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8/14/2019 Lecture 2. Respiratory Control & Adaptations
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All Slides Greg D. Wells, Ph.D. (2009), All Rights ReservedWeb: www.per4m.ca Email: greg.wells@utoronto.ca Tel: 416-710-4618
Greg Wells, Ph.D.The University of Toronto
www.per4m.ca
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Part 1: The Ventilatory Responseto Exercise
Greg D. Wells, Ph.D. (2009)
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Organization of the Control of Breathing
Respiratory Rhythm Generator
(pre-Botz, VRG, NA)
Spinal Motoneurones (via
VRG & DRG)
Respiratory Muscles Lung (Pulmonary Ventilation)
Peripheral Chemoreflexes &
Lung / Airway Afferents
Nucleus of the Solitary TractReticular Activating System(Reticular Formation & Raphe)
Central Command
Central Chemoreflex
Afferent Feedback (Limbs)
Feed Forward Feed Back
Greg D. Wells, Ph.D. (2009)
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Respiratory Rhythm Generator
(pre-Botz, VRG, NA)
Spinal Motoneurones (via
VRG & DRG)
Respiratory Muscles Lung (Pulmonary Ventilation)
Peripheral Chemoreflexes &
Lung / Airway Afferents
Nucleus of the Solitary TractReticular Activating System(Reticular Formation & Raphe)
Central Command
Central Chemoreflex
Afferent Feedback (Limbs)
Wakefulness drive (cerebralcortex)
Movements signals
(cerebellum)
Type III, IV afferents (MSNA
hypothesis)
H+, PCO2, SID
(medullary surface)
H+, PCO2, PO2, K+, La-
(carotid body)
Pulmonary stretch receptors
PCO2, PO2*
*
*
Basal ventilation
(medulla)
Cross-activation
(neuronal network)
Drives to Ventilation
* Greg D. Wells, Ph.D. (2009)
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Physiology During Incremental Exercise
Greg D. Wells, Ph.D. (2009)
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Ventilation During Constant Load Exercise
Mateika, J. H. and J. Duffin (1995). A review of the control of breathing during exercise. Eur J Appl
Physiol 71(1): 1-27.
*
*
*
*
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Respiratory Rhythm Generator
(pre-Botz, VRG, NA)
Spinal Motoneurones (via
VRG & DRG)
Respiratory Muscles Lung (Pulmonary Ventilation)
Peripheral Chemoreflexes &
Lung / Airway Afferents
Nucleus of the Solitary TractReticular Activating System(Reticular Formation & Raphe)
Central Command
Central Chemoreflex
Afferent Feedback (Limbs)
Wakefulness drive (cerebralcortex)
Movements signals
(cerebellum)
Type III, IV afferents (MSNA
hypothesis)
H+, PCO2, SID
(medullary surface)
H+, PCO2, PO2, K+, La-
(carotid body)
Pulmonary stretch receptors
PCO2, PO2*
*
*
Basal ventilation
(medulla)
Cross-activation
(neuronal network)
Drives to Ventilation
*
* Shows areas where
training may have
an effect.
Greg D. Wells, Ph.D. (2009)
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Part 2: Adaptations of theRespiratory System to Training
Greg D. Wells, Ph.D. (2009)
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Organization of the Control of Breathing
Respiratory Rhythm Generator
(pre-Botz, VRG, NA)
Spinal Motoneurones (via
VRG & DRG)
Respiratory Muscles Lung (Pulmonary Ventilation)
Peripheral Chemoreflexes &
Lung / Airway Afferents
Nucleus of the Solitary TractReticular Activating System(Reticular Formation & Raphe)
Central Command
Central Chemoreflex
Afferent Feedback (Limbs)
Adaptation #1: Peripheral Chemoreflex
Greg D. Wells, Ph.D. (2009)
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Ventilation vs. Predicted PCO2
0
10
20
30
40
50
60
70
80
30 35 40 45 50 55 60
Predicted PCO2 (mmHg)
VentilationBTPS(L. min-1)
Basal Ventilation
1st VE Threshold
2nd VE Threshold
1st VE Sensitivity
2nd VE Sensitivity
Greg D. Wells, Ph.D. (2009)
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Ventilation vs. End-Tidal PCO2
0
10
20
30
40
50
60
70
30 35 40 45 50 55
End-Tidal PCO2 (mmHg)
Ventilation
BTPS(L. min-1)
Pre-training
Pre-training fitted
Post-training
Post-training fitted
Example of typical chemoreflex response pre- and post-training. The increase in
chemoreflex threshold is indicated.
EV ThresholdsChemoreflex
Greg D. Wells, Ph.D. (2009)
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Respiratory Rhythm Generator
(pre-Botz, VRG, NA)
Spinal Motoneurones (via
VRG & DRG)
Respiratory Muscles Lung (Pulmonary Ventilation)
Peripheral Chemoreflexes &
Lung / Airway Afferents
Nucleus of the Solitary TractReticular Activating System(Reticular Formation & Raphe)
Central Command
Central Chemoreflex
Afferent Feedback (Limbs)
Exercise Limiting Factors
Exercise induced arterial hypoxemia Increased work of breathing Respiratory muscle fatigue Dyspnoea
Adaptation #1: Peripheral Chemoreflex
Greg D. Wells, Ph.D. (2009)
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Organization of the Control of Breathing
Respiratory Rhythm Generator
(pre-Botz, VRG, NA)
Spinal Motoneurones (via
VRG & DRG)
Respiratory Muscles Lung (Pulmonary Ventilation)
Peripheral Chemoreflexes &
Lung / Airway Afferents
Nucleus of the Solitary TractReticular Activating System(Reticular Formation & Raphe)
Central Command
Central Chemoreflex
Afferent Feedback (Limbs)
Adaptation #2: Pulmonary Function
Greg D. Wells, Ph.D. (2009)
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Results Pulmonary FunctionFEV - 1
3.0
3.2
3.4
3.6
3.8
4.0
4.2
-1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Time (wk)
Volume(L)
F E: T2 - T3 *
F E: T2 - T4 *
F C: T2 - T4 *
F C: T2 - T3 *
2.8
3.0
3.2
3.4
3.6
3.8
4.0
4.2
4.4
-1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Time (wk)
Volume(L)
*
F E: T2 - T4 *
F E: T2 - T3 *
FIV - 1
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Results Pulmonary FunctionForced Vital Capacity
3.5
3.7
3.9
4.1
4.3
4.5
4.7
4.9
5.1
-1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Time (wk)
VitalCapa
city(L)
F E: T2 - T3 *
F C: T2 - T3 *
F C: T2 - T4 *
F E: T2 - T4 *
Audrey Ferreras
She reached a depth of 412.5
feet (125 meters) in 2minutes, 3 seconds. Greg D. Wells, Ph.D. (2009)
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Respiratory Rhythm Generator
(pre-Botz, VRG, NA)
Spinal Motoneurones (via
VRG & DRG)
Respiratory Muscles Lung (Pulmonary Ventilation)
Peripheral Chemoreflexes &
Lung / Airway Afferents
Nucleus of the Solitary Tract
Reticular Activating System
(Reticular Formation & Raphe)
Central Command
Central Chemoreflex
Afferent Feedback (Limbs)
Performance Limiting Factors
Exercise induced arterial hypoxemia Increased work of breathing Respiratory muscle fatigue Dyspnoea
Adaptation #2: Pulmonary Function
Greg D. Wells, Ph.D. (2009)
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Organization of the Control of Breathing
Respiratory Rhythm Generator
(pre-Botz, VRG, NA)
Spinal Motoneurones (via
VRG & DRG)
Respiratory Muscles Lung (Pulmonary Ventilation)
Peripheral Chemoreflexes &
Lung / Airway Afferents
Nucleus of the Solitary TractReticular Activating System(Reticular Formation & Raphe)
Central Command
Central Chemoreflex
Afferent Feedback (Limbs)
Adaptation #3: Respiratory Muscle Function
Greg D. Wells, Ph.D. (2009)
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Back
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Mechanics at Rest
-6 -2-10 -832
36
40
44
48
52
% VC
Intrapleural Pressure cm H 2O
-6 -4 -2 0 -10 -8 -4 0
lung lungthorax
wall
INSPIRATION EXPIRATION
thorax
wall
Greg D. Wells, Ph.D. (2009)
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Mechanics During ExerciseW to overcome ER Lungs W to overcome ER CW
W to overcome FR CWW to overcome L flow resist.
Greg D. Wells, Ph.D. (2009)
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RMT Mechanisms: Q Legs
Harms, C. A., M. A. Babcock, et al. (1997). Respiratory muscle work compromises leg blood flow
during maximal exercise. J Appl Physiol 82(5): 1573-83.
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Respiratory Rhythm Generator
(pre-Botz, VRG, NA)
Spinal Motoneurones (via
VRG & DRG)
Respiratory Muscles Lung (Pulmonary Ventilation)
Peripheral Chemoreflexes &
Lung / Airway Afferents
Nucleus of the Solitary Tract
Reticular Activating System
(Reticular Formation & Raphe)
Central Command
Central Chemoreflex
Afferent Feedback (Limb & RM)
Performance Limiting Factors
Exercise induced arterial hypoxemia Increased work of breathing Respiratory muscle fatigue Dyspnoea
Adaptation #3: Respiratory Muscle Function
Greg D. Wells, Ph.D. (2009)
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Respiratory Rhythm Generator
(pre-Botz, VRG, NA)
Spinal Motoneurones (via
VRG & DRG)
Respiratory Muscles Lung (Pulmonary Ventilation)
Peripheral Chemoreflexes&
Lung / Airway Afferents
Nucleus of the Solitary Tract
Reticular Activating System
(Reticular Formation & Raphe)
Central Command
Central Chemoreflex
Afferent Feedback (Limbs)
Performance Limiting Factors
Exercise induced arterial hypoxemia Increased work of breathing Respiratory muscle fatigue Dyspnoea
Adaptation #4: Dyspnoea
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Pulmonary stretch
receptors
Central & peripheral
chemoreceptorsType I afferents M+ spindles
(length ~ volume)
Type II afferents GTO (tension
~ pressure: Pdi / Pmax)
Type III afferents M+ spindles
(contraction ~ V, Fb, Ti:Te)
Type IV afferents M+ spindles
(metaboreceptors ~ H+, K+)
Dyspnoea Mechanisms
Greg D. Wells, Ph.D. (2009)
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Dyspnoea Typical Application
Greg D. Wells, Ph.D. (2009)
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Pulmonary stretch
receptors
Central & peripheral
chemoreceptors
Type I afferents M+ spindles(length ~ volume)
Type II afferents GTO (tension
~ pressure: Pdi / Pmax)
Type III afferents M+ spindles
(contraction ~ V, Fb, Ti:Te)
Type IV afferents M+ spindles(metaboreceptors ~ H+, K+)
Pathogenesis of Dyspnoea
Hypoxia / hypercapnia
Dynamic hyperinflation
Dynamic hyperinflation
Dynamic hyperinflation
(lose mechanical adv)
RM weakness (Pmax)
Hyperventilation
RM fatigue
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Organization of the Control of Breathing
Respiratory Rhythm Generator
(pre-Botz, VRG, NA)
Spinal Motoneurones (via
VRG & DRG)
Respiratory Muscles Lung (Pulmonary Ventilation)
Peripheral Chemoreflexes &
Lung / Airway Afferents
Nucleus of the Solitary TractReticular Activating System(Reticular Formation & Raphe)
Central Command
Central Chemoreflex
Afferent Feedback (Limbs)
Summary
Greg D. Wells, Ph.D. (2009)
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