13. Control of respiration

• What group of cells control the diaphragm during tidal inspiration?

  Dorsal respiratory group
• Dorsal respiratory group (DRG) are composed of cells in the nucleus tractus solitarius
• Dorsal respiratory group - respond to lung volume
• Pneumotaxic Center function

  • limits duration of inspiration
  • increases respiratory rates
• Pneumotaxic Center is located?

  nucleus parabrachialis of upper pons
• Pneumotaxic Center sends signal to inspiratory area
• Pneumotaxic Center act like a "switch off" point of inspiratory ramp

  • control duration of respiratory cycle

  
• Apneustic center is located in lower pons
• Apneustic center - Facilitate apneusis or prolonged inspiratory gasp

  • site of afferent info that terminate inspiration
• Apneustic breath is seen after head trauma that damages the pons
• When is ventral respiratory group inactive?

  during tidal respiration
• Ventral respiratory group (VRG) function during inspiratory/expiratory overdrive
• Ventral respiratory group - Composed of three cell group

  1. rostral nucleus retrofacialis
  2. nucleus para-ambiguous
  3. caudal nucleus retroambiguus
• • Rostral nucleus retrofacialis - expiratory neuron
  • Contain Botzinger complex - inhibit inspiratory cells in DRG
• • Nucleus para-ambiguous - vagal motoneuron
  • Control laryngeal and pharyngeal muscles during both inspiration and exhalation
• Caudal nucleus retroambiguus - contain inspiratory and expiratory neuron

  • Control contralateral internal/external intercostals and abdominal muscles
• Chemoreceptors respond to change in chemical in the fluid around it
• Central chemoreceptor - located in the ventrolateral surface of the medulla
• Central chemoreceptors are sensitive to changes in PCO2 and pH of the CSF
• CO2 in blood regulates ventilation by?

  effect on pH of CSF
• How to stimulate central chemoreceptor?

  increase H+ or PCO2 = decrease CSF pH --> result in increase ventilation
• Increase H+ or PCO2 = increase ventilation
• decrease CSF pH will increase ventilation
• BBB is impermeable to H+ and HCO3, but permeable to CO2
• where are the peripheral chemoreceptor located?

  • Carotid (CN 9 petrosal ganglion)
  • Aortic bodies (CN 10 nodose)
• Peripheral chemoreceptor respond to? - In Arterial (blood)

  • Decrease in PO2
  • Increase PCO2
  • Decrease pH
• Peripheral chemoreceptor send info to?

  central respiratory control center
• peripheral chemoreceptor

  • strongly stimulated when PaO2 falls below normal
  • no effect when PaO2 > 100 mmHg
• which chemoreceptor is the stronger?

  central
• A stretch in rapidly adaptive pulmonary receptors function?


  irritant receptor in the trachea and large airway
• Rapidly adaptive pulmonary stretch receptor - sense irritated gases

  • the body adapt by
  • increase airway resistance
  • reflex apnea
  • cough
• Slow and rapid pulmonary stretch receptor send their info through?


  myelinated vagal afferent fibers
• Slowly adapting pulmonary stretch receptor

  • Respond to mechanical stimulation
  • Activated by lung inflation
• Slowly adapting pulmonary stretch receptor function by

  • increasing lung volume in people with COPD stimulates these pulmonary stretch receptor
  • delays the onset of next inspiratory efforts
• Juxta-alveolar receptor or J receptor are found in the lung parenchyma
• Juxta-alveolar receptor or J receptor

  • Respond to chemical or mechanical stimulation in the lung interstitium
  • Transmit their afferent input through unmyelinated, vagal C fibers
• Juxta-alveolar receptor or J receptor

  • Responsible for
  • sensation of dyspnea (SOB)
  • Altered ventilation pattern (rapid, shallow)
• Juxta-alveolar receptor or J receptor

  • Seen in individual with
  • interstitial lung edema
  • Inflammatory lung states
• Hering-Breuer deflation reflex is associated with an increase in ventilatory rate due to abrupt lung deflation
• Hering-Breuer deflation reflex

  • Function
  • Decreased stretch receptor activity
  • Stimulate other receptor such as J receptor