulated so that it only occurs when both of two conditions are met: 1) the liver has enough energy to invest a portion into synthesizing glucose, and 2) the rest of the body is in need of that glucose. Since the liver is the metabolic …
Gluconeogenesis is extremely expensive. Three steps of glycolysis are so energetically favorable that they are irreversible. Getting around them requires four gluconeogenesis-specific enzymes and the investment of a much larger amount of energy. Overall, six ATP worth of energy are invested to yield glucose, a molecule that only yields 2 ATP when broken down in …
Insulin is commonly seen as a response to blood glucose whose primary role is to keep blood glucose within a narrow range. This view of insulin fails to account for its many roles outside of energy metabolism that govern long-term investments in health. The biochemistry and physiology of insulin secretion suggest, rather, that insulin is …
The pentose phosphate pathway provides a deep look into a stunning array of essential roles for glucose. In it, glucose becomes the source of NADPH, used for antioxidant defense, detoxification, recycling of nutrients like vitamin K and folate, and the anabolic synthesis of fatty acids, cholesterol, neurotransmitters, and nucleotides. At the same time, glucose also …