Regulation of blood glucose
This blood glucose level is about the lowest you can go before your brain is unable to obtain a sufficient amount of glucose.
What is 60 mg/dL (milligrams glucose per deciliter of blood)?
This process occurs mostly in liver and muscle consumes glucose after meals so it can both lower blood glucose levels as well as store glucose for later use.
What is glycogen synthesis?
This catabolic pathway that begins the process of glucose oxidation requires 10 enzymes that are present in the cytosol of all cells.
What is glycolysis?
This anabolic hormone is secreted sometimes before but definitely during and after a meal. It stimulates uptake go glucose by liver, fat and adipose as well as glycolysis and glycogenesis (glycogen synthesis).
What is insulin?
This coenzyme is responsible for accepting hydrogen atoms from carbon chains in BOTH glycolysis and the Krebs cycle. Generally, each one used by the electron transport chain results in approximately 3 ATP produced by oxidative phosphorylation.
What is NAD+?
These two numbers represent the range of normal blood glucose levels over the course of a day (including an overnight 8 hour fast).
What is 70 mg/dL (after 8 hours of fasting) and 150 mg/dL (immediately following a meal, max about 200 mg/dL)?
A process that requires information from DNA and is done by cells all the time using ribosomes but is stimulated by insulin after a meal.
What is protein synthesis?
This process occurs in the liver and muscle in the post-absorptive state, but only the liver can release its products into the blood stream in response to glucagon or epinephrine stimulation.
What is glycogenolysis (glycogen breakdown)?
This hormone is secreted by alpha cells of the Islets of Langerhans in the pancreas in the post-absorptive state. It stimulates glycogenolysis and gluconeogenesis in the liver.
What is glucagon?
This coenzyme is reduced by a reaction in the Krebs cycle, but not reduced by any reactions of glycolysis. For each reduced form of this coenzyme, approximately 2 ATP are generated by oxidative phosphorylation.
What is FAD?
This vital organ relies on a blood glucose concentration over 60 mg/dL because it exclusively uses glucose as a fuel (except during starvation when it can use ketones).
What is the brain?
A process performed mostly by adipocytes, the liver and enterocytes (the absorptive cells of the small intestine) that stores a hydrophobic form energy after a meal.
What is triglyceride synthesis?
This process occurs mostly in adipocytes (fat cells) during the post-absorptive state because that is where the majority of its substrate is stored.
What is lipolysis?
These two stress hormones secreted by the adrenal glands promote glycogenolysis, lipolysis and proteolysis in muscle, liver and fat.
What are epinephrine (adrenaline) and cortisol?
This coenzyme is made from pantothenic acid, a B vitamin. It activates intermediates of metabolic reactions, and is especially important in activating the 2-carbon acetyl group that enters the Krebs cycle.
What is coenzyme A (CoA)?
This 2-carbon substrate of the Krebs cycle can be produced by the oxidation of pyruvate, the deamination of some amino acids and the beta oxidation of fatty acids, but it can't be used to make glucose, even in times of starvation.
What is acetyl CoA (coenzyme A)?
A metabolic pathway uses chains of 3 or more carbons to produce glucose from non-carbohydrate sources. It occurs only in the liver (and the kidney during starvation) and is stimulated by glucagon.
What is gluconeogenesis?
This 3 carbon molecule is that backbone of both phospholipids and triglycerides. When it is liberated from triglycerides during lipolysis, it can be either oxidized by the enzymes of glycolysis or used to make glucose, depending on blood glucose levels.
What is glycerol?
These islands of cells in the pancreas only account for about 1% of the mass of the pancreas but they contain the cells that secrete insulin and glucagon.
What are the Islets of Langerhans?
This is the form of the coenzyme that has been reduced by either the enzymes of glycolysis OR the Krebs cycle. If it builds up too much in the cytosol, it stimulates the reduction of pyruvate to lactic acid.
What is NADH?
This cyclical metabolic pathway is central to metabolism. It can complete the oxidation of glucose, fatty acids and amino acids as well as be a source of carbon chains for amino acids. It's products include reduced NADH, FADH2 and even a little ATP (by substrate-level phosphorylation).
What is the Krebs cycle?
The hydrolysis of this RNA nucleotide (more accurately, nucleoside triphosphate) is coupled to anabolic processes to provide the energy to accomplish them.
What is ATP (adenosine triphosphate)?
This process occurs all the time in cells and produces products a variety of sizes. The larger products can be displayed on MHC complexes by cells and the smallest ones can be used to make proteins.
What is proteolysis?
This hormone is critical in maintaining blood glucose levels. Type I diabetics can't make it in sufficient quantities and Type II diabetics have receptors that are resistant to it.
What is insulin?
This reduced form of the coenzyme can't be regenerated by fermentation so if it is not delivering its hydrogen atoms to the electron transport chain, the concentration of the reduced form builds up and the oxidized form is depleted. This is why, even though the Krebs cycle does not directly use oxygen, it slows down or stops when oxygen is not available in sufficient quantities.
What is FADH2?