Automatic System |
Rhythmic discharge of brain stem respiratory neurons located
in the medulla and pons (respiratory center) produces automatic respiration.
Corollary discharge reports to sensory cortex where respiratory effort
is sensed.
Efferent output from respiratory motor neurons located in spinal cord
reciprocally activates muscles of inspiration and of expiration. |
Discharge is rhythmic and automatic (most efficient and
with least effort).
The person is not usually not aware of breathing. |
Voluntary System |
Discharge from cerebral (motor) cortex activates respiratory motor
neurons via corticospinal tract.
Corollary discharge goes to sensory cortex. |
Afferent discharge is from the motor cortex (less efficient and more
effort).
The person usually aware of breathing. |
Afferent Inputs |
Afferent inputs from chemoreceptors (blood and brain) as well as mechanoreceptors
(airways, lungs and chest wall) integrate into the respiratory center
for feedback and adjustment of respiratory patterns.
These afferent inputs may also project to higher brain centers to provide
a direct appraisal of the chemical milieu of the body and of the mechanical
status of the ventilatory apparatus. |
Increased progesterone and salicylic poisoning change the rate of breathing,
predominantly through chemo-receptors.
Obstructive and restrictive lung diseases mediate breathing, predominantly
through mechano-receptors.
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