Category: Lab Notes: Physiology

Physiology is the branch of biology that studies how living organisms and their parts function. Explore cellular, molecular, human, animal, plant, comparative, exercise, environmental, and clinical physiology, along with homeostasis, regulation, adaptation, and physiological processes.

Glycogen metabolism is the coordinated process through which glucose is stored as glycogen and released when energy or glucose is required. Glycogenesis produces glycogen during periods of nutrient availability, while glycogenolysis mobilizes stored glucose during fasting, exercise, and increased energy demand. The liver uses glycogen mainly to support blood glucose homeostasis, whereas skeletal muscle glycogen provides fuel for muscle activity. Insulin, glucagon, epinephrine, cellular energy status, and metabolic signaling pathways regulate these processes.

Energy metabolism allows cells to convert carbohydrates, fats, and proteins into usable energy. Explore ATP production, glycolysis, the citric acid cycle, oxidative phosphorylation, fatty acid oxidation, glycogen metabolism, amino acid metabolism, mitochondria, insulin signaling, AMPK, and metabolic flexibility.

Hyperinsulinemia is a condition characterized by elevated circulating insulin levels. It commonly develops as a compensatory response to insulin resistance, allowing the pancreas to produce more insulin to maintain glucose homeostasis. Understanding hyperinsulinemia provides insight into insulin signaling, glucose and lipid metabolism, obesity, metabolic syndrome, prediabetes, and type 2 diabetes.

Glucose metabolism is a central component of human energy metabolism that controls how glucose is absorbed, transported, used, stored, and produced. It includes glycolysis, glycogen synthesis and breakdown, gluconeogenesis, the pentose phosphate pathway, and mitochondrial oxidation. These pathways are regulated by insulin, glucagon, nutrient availability, exercise, and energy status and are closely connected with insulin sensitivity, insulin resistance, metabolic syndrome, and diabetes.

Muscle metabolism determines how skeletal muscle produces, stores, and uses energy during rest and exercise. Explore ATP production, muscle glycogen, glycolysis, fatty acid oxidation, mitochondrial metabolism, amino acid metabolism, insulin signaling, AMPK, muscle protein synthesis, and metabolic flexibility.

Muscle glycogen provides skeletal muscle with a readily available source of carbohydrate energy during exercise and daily activity. Discover how glycogenesis, glycogenolysis, insulin signaling, GLUT4, nutrition, and exercise regulate muscle glycogen storage and utilization.

Glycogenin is a specialized protein that initiates glycogen synthesis by creating a short glucose primer through self-glucosylation. The glycogenin-linked primer allows glycogen synthase to extend glucose chains, while the glycogen branching enzyme creates the α-1,6 linkages that produce mature glycogen. GYG1 and related glycogenin proteins are therefore important for glycogen structure, glucose storage, liver and muscle metabolism, and normal energy regulation.

Nitrogen metabolism is a network of biological and biochemical processes that control how nitrogen is obtained, transformed, incorporated into biomolecules, and eliminated. Explore its major pathways and their roles in organisms and ecosystems.