Involuntary Regulation of Breathing

Jun 25, 2024

Involuntary Regulation of Breathing

Anatomy of Breathing Muscles

  • Rib Cage Muscles: Intercostal muscles
  • Diaphragm: Key muscle under the rib cage

Mechanism of Breathing

  • Inhalation/Exhalation: Muscles contract and relax
  • Brain Signals: Required for muscle contraction

Voluntary vs Involuntary Breathing

  • Voluntary Breathing: Control over breathing (e.g., holding breath underwater)
  • Involuntary Breathing: Happens without conscious effort (e.g., breathing during sleep)
  • Conclusion: Breathing is both voluntary and involuntary, focus on involuntary regulation

Brain Regions Controlling Breathing

  • Pons and Medulla Oblongata: Lower part of the brain
  • Neurons Involved:
    • Dorsal Respiratory Group (DRG): Located in medulla oblongata, controls diaphragm & intercostal muscles
    • DRG Function: Fires constant nerve impulses for muscle contraction (inhalation)
    • Pneumotaxic Center: Located in pons, switches off DRG for exhalation (3-5 secs)
    • Rate of Breathing: Pneumotaxic center switches off DRG 12-16 times/minute

Response to Physical Exercise

  • Increased Breathing Rate: During exercise
  • CO2 Production: Increased during physical activity
  • Blood Acidity: High CO2 lowers pH (more acidic)
  • Chemoreceptors:

    • Peripheral Chemoreceptors: Located in carotid artery & aortic arch, detect increased H+ and CO2

    • Central Chemoreceptors: Located near medulla, detect changes in cerebrospinal fluid

Action of Chemoreceptors

  • Signal Transmission: Send signals to the pneumotaxic center
  • Pneumotaxic Response: Increases rate and depth of breathing

Key Points

  • Neural Control: Involves DRG (medulla) and pneumotaxic center (pons)
  • Chemical Control: Involves chemoreceptors detecting changes in blood and cerebrospinal fluid
  • Combined Effort: Both neural and chemical controls regulate involuntary breathing

Summary

  • Neural Control: DRG initiates inhalation; pneumotaxic center controls exhalation
  • Chemical Control: Chemoreceptors respond to CO2/H+ levels, impacting breathing rate/depth

Important Terms

  • DRG (Dorsal Respiratory Group): Medulla, initiates inhalation
  • Pneumotaxic Center: Pons, controls exhalation
  • Peripheral Chemoreceptors: Carotid artery, aortic arch
  • Central Chemoreceptors: Near medulla, cerebrospinal fluid