💪

Endocrine System's Role in Exercise Metabolism

Oct 12, 2024

Lecture Notes on Endocrine System and Exercise Metabolism

Key Glands Involved in Exercise Metabolism

  • Anterior Pituitary Gland

    • Secretes hormones based on hypothalamic stimulating and inhibitory hormones.
    • Increases secretion of all anterior pituitary hormones during exercise.
    • Growth Hormone
      • Promotes muscle hypertrophy and tissue building.
      • Increases fat metabolism and blood free fatty acid levels.
      • Helps in sparing glucose by increasing fat utilization.
      • Release proportional to exercise intensity.
  • Thyroid Gland

    • Releases Triiodothyronine (T3) and Thyroxine (T4) both at rest and during exercise.
    • Increases metabolic rate, protein synthesis, glucose uptake and utilization.
    • Enhances fatty acid availability and aerobic metabolism.
    • Increases number and size of mitochondria over time.
  • Adrenal Glands

    • Adrenal Medulla
      • Releases norepinephrine and epinephrine, mostly epinephrine (80%).
      • Stimulates sympathetic nervous system during exercise.
      • Prolonged action due to circulation in the bloodstream.
      • Increases heart rate, contractility, blood pressure, respiration, metabolism, and glycogenolysis.
      • Facilitates blood flow redistribution to active skeletal muscles through vasoconstriction.
    • Adrenal Cortex
      • Releases corticosteroids: glucocorticoids, mineralocorticoids, and gonadocorticoids.
      • Cortisol (main glucocorticoid)
        • Increases gluconeogenesis and free fatty acid availability.
        • Enhances protein catabolism and decreases glycolysis.
        • Acts as anti-inflammatory, sparing glucose for the brain.
        • Released after ~30 mins of moderate-intensity exercise.
  • Pancreas

    • Primary organ controlling blood glucose at rest and during exercise.
    • Releases Insulin when blood glucose is high.
      • Facilitates glucose transport into cells, decreasing blood glucose.
      • Promotes glycogen, protein, and fat synthesis; decreases lipolysis and gluconeogenesis.
    • Releases Glucagon when blood glucose is low.
      • Increases glucose release from liver and skeletal muscle, enhancing glycogenolysis and gluconeogenesis.

Importance of Blood Glucose

  • Blood glucose is crucial for body functions during exercise.
  • Insulin secretion decreases during exercise to manage glucose use.
  • A follow-up discussion on glucose entry into muscle cells will be addressed in another video.