Control of Breathing
Monday, 20 September 2021 5:01 PM
Neural control of breathing
- Sensors
o Gather and collect information
o Send to brain where central controller is located
- Central controller
o Pons / medulla
o Important for the coordination of neural activity
- Effector
o Relay activity to diaphragm / respiratory muscles
o Responsible for activity during active expiration and inspiration
Central controllers
- Medulla oblongata
o Inspiratory centre
§ Motor centre for inspiration
o Expiratory centre
§ Motor centre for expiration
- In pons
o Pneumotaxic centre – upper pons
§ Quickens transition from inspiration to expiration
o Apneustic center – middle /lower pons
§ slows change from inspiration from expiration
§ Makes transition more difficult
- control of breathing
o regular rhythmic breathing pattern under neurogenic control
o respiratory centers
§ motor centers – medulla oblongata
§ coordinating center – pons
• Coordinate the transitions from inspiration to expiration
o neural pathways
§ vagal nerve sends negative feedback activity for the transition between
inspiration and expiration
• Pneumotaxic feedback to stop inspiration
§ herring breur reflex
• negative feedback to stop inspiration and facilitate transition
• Prevents over inflation of the lungs
• Stretch receptors respond to stretching during inspiration
o receptors
§ responds to the stretch of the lung during inspiration
• activated stretch receptor when lung is expanded
• neural activity sent to respiratory sensor through vagal nerve to
, • Prevents over inflation of the lungs
• Stretch receptors respond to stretching during inspiration
o receptors
§ responds to the stretch of the lung during inspiration
• activated stretch receptor when lung is expanded
• neural activity sent to respiratory sensor through vagal nerve to
inhibit inspiration
o reflex pathway
chemoreceptors
- peripheral chemoreceptors
o sensitive to the chemicals involved in respiration
o aortic and carotid bodies
§ biphalcation of carotid artery
o increased chemo-sensitive cell activity by increasing ventilation
§ lower oxygen level / pH / high CO2 / low blood flow / high temp / drugs
§ hypoxemia
§ causes increase in ventilation
o decrease activity when
§ higher oxygen level / pH / low CO2 / high blood flow / low temp / drugs
§ Decreases ventilation
- central chemoreceptors
o Medulla
§ lower brain stem
o it does not respond to oxygen level
o only to pH, CO2 level, blood flow, temperature, drugs
o affects ventilation by affecting frequency and tidal volume
Pulmonary receptors
- irritant receptors
o Found in air way epithelium
o responds to irritants – dust
o illicit airway reflexes – coughing
o receptor activity increases in diseased conditions
§ Chemical / mechanical irritations, pneumothorax, pulmonary
congestions, asthma
o stimulates increase in ventilation
§ increasing breathing frequency
§ decreases tidal volume
§ shallow breathing
- stretch receptors
o Found in smooth muscles of airways
o Regulates breathing rhythm
o herring-breuer reflex
- type J receptors
o juxta-pulmonary capillary receptors in alveolar wall
o stimulated by
§ increases interstitial volume
§ Chemical injury
§ Pathological conditions
o increase ventilation by stimulating frequency and decreases TV
Monday, 20 September 2021 5:01 PM
Neural control of breathing
- Sensors
o Gather and collect information
o Send to brain where central controller is located
- Central controller
o Pons / medulla
o Important for the coordination of neural activity
- Effector
o Relay activity to diaphragm / respiratory muscles
o Responsible for activity during active expiration and inspiration
Central controllers
- Medulla oblongata
o Inspiratory centre
§ Motor centre for inspiration
o Expiratory centre
§ Motor centre for expiration
- In pons
o Pneumotaxic centre – upper pons
§ Quickens transition from inspiration to expiration
o Apneustic center – middle /lower pons
§ slows change from inspiration from expiration
§ Makes transition more difficult
- control of breathing
o regular rhythmic breathing pattern under neurogenic control
o respiratory centers
§ motor centers – medulla oblongata
§ coordinating center – pons
• Coordinate the transitions from inspiration to expiration
o neural pathways
§ vagal nerve sends negative feedback activity for the transition between
inspiration and expiration
• Pneumotaxic feedback to stop inspiration
§ herring breur reflex
• negative feedback to stop inspiration and facilitate transition
• Prevents over inflation of the lungs
• Stretch receptors respond to stretching during inspiration
o receptors
§ responds to the stretch of the lung during inspiration
• activated stretch receptor when lung is expanded
• neural activity sent to respiratory sensor through vagal nerve to
, • Prevents over inflation of the lungs
• Stretch receptors respond to stretching during inspiration
o receptors
§ responds to the stretch of the lung during inspiration
• activated stretch receptor when lung is expanded
• neural activity sent to respiratory sensor through vagal nerve to
inhibit inspiration
o reflex pathway
chemoreceptors
- peripheral chemoreceptors
o sensitive to the chemicals involved in respiration
o aortic and carotid bodies
§ biphalcation of carotid artery
o increased chemo-sensitive cell activity by increasing ventilation
§ lower oxygen level / pH / high CO2 / low blood flow / high temp / drugs
§ hypoxemia
§ causes increase in ventilation
o decrease activity when
§ higher oxygen level / pH / low CO2 / high blood flow / low temp / drugs
§ Decreases ventilation
- central chemoreceptors
o Medulla
§ lower brain stem
o it does not respond to oxygen level
o only to pH, CO2 level, blood flow, temperature, drugs
o affects ventilation by affecting frequency and tidal volume
Pulmonary receptors
- irritant receptors
o Found in air way epithelium
o responds to irritants – dust
o illicit airway reflexes – coughing
o receptor activity increases in diseased conditions
§ Chemical / mechanical irritations, pneumothorax, pulmonary
congestions, asthma
o stimulates increase in ventilation
§ increasing breathing frequency
§ decreases tidal volume
§ shallow breathing
- stretch receptors
o Found in smooth muscles of airways
o Regulates breathing rhythm
o herring-breuer reflex
- type J receptors
o juxta-pulmonary capillary receptors in alveolar wall
o stimulated by
§ increases interstitial volume
§ Chemical injury
§ Pathological conditions
o increase ventilation by stimulating frequency and decreases TV
