Control of Ventilation Flashcards
Where is the Dorsal Respiratory Group (DRG) of neurons located?
Medulla
Where do DRG afferent signals come from and where does it send efferent signals?
Afferents: come from both mechanoreceptors and chemoreceptors, apneustic center and pneumotaxic center
Efferents: sent to spinal cord which sends signals to INSPIRATORY muscle motor neurons only
Where is the Ventral Respiratory Group (VRG) located?
Medulla
Where do VRG afferent signals come from and where does it send efferent signals?
Afferents: mainly come from DRG
Efferents: sent to spinal cord which signals both inspiratory AND expiratory muscle motor neurons
Where is the Pre-Botzinger complex and what does it do?
Located in the medulla
-regulates respiratory pattern (pacemaker)
Where is the apneustic center located and what is its function?
Pons
-prevents inhibition of inspiratory neurons (stimulates inspiration)
Where is the pneumotaxic center located and what is its function?
Pons
-inhibits inspiration
What are the 3 pulmonary receptors and how do they function?
- Slowly Adapting Pulmonary Stretch Receptors(PSR)
- Rapid Adapting PSR
- C-fiber receptors
-all are mechanoreceptors involved in protective reflexes that send afferents to the DRG via the Vagus Nerve (CN X)
Where are Slowly Adapting PSRs located and how do they function?
- Located in airway smooth muscle
- Respond to distension of the lungs by inhibiting inhalation and prolonging exhalation
What is the Hering-Breur Reflex?
Inflation reflex preventing large tidal volumes. Occurs when the Slowly Adapting PSRs are stimulated. More common in infants.
Where are Rapid Adapting PSRs located and how do they function?
Located between airway epithelial cells
- respond to noxious gases, cigarette smoke, dust
- involved in coughing reflex, mucous production, bronchoconstriction
Where are the C-fiber receptors located and how do they function?
Located in alveoli and conducting airways next to the capillaries (Juxtacapillary Receptors).
- respond to lung injury or overinflation (either chemical or mechanical)
- involved in initiating slow shallow breathing
What are the two peripheral chemoreceptors?
Carotid and Aortic Bodies
2 metabolites monitored by the peripheral chemoreceptors.
- O2
- H+
- CO2 (very minor)
Where are the central chemoreceptors located?
Medulla
Main metabolite monitored by the central chemoreceptors.
CO2
- indirectly monitored
- CO2 crosses BBB and increases the concentration of H+ (lower pH)
- chemoreceptors respond to the lower pH
Small fluctuations in CO2 concentration have large effects on ventilation in both depth and rate. Why does oxygen fluctuation NOT have as big of an influence?
Hb saturation remains high for a wide range of O2 pressures. Only when the O2 pressure falls below 60mmHg and Hb oxygen saturation falls below 90% does ventilation change.
What is the major regulator of ventilation at high altitude.
O2 pressure
Why does breathing at a higher altitude often result in respiratory alkalosis?
The lower pressure of Oxygen that is inhaled results in increased respiratory rate which expels more CO2 resulting in an increased pH.
What are the two mechanisms to compensate for the respiratory alkalosis caused at high altitude?
- Renal Compensation: kidneys secrete more bicarb
2. CSF Compensation: CSF transport bicarb out into systemic circulation
