Respiratory center

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The respiratory center (RC) is located in the medulla oblongata, which is the lowermost 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 central 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 and aortic bodies are responsible for detecting this CO₂.

Individuals who suffer from Chronic Obstructive Pulmonary Disease usually have a chronically elevated level of carbon dioxide present in their blood due to their diminished lung function. As a result, their specific chemoreceptors become desensitised to the hypercapnia and instead respond to a decreased amount of oxygen present.

The groups of nerve cells in the brain which regulates the respiration rhythmically are collectively known as respiratory centers.

Groups

Respiratory centre is divided four major groups:

Inspiratory centre (Dorsal respiratory group)

• Location: Dorsal portion of medulla
• Nucleus: Nucleus tractus solitarius
• Function: causes inspiration while stimulated.

Expiratory centre (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 causes either expiration or inspiration depending upon which neuron in the group are stimulated. It sends inhibitory impulse to the apneustic centre.

Pneumotaxic centre

• Location: Pons(upper part )
• Nucleus: Nucleus parabrachialis
• Function: It controls both rate and pattern of breathing. Limit inspiration.

Apneustic centre

• Location: Pons(lower part)

Function:
a)It discharges stimulatory impulse to the inspiratory centre causing inspiration.
b)It receives inhibitory impulse from pneumotaxic centre and from stretch receptor of lung.
c)It discharges inhibitory impulse to expiratory centre.

Respiratory center depression

Depression of a respiratory center can be a result of next reasons:

• medical drug action (opioids, sedatives and etc.)
• sudden cessation of blood circulation in brain
• heavy brain trauma
• sharp neuroinfections
• brain tumors
• damage of a brainstem

See also

• Control of respiration

References

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