Regulation is done by two seperate mechanisms,:
a) Voluntary Mechanism
b) Autonomic Mechanism
a) Voluntary mechanism consists of:
1) Cerebral Cortex
Role:
– Voluntary Hyper ventilation.
– Breath holding
2) Other parts of Brain
– Hypothalamus
– Limbic system (Rage & Fear)
These project to the respiratory muscles via the corticospinal tract.
b) Autonomic Mechanism /Respiratory Center in Brain Stem:
Composed of:
1. Medullary respiratory center
i) Dorsal respiratory group (DRG) of neurons
Site: Dorsal region of Medulla Nucleus Tractus solitarius
Role: Inspiration
Mechanism:
– Intrinsic periodic firing
– Insp. ramp signals
(Inhibited by Pneumotaxic Center)
ii) Ventral respiratory group (VRG) of neurons
Site:
5 mm Ant & Lat. to Dorsal respiratory group of neurons in Nucleus ambiguus & Retro ambiguus
Role: – Quiescent during quiet breathing
– Expiration during exercise
2. Apneustic center
Site:
In lower Pons
Role:
– Excitation of inspiratory area.
– Prolonging of Insp. ramp.
3 .Pneumotaxic center
Site: Parabrachial nucleus
Role:
-Inhibits Inspiration by “Switching off” Insp. ramp.
Pre- Botzinger complex located on either side of medulla DRGN & VRGN in medulla project to the pre- Botzinger
pacemaker neurons.Pre-Botzinger neurons discharge rhythmically and produce rhythmical discharges in Phrenic nerves (respiration).
The Herring-Brewer reflex also controls respiration neurally.
Mechanism of Regulation:
Sensors (baroreceptors, chemoreceptors etc.) ------>Central Nervous System (medulla, pons) -------> Effector Organ (respiratory muscles)
a) Voluntary Mechanism
b) Autonomic Mechanism
a) Voluntary mechanism consists of:
1) Cerebral Cortex
Role:
– Voluntary Hyper ventilation.
– Breath holding
2) Other parts of Brain
– Hypothalamus
– Limbic system (Rage & Fear)
These project to the respiratory muscles via the corticospinal tract.
b) Autonomic Mechanism /Respiratory Center in Brain Stem:
Composed of:
1. Medullary respiratory center
i) Dorsal respiratory group (DRG) of neurons
Site: Dorsal region of Medulla Nucleus Tractus solitarius
Role: Inspiration
Mechanism:
– Intrinsic periodic firing
– Insp. ramp signals
(Inhibited by Pneumotaxic Center)
ii) Ventral respiratory group (VRG) of neurons
Site:
5 mm Ant & Lat. to Dorsal respiratory group of neurons in Nucleus ambiguus & Retro ambiguus
Role: – Quiescent during quiet breathing
– Expiration during exercise
2. Apneustic center
Site:
In lower Pons
Role:
– Excitation of inspiratory area.
– Prolonging of Insp. ramp.
3 .Pneumotaxic center
Site: Parabrachial nucleus
Role:
-Inhibits Inspiration by “Switching off” Insp. ramp.
Pre- Botzinger complex located on either side of medulla DRGN & VRGN in medulla project to the pre- Botzinger
pacemaker neurons.Pre-Botzinger neurons discharge rhythmically and produce rhythmical discharges in Phrenic nerves (respiration).
The Herring-Brewer reflex also controls respiration neurally.
Mechanism of Regulation:
Sensors (baroreceptors, chemoreceptors etc.) ------>Central Nervous System (medulla, pons) -------> Effector Organ (respiratory muscles)