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The respiratory center (RC) is located in the medulla oblongata and pons, which are part of the brain stem. The RC receives controlling signals of neural, chemical and hormonal nature and controls the rate and depth of respiratory movements of the diaphragm and other respiratory muscles. Injury to this center may lead to center respiratory failure, which necessitates mechanical ventilation; usually the prognosis is grave.
In healthy individuals the presence of elevated carbon dioxide levels in the blood is the stimulant that the RC responds to in order to signal the respiratory muscles to breathe. Chemoreceptors found in carotid bodies and aortic bodies are responsible for detecting decrease in blood pH by this carbon dioxide.
Respiratory center is divided into four major cliques
Inspiratory center (Dorsal respiratory group)
- Location: Dorsal portion of medulla
- Nucleus: Nucleus tractus solitarius
Expiratory center (Ventral respiratory group)
- Location: Antero- lateral part of medulla, about 5 mm anterior and lateral to dorsal respiratory group
- Nucleus: Nucleus ambiguous and nucleus retro ambiguous.
- Function: It generally causes expiration but can cause either expiration or inspiration depending upon which neuron in the group is stimulated. It sends inhibitory impulse to the apneustic center.
- Location: Pons(upper part )
- Nucleus: Nucleus parabrachialis
- Function: It controls both rate and pattern of breathing. Limit inspiration.
- Location: Pons(lower part)
- It discharges stimulatory impulse to the inspiratory center causing inspiration.
- It receives inhibitory impulse from pneumotaxic center and from stretch receptor of lung.
- It discharges inhibitory impulse to expiratory center.
Respiratory center depression
Depression of a respiratory center can be a result of the following reasons:
- medical drug action (μ-opioids, sedatives, etc.)
- sudden cessation of blood circulation in brain
- heavy brain trauma
- brain tumors
- damage of a brainstem
Respiratory center stimulation
Amphetamine stimulates the medullary respiratory centers, producing faster and deeper breaths. In a normal person at therapeutic doses, this effect is usually not noticeable, but when respiration is already compromised, it may be evident.
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