Paroxysmal nocturnal dyspnea bronchi11/28/2023 ![]() Carbon dioxide is a soluble lipid molecule that freely diffuses across the blood-brain barrier. The pH change within the brain and surrounding cerebrospinal fluid is derived primarily by increases or decreases in carbon dioxide levels. Primary locations within the brain include the ventral surface of the medulla, and the retrotrapezoid nucleus. They function through sensing pH changes within the CNS. It has been estimated that the carotid bodies comprise of 15% the total driving force of respiration.Ĭentral chemoreceptors hold the majority of control over respiratory drive. Once stimulated by hypoxia, they send a signal via cranial nerve IX (the glossopharyngeal nerve) to the nucleus tractus solatarius in the brain which, in turn, stimulates excitatory neurons to increase ventilation. The carotid bodies are located at the bifurcation of the common carotid arteries, and the aortic bodies are located within the aortic arch. However, hypercapnia and acidosis increase the sensitivity of these sensors, thus playing a partial role in the receptor’s function. ![]() Both sites function to monitor the partial pressure of arterial oxygen in the blood. ![]() Peripheral chemoreceptors consist of the carotid and the aortic bodies. Both types of mechanoreceptors signal via cranial nerve X (the vagus nerve) to the brain to increase the rate of breathing, the volume of breathing, or to stimulate errant coughing patterns of breathing secondary to irritants in the airway. However, the rapid-acting receptors respond to both volumes of the lung information and chemical irritation triggers such as harmful foreign agents that may be present. Slow-acting spindle sensors convey only volume information. There are 2 primary types of thoracic sensors: slow adapting stretch spindles and rapid adapting irritant receptors. Mechanoreceptors located in the airways, trachea, lung, and pulmonary vessels exist to provide sensory information to the respiratory center of the brain regarding the volume of the lung space. Each of these groups communicates the another to work together for pacemaking potential of respiration. The dorsal medulla is responsible for inhalation the ventral medulla is responsible for exhalation the pontine groupings are responsible for modulating the intensity and frequency of the medullary signals where the pneumotaxic groups limit inhalation and the apneustic centers prolong and encourage inhalation. The pontine grouping further classifies into the pneumotaxic and apneustic centers. The respiratory center of the brain is comprised of 3 neuron groupings in the brain: the dorsal and ventral medullary groups and the pontine grouping. ![]() It results from multiple interactions of signals and receptors in the CNS, peripheral receptors chemoreceptors, and mechanoreceptors in the upper airway, lungs, and chest wall. ĭyspnea is a sensation of running out of the air and of not being able to breathe fast enough or deeply enough. Other systemic illnesses may include anemia, acute renal failure, metabolic acidosis, thyrotoxicosis, cirrhosis of the liver, anaphylaxis, sepsis, angioedema, and epiglottitis. Psychogenic causes may include hyperventilation syndrome, psychogenic dyspnea, vocal cord dysfunction syndrome, and foreign body aspiration. Neuromuscular causes may include chest trauma with fracture or flail chest, massive obesity, kyphoscoliosis, central nervous system (CNS) or spinal cord dysfunction, phrenic nerve paralysis, myopathy, and neuropathy. Respiratory causes may include asthma, acute exacerbation of or chronic congestive obstructive pulmonary disorder (COPD), pneumonia, pulmonary Embolism, lung malignancy, pneumothorax, or aspiration.Ĭardiovascular causes may include congestive heart failure, pulmonary edema, acute coronary syndrome, pericardial tamponade, valvular heart defect, pulmonary hypertension, cardiac arrhythmia, or intracardiac shunting. As such, its etiology can be designated as arising from four primary categories: respiratory, cardiac, neuromuscular, psychogenic, systemic illness, or a combination of these. Dyspnea is a symptom of the disease, rather than a disease itself.
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