Neural regulation


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Neural regulation

  1. 1. Neural regulationD.A. Asir John Samuel, BSc (Psy), MPT (Neuro Paed), MAc, DYScEd, C/BLS, FAGE Lecturer, Alva’s college of Physiotherapy, Moodbidri Dr.Asir John Samuel (PT)
  2. 2. Respiratory center• Group of neurons located bilaterally in medulla oblongata and pons• Dorsal respiratory group – inspiration• Ventral respiratory group – ins/exp• Pneumotaxic center, located dorsally in superior portion of pons, rate and pattern Dr.Asir John Samuel (PT)
  3. 3. Dr.Asir John Samuel (PT)
  4. 4. Respiratory center Dr.Asir John Samuel (PT)
  5. 5. Chemical control• Ultimate goal is to maintain proper concentrations of oxygen, carbon dioxide and hydrogen ions in tissues• Excess CO2 or H+ in blood act on respiratory center Dr.Asir John Samuel (PT)
  6. 6. Chemical control• Causes increased strength of both inspiratory and expiratory motor signals to respiratory muscles• O2 does not have significant direct effect on respiratory center• Acts on peripheral chemoreceptors located in carotid and aortic bodies Dr.Asir John Samuel (PT)
  7. 7. Dr.Asir John Samuel (PT)
  8. 8. Direct chemical control• A sensitive chemosensitive area, located B/L lying 1/5th mm beneath ventral surface of medulla• Highly sensitive to changes in either blood PCO2 or H+ concentration• In turn excites the other portion of respiratory center Dr.Asir John Samuel (PT)
  9. 9. H+ - the primary stimulus• Sensor neurons in chemosensitive area are especially excited by H+• Direct stimulation• Does not cross BBB• Less effect in stimulating than do changes in blood CO2 Dr.Asir John Samuel (PT)
  10. 10. Effect of blood CO2• Little direct and indirect effect in stimulating• Cross BBB• When blood PCO2 increases, PCO2 of CSF and interstitial fluid of medulla increases• Immediately reacts with water• Dissociates into carbonic acid and H+ Dr.Asir John Samuel (PT)
  11. 11. Dr.Asir John Samuel (PT)
  12. 12. Chemical control CO2 crosses BBBIncrease Blood PCO2,increases PCO2 of CSF and interstitial fluid of Medulla Immediately reacts with H2O H2CO3 Dissociates into H+ + HCO3_ Dr.Asir John Samuel (PT)
  13. 13. Peripheral chemoreceptor system• Detects changes in O2 in blood• Responds lesser to changes in CO2 and H+• Carotid bodies and aortic bodies• Some in thoracic and abdominal regions Dr.Asir John Samuel (PT)
  14. 14. Peripheral chemoreceptors• Carotid bodies are located B/L in bifurcations of common carotid arteries• Afferent nerve, Hering’s nerves to IX and X• DRG of neurons in medulla• Aortic bodies are located along the arch of aorta• Afferent nerve fiber passes through X Dr.Asir John Samuel (PT)
  15. 15. Stimulation peripheral chemoreceptors• Richly vascularised• 20 times weight of bodies• Removal of O2 is virtually 0• All times exposed to arterial blood• Glomus cell, glandular cell• PO2 changes from 60 down to 30 mm Hg• Increases respiratory activity• 5 times than central Dr.Asir John Samuel (PT)