The respiratory center is located in the medulla oblongata and pons, in the brainstem. The respiratory center is made up of three major respiratory groups of neurons, two in the medulla and one in the pons. In the medulla they are the dorsal respiratory group, and the ventral respiratory group. In the pons, the pontine respiratory group includes two areas known as the pneumotaxic centre and the apneustic centre.
The respiratory centre is responsible for generating and maintaining the rhythm of respiration, and also of adjusting this in homeostatic response to physiological changes. The respiratory center receives input from chemoreceptors, mechanoreceptors, the cerebral cortex, and the hypothalamus in order to regulate the rate and depth of breathing. Input is stimulated by altered levels of oxygen, carbon dioxide, and pH, by hormonal changes relating to stress, and anxiety from the hypothalamus, and also by signals from the cerebral cortex to give a conscious control of respiration.
Injury to respiratory groups can cause various breathing disorders that may require mechanical ventilation, and is usually associated with a poor prognosis.
Video Respiratory center
Respiratory groups
The respiratory centre is divided into three major groups, two in the medulla and one in the pons. The two groups in the medulla are the dorsal respiratory group and the ventral respiratory group. In the pons, the pontine respiratory group is made up of two areas - the pneumotaxic centre and the apneustic centre. The dorsal and ventral medullary groups control the basic rhythm of respiration.
Dorsal respiratory group
In the medulla, the dorsal respiratory group makes up the inhalation area of respiratory control.
- Location: Dorsal portion of medulla
- Nucleus: Solitary nucleus
Ventral respiratory group
In the medulla, the ventral respiratory group make up the exhalation area of respiratory control.
- Location: Antero-lateral part of medulla, about 5 mm anterior and lateral to dorsal respiratory group
- Nucleus: Nucleus ambiguus and nucleus retro ambiguus.
- 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.
Pontine respiratory group
In the pons, the pontine respiratory group includes the pneumotaxic and apneustic centers. These have connections between them and from both to the solitary nucleus.
Pneumotaxic center
- Location: Upper part of pons
- Nuclei: Subparabrachial nucleus and the medial parabrachial nucleus of the parabrachial area.
- Function: It controls both rate and pattern of breathing. Limit inspiration.
Apneustic center
- Location: Pons (lower part)
- Functions:
- 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.
Maps Respiratory center
Respiratory rhythm
Breathing is the repetitive process of bringing air into the lungs and taking waste products out. The oxygen brought in from the air is a constant, on-going need of an organism to maintain life. This need is still there during sleep so that the functioning of this process has to be automatic and be part of the autonomic nervous system. The in-breath is followed by the out-breath, giving the respiratory cycle of inhalation and exhalation. The number of cycles per minute is the respiratory rate. The respiratory rate is set in the respiratory center by the dorsal respiratory group, in the medulla, and these neurons are mostly concentrated in the solitary nucleus that extends the length of the medulla.
The basic rhythm of respiration is that of quiet, restful breathing known as eupnea. Quiet breathing only requires the activity of the dorsal group which activates the diaphragm, and the external intercostal muscles. Exhalation is passive and relies on the elastic recoil of the lungs. When the metabolic need for oxygen increases, inspiration becomes more forceful and the neurons in the ventral group are activated to bring about forceful exhalation.
Clinical significance
Depression of the respiratory centre can be caused by: brain trauma, brain damage, a brain tumour, or ischemia. A depression can also be caused by drugs including opioids, and sedatives.
The respiratory centre can be stimulated by amphetamine, to produce faster and deeper breaths. Normally at therapeutic doses, this effect is not noticeable, but may be evident when respiration is already compromised.
See also
- Control of respiration
- Cough center
- Gag reflex
- Pre-Bötzinger complex
References
Source of article : Wikipedia
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