Dan22

This is a clear, step-by-step guide to understanding how your body breaks down, stores, and uses carbohydrates for energy. From digestion and glucose transport to glycolysis, gluconeogenesis, glycogen metabolism, and hormonal control (insulin and glucagon), this learning resource turns complex pathways into an organ

Glycogen role (storage of glucose) — Comprises glucose units stored as glycogen (mainly in liver and muscle) to buffer energy and maintain blood glucose. Glycogen synthase vs glycogen phosphorylase (opposing functions) — Liver/muscle balance glycogenesis (build) vs glycogenolysis (breakdown) to match nutrient and energy status. Liver glycogen: blood glucose support — In hepatocytes, glycogenolysis helps maintain systemic glucose availability between meals. Muscle glycogen: local fuel fo...

Gluconeogenesis (overview): Synthesis of glucose (primarily from non-carbohydrate sources) to maintain blood glucose during fasting. Primary site (liver & kidneys): Mainly occurs in liver and kidneys, with contributions from other tissues such as GI epithelium. Fasting function: Ensures continued glucose availability when dietary carbohydrate is limited. Glucogenic substrates (overview): Uses glucogenic amino acids, lactate, pyruvate, and glycerol as carbon sources. Pathway direction opposit...

TCA cycle (overview): Mitochondrial oxidation of acetyl-CoA to CO₂, generating energy carriers for oxidative metabolism. Mitochondrial location: Occurs in the mitochondria, coupling carbohydrate oxidation to the ETC. Acetyl-CoA entry: The pathway is fed by acetyl-CoA produced from earlier steps (e.g., pyruvate breakdown). CO₂ release: Progressive decarboxylation drives carbon loss as CO₂ and maintains thermodynamic direction. Energy capture (NADH/FADH₂): Produces reduced cofactors th...

Glycolysis (overview): Cytosolic breakdown of glucose to pyruvate, functioning under both aerobic and anaerobic conditions. Cytosolic location: Main reactions occur in the cytosol, separating glycolysis from mitochondrial steps. Two phases (preparatory & payoff): Glycolysis is organized into an energy-investment phase followed by an energy-yielding phase. Aerobic vs anaerobic operation: Pyruvate handling differs depending on oxygen availability, while glycolysis itself remains central. Energ...

Lecture1: covers the fundamentals of carbohydrate digestion, absorption, and initial metabolic fates. It describes how dietary carbohydrates (plant starch/cellulose, animal glycogen, and disaccharides sucrose/lactose) are hydrolyzed by salivary and pancreatic α-amylase in the mouth and small intestine, followed by brush-border disaccharidase activity to generate glucose, galactose, and fructose. It also explains mono-sugar uptake mechanisms across intestinal epithelial cells, including Na⁺...