24.10 Respiratory Centers of the Brain

• • Respiratory centers within the brain regulate the activities of the respiratory muscles by adjusting the frequency and depth of pulmonary ventilation.
• Under normal conditions, oxygen absorption and carbon dioxide generation are matched because of the rates of oxygen delivery and carbon dioxide removal by the capillary beds
• Regulatory centers coordinating the responses by these systems are located in the pons and medulla oblongata
• The respiratory centers are three pairs of loosely organized nuclei in the reticular formation of the pns and medulla oblongata
• These nuclei regulate the activities of the respiratory muscles by adjusting the frequency and depth of pulmonary ventilation
• The respiratory rhythmicity centers set the basic pace and depth of respiration
• Respiratory rhythmicity centers are subdivided into a dorsal respiratory group (DRG) and a ventral respiratory group (VRG)
• The dorsal respiratory group, or inspiratory center, controls motor neurons innervating the external intercostal muscles and the diaphragm
• The ventral respiratory group functions only during forced respiration
• Ventral respiratory group innervates motor neurons controlling accessory muscles involved in active exhalation and maximal inhalation
• Neurons involved with active exhalation are sometimes called an expiratory center
• The apneustic centers and pneumotaxis centers of the pons are paired nuclei that adjust the output of the rhythmicity center
• Three different reflexes are involved in regulating respiration:

  • mechanoreceptor reflexes respond to changes in the volume of the lungs or to changes in arterial blood pressure
  • chemoreceptor reflexes respond to changes in the pH of the blood and cerebrospinal fluid
  • protective reflexes respond to physical injury or irritation of the respiratory tract
• SUMMARY

  • Respiratory centers are three pairs of nuclei in reticular formation of the pons and medulla. Respiratory rhythmicity centers set the pace for respiration. Apneustic center causes strong, sustained inspiratory movements, and pnemotaxic center inhibits apneustic center and inspiratory center in medulla oblongata.
• SUMMARY

  • Three different reflexes are involved in regulation of respiration: (1) Mechanoreceptor reflexes respond to changes in volume of lungs or to changes in arterial blood pressure; (2) chemoreceptor reflexes to respond to changes in blood and cerebrospinal fluid; and (3) protective reflexes respond to physical injury or irritation of respiratory tract.
  • Conscious and unconscious thought processes can also control respiratory activity by affecting the respiratory centers or controlling respiratory muscles.
• Stimulation of which respiratory centers would increase the rate and depth of breathing?

  Stimulation of the apneustic and pneumotaxic centers would result in an increased rate and depth of breathing.