Neural Substrates of Breathing

1. Medulla Respiratory Centers
• Inspiratory Center (Dorsal Resp Group - rhythmic breathing) ----> phrenic nerve ----> intercostal nerves ----> diaphragm + external intercostals
  
• Expiratory Center (Ventral Resp Group - forced expiration) ----> phrenic nerve ----> intercostal nerves ----> internal intercostals + abdominals (expiration)
1. eupnea - normal resting breath rate (12/minute)
2. drug overdose - causes suppression of Inspiratory Center
2. Pons Respiratory Centers
1. pneumotaxic center - slightly inhibits medulla, causes shorter, shallower, quicker breaths
2. apneustic center - stimulates the medulla, causes longer, deeper, slower breaths
3. Control of Breathing Rate & Depth
1. breathing rate - stimulation/inhibition of medulla
2. breathing depth - activation of inspiration muscles
3. Hering-Breuer Reflex - stretch of visceral pleura that lungs have expanded (vagal nerve)
4. Hypothalamic Control - emotion + pain to the medulla
5. Cortex Controls (Voluntary Breathing) - can override medulla as during singing and talking

Category: Physiology Notes