Pneumotaxic Centre

The pneumotaxic centre’s primary function is to control the ‘switch off’ point present in the inspiratory ramp, which usually boosts or helps it to control the duration of the filling phase of the lung cycle. The inspiration process may last for as low as 0.5 seconds when the pneumotaxic signal is strong (filling the slight parts of the lungs). 

However, the inspiration process might also continue or last for 5 or more seconds when the pneumotaxic signal is weaker, which helps in filling the lungs with a much greater quantity of air. The function of the pneumotaxic centre may vary primarily to even limit inspiration, which shows a secondary effect of increasing or boosting up the rate of breathing due to limitation of inspiration also helps in shortening expiration and the entire period of each particular respiration. 

The rate of breathing can increase up to 30 to 40 breaths/min due to a strong pneumotaxic signal, vice versa weak pneumotaxic signal may reduce the rate to only 3 to 5 breaths/min. Our Respiratory centre is even modulated by the pneumotaxic centre, which helps in limiting the length or the duration of the inspiratory signal and also has a great influence on the RR and apneustic centre located in the pons.

Location of Pneumotaxic centre

The pneumotaxic centre is located in the upper pons which helps in sending inhibitory impulses to the inspiratory centre, stopping the process of inspiration, and thereby maintaining and regulating the inspiratory volume and respiratory rate. This pneumotaxic centre mainly is involved in the fine-tuning of breathing. Under voluntary control of our body; breathing plays a major role. 

The cerebral cortex is capable of overriding various impulses from mainly the brainstem in numerous situations for example coughing and sniffing. These voluntary actions are only limited by sudden visible changes in arterial blood gas tensions. However, In addition to these uncoerced changes in respiration, there is an interference in the suprapontine reflex with respiration which can occur during coughing, sneezing, and even swallowing.

 that project from the brainstem, cerebral cortex, and other suprapontine structures descend along with the anterolateral white matter of the spinal cord to the phrenic, intercostal, and abdominal muscle motor neurons in the axons. When these effector’s muscles are stimulated they lead to the complete generation of a breath. 

The decreasing automatic pathways are most likely tens to lie in the formation of the paramedian reticular of the medullary and also the pontine tegmentum and the high cervical cord at a close distance to the spinothalamic tract, whereas the decreasing pathways of the voluntary system are mainly analogous with the corticospinal tracts present in the brainstem and also in the upper cervical cord. 

The mediating inspiration of the nerve fibres connects to the phrenic motor neurons located in the ventral horns from C3 to C5 and also the intercostal motor neurons present outside in the ventral horns throughout the thoracic spinal cord, typically from T2 to T12. The fibres are solely responsible for the active expiration connection primarily on the internal intercostal motor neurons in the thoracic spinal cord. 

The site of origin for automatic impulses that control breathing is the brain stem. The ventilatory pattern generation mainly involves the combination of several neural signals from three main groups of neurons located basically in the medulla (in the respiratory control centres) and pons: those three main groups are (the medullary respiratory centre, the apneustic centre, and the pneumotaxic centre).

Functions of pneumotaxic centre

To explain the function of the pneumotaxic centre precisely we can say that respiration usually begins with taking a breath and filling the lungs with the inhaled air. The automatic process of breathing is normal quiet breathing that starts with a signal created from those three pairs of respiratory centres located inside the brainstem including the pons and medulla. 

A pneumotaxic centre located in the pons usually in between inspiratory and expiratory signals acts as a switch which is generated by the inspiratory known as the dorsal respiratory group and also the expiratory known as the ventral respiratory group which helps in sending signals around the centres located in the medulla. Nerve fibres emerging from these signalling centres then connect with other nerve fibres that reach the respiratory muscles through direct supply.

By the process of contractions of a group of inspiratory muscles, chief among them being the diaphragm, inspiration is accomplished. When the dome-shaped muscle called the diaphragm separates the thoracic from the abdominal cavities it eventually contracts, the dome gets straight in a position toward the abdomen, thereby raising the volume concentration of the thoracic cavity. 

At the same time, the pneumotaxic centre of the pons, the upper external intercostal muscles, rises along the ribs, leading to an increase in the size of the chest cavity. The lungs on their own follow the contours through the expanding chest wall because of the created negative pressure between the outer layer called the visceral pleura of the lungs and the inner layer called parietal pleura lining the chest wall. 

Pneumotaxic centre points

• The plexus or ganglion providing off nerves that control a function is the point from which the whole process starts.
• The pneumotaxic centre is also a known nerve centre.
• Accelerating the centre (vasomotor centre) located in the brainstem is also involved in the acceleration of actions carried out by the heart.
• A nerve centre present in the brainstem responsible for the control of normal respiration is known as the apneustic centre.

Conclusion

Pneumotaxic centre meaning simply defines the centre present in the pons that rhythmically allows inspiration. The respiratory frequency only reveals a glimpse of any complete clinical picture. The more indicative of other respiratory physiology are mainly the pattern, effort, and volume of respiration. 

Any abnormality seen in Respiration might be a primary problem or any embodiment of other various systemic diseases. The process that plays a critical role in determining the overall assessment of illness in any individual is the respiratory status of both adults and children. 

Like the pneumotaxic centre, Apneusis is also known as the prominent end-inspiratory pauses that can be formed by the pontine transactions in animals who are vagotomised.