The respiratory center is that part of the brain that controls both inhalation and exhalation. It is located in the medulla oblongata and consists of four subunits. Dysfunction of the respiratory center may occur as a result of neurologic diseases, lesions, and poisoning, among other conditions, or may be associated with other diseases.
What is the respiratory center?
The respiratory center is a functional unit in the brain located in the medulla oblongata, the medulla oblongata. Because of its enormous importance, physicians originally referred to the respiratory center as the vital node (nodus vitalis). Its function is to control breathing, which is essentially involuntary; however, humans are able to control inhalation and exhalation – to some extent – consciously. In 1811, French physician and physiologist Julien Jean Legallois was the first to describe this part of the brain. Like many brain functions, the respiratory center was discovered by comparing healthy and damaged tissue. Legallois found, with the help of animal experiments, that lesions in a specific area of the medulla oblongata lead to inhibition of involuntary breathing.
Anatomy and structure
The respiratory center is located in the medulla oblongata and is not a single anatomic structure. Instead, it is a functional unit composed of different neurons. These belong to different groups, but are closely interconnected via synapses. Medicine distinguishes four subgroups: The dorsal respiratory group, the ventral respiratory group, the pneumotactic center, and the apneustic center. Different units represent different functions and tasks. The dorsal respiratory group extends longitudinally through the medulla oblongata, with most neurons located in the tractus solitarius. This group is a network with no fixed boundaries. The ventral respiratory group surrounds the dorsal respiratory group laterally and in the thoracic direction; again, however, these are not clearly delineated structures. Both the pneumotaxic center and the apneustic center are located in the bridge (pons): the latter is in the lower part, whereas the pneumotaxic center is located above it.
Function and tasks
Involuntary inhalation and exhalation depend on the respiratory center; functionally, four steps in the respiratory process can be distinguished. The different groups of neurons within the respiratory center each perform only specific functions. Dorsal respiratory group is mainly responsible for the rhythm of breathing. Inhalation, with a duration of about two seconds, is shorter than exhalation, which lasts about 3 seconds. For inspiration, the dorsal respiratory group sends signals to the respiratory muscles, which then actively facilitate inhalation. For passive exhalation, the respiratory center does not need to generate its own signal. In contrast, the ventral respiratory group of the respiratory center is necessary for forced breathing, which can accelerate or force both inhalation and exhalation. The pneumotactic center in the pons controls a part of the respiratory process that many people are not consciously aware of: It stops inhalation, helping to control the maximum volume of air in the lungs. Apneusis is the medical term for the counterpart of this process: the apneustic center of the respiratory center causes brief violent inhalations, as in gasping breaths. After prolonged holding of breath, great exertion or in other stressful situations, apneusis in this way helps to ensure the body’s oxygen supply.
Diseases
One of the most well-known respiratory disorders is hyperventilation, in which sufferers inhale and exhale rapidly. As a result, symptoms may include dizziness, visual disturbances, feelings of suffocation, sensations of panic, and cardiovascular symptoms. Hyperventilation can occur as part of both physical and psychological symptoms, with physical causes including acutely increased oxygen demand and conditions such as stroke (apoplexy), traumatic brain injury, encephalitis, and other cerebral incidents. Hyperventilation as a psychological symptom is particularly characteristic of panic and anxiety attacks.Patients with depression or pain disorders are also more prone to hyperventilation than other individuals. Dyspnea is a severe respiratory disorder that can be fatal if untreated and is characterized by a reduced number of breaths, with affected individuals taking in only a small amount of air into the lungs per breath. Dyspnea naturally often occurs before death and pathologically may precede complete respiratory arrest. In respiratory arrest, breathing stops completely but may resume under some circumstances; the specific cause is the most important factor. Possible causes of respiratory arrest include neurologic disease, poisoning, paralysis of the respiratory muscles, certain external forces such as strangulation, medical trauma, electrical accidents, and anesthetic complications. Temporary cessation of breathing for at least 10 seconds during sleep characterizes sleep apnea or sleep apnea syndrome. Other potential symptoms include restless sleep, increased night sweats, increased urination during sleep (nocturia), difficulty sleeping through the night, and episodes of microsleep. Upon awakening, dizziness and headaches may occur. In addition, sleep apnea often manifests in signs that affect mental performance, for example, concentration problems and depressed mood. Drug use, obesity (adiposity), and neuronal diseases are among the most common causes. Treatment varies depending on the cause, but is urgently needed, especially in severe cases, to prevent secondary physical damage from oxygen deficiency. Other breathing disorders include respiratory sounds (stridor), dragging breathing, periodic breathing, mouth breathing, hiccups (singultus), and sneezing.
