Carbohydrate Metabolism

• Glucose is essential for:

  • Connective Tissue
  • Molecules
  • Energy production
  • Pyruvate
  • Lactate
  • Blood Group Substances
  • Cholesterol and Fatty Acid Synthesis
  • Antioxidant effect
  • Glycogen
  • Nucleic acids
  • Glycolipid
  • Glycoprotein
• Normal fasting blood glucose levels:

  • Between 80-100 mg/dL (4.6-6.1 mmol/L)
  • Should not exceed ≥140 mg/dL (7.8 mmol/L) 2 hours after a meal
• The Citric Acid Cycle (TCA) explains the relationship between nutrients, air oxygen, and ATP

  • Priority is given to Glucose in the Cycle
  • Fatty acids entering the cycle first can lead to blood pH drops and acidosis
• Insulin deficiency can lead to:

  • Weight loss
  • Polyuria
  • Polydipsia
  • Blood sugar rise
  • Symptoms of Diabetes Mellitus
• Insulin:

  • Main hormone with a hypoglycemic effect
  • Regulates glucose-related metabolic pathways
  • Anabolic hormone storing carbohydrates, lipids, and affecting protein synthesis positively
• Glucose absorption process:

  • Glucose enters cells of the small intestine with sodium
  • ATP required for glucose transport against concentration gradient
  • Sodium shifts into extracellular space while glucose enters capillaries
• Fate of Glucose after absorption:

  • Glucose released into blood rises up to renal threshold of 160 mg
  • Excess glucose attaches to proteins, affecting protein functions
  • HbA1c test measures glucose binding to proteins and organ damage
• Glucose Tolerance Test:

  • Common test to examine sugar fate after absorption
  • Helps understand type of diabetes
  • Requires specific test administration protocol for reliable results
• Fate of Glucose entering the cell:

  • Stored as glycogen or used for energy production
  • Excess stored as glycogen through glycogenesis
  • NADPH produced in Pentose Phosphate Pathway for various syntheses
  • Gluconeogenesis pathway for glucose synthesis
• Glycogen Production and Destruction Pathway:

  • Excess glucose stored as glycogen by glycogen synthase
  • Glucuronic acid produced in this pathway for detoxification
  • Breakdown pathway involves enzymes like phosphorylase and phosphatase
• TCA and Glucose Relationship:

  • Glucose is primary energy source for cells
  • Broken down into lactate without oxygen, producing 2 ATP
  • With oxygen, lactic acid converted to acetyl CoA for TCA entry
  • Hydrogens from glucose transported to oxygen via B vitamins in TCA
• In single-celled organisms, substances can easily enter the cell due to a short distance, while in multicellular organisms, the distance is larger because of a higher surface area to volume ratio
• Multicellular organisms require specialised exchange surfaces for efficient gas exchange of carbon dioxide and oxygen due to their higher surface area to volume ratio
• The oxidation of glucose and the formation of CO2, H2O, and ATP is a vital process in organisms
• Glucose is essential for obtaining pentoses required for DNA and RNA
• The pentose phosphate pathway is crucial for producing products with antioxidant properties
• Deficiency of enzymes in the pentose phosphate pathway can lead to hemolytic anemia
• Erythrocytes survive with ATP produced by glycolysis, not the citric acid cycle
• Glycolysis and the pentose phosphate pathway are interconnected
• Glycolysis is necessary for the production of 2,3 diphosphoglycerate (2,3DPG) which is crucial for oxygen release to tissues
• The Bohr effect influences the oxygen binding curve of hemoglobin under certain pressures
• Glycolysis is essential for the production of 2,3 diphosphoglycerate (2,3DPG) which is vital for oxygen release to tissues
• Gluconeogenesis is the synthesis pathway of glucose from non-carbohydrate molecules
• Insulin plays a crucial role in maintaining blood glucose levels within reference values
• Glucagon and adrenaline act in opposition to insulin, raising blood glucose levels
• Glucocorticoids like cortisone increase blood sugar levels by accelerating the pathway of glucose synthesis
• Hyperthyroidism leads to high blood glucose levels, while hypothyroidism results in low blood glucose levels