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Unformatted text preview: Lecture 9: Regulation of the Respiration • Practice Questions : o “Former students in Systems who’ve done well, suggests which of the following is correct” • Overview of Respiratory Control Systems : o there is both neuro (higher CNS) and chemical (P’s) component to regulation of respiration o Neuro Control: cardiovascular control centers in medulla o chemical control : changes in blood gases ph is not a blood gas! • but it’s affected by PCO2 so it’s included as blood gas changes—elevated CO2 (hypercapnia), reduced PO2 and pH— affect 2 different components of the respiratory control system: • Peripheral chemo-receptors : located in blood vessels • central chemoreceptors : located in brain stem o For example: imagine partial pressure of oxygen in arterial blood decreases all the system combined will lead to ventilation hyperventilation will lead to a correction of the hypoxia (decrease in blood) • History: Galen of Pergamon and the Gladiators of the High Priest of Asia o AD 129 – 200 (birth and death) o physician/surgeon to gladiators to treat wounds for 4 years o dogma of medicine for 16 centuries no one opposed what gamon thought in the past bc it would lead to death o influence on though re. CNS regulation of respiration ~18-19 centuries • Effect of Transecting Brainstem on Respiratory Patterns o One of things observed by Galen with wounds in spinal cord c1-c3 (high cervical spinal cord): stopped breathing • animal lost ability to breath c5-c7 (low cervical spinal cord): always breathing but paralyzed If he did transection of the neuraxis, Galen concluded that there was a signal sent through the mid cervical region of the spinal cord that enabled the diaphragm and the respiratory muscles of thorax to operate He didn’t research the pons and medulla for additional info o Lungsdon observed: if a transection was made above spinal column but below the pons • could record nerve activity in cranial nerves and Phrenic nerve • Phrenic nerves : moves diaphragm Slide 1 Slide 2 Slide 3 if transected lower than pons : • AP in central nerves but no AP in Phrenic nerves must be respiratory neurons in medulla that control accessory muscles of respiration o Central Pattern Generator : neurons that lead to the rhythmic inspiration and expiration respiratory cycle drives rhythmic respiratory cycle • Respiratory Control Centers: o 2 dorsal views of the medulla, lower pons, and cervical spinal column o cerebellum removed in both o yellow region = 4 th ventricle o Inspiratory Neurons vs. Expiratory Neurons many pools of inspiratory neurons fewer pools of expiratory neurons in medulla o DRG (dorsal respiratory group) most of inspiratory neurons located here both dorsal and medially located cell bodies has motor axons descending to innervate the phrenic nerve and the spinal nerves for the intercostals muscles any severing of theses nerves would mess up the inspiratory...
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- Fall '08
- central pattern generator, respiratory control