ﺑﺎﺯﮔﺸﺖ ﺑﻪ ﺻﻔﺤﻪ ﻗﺒﻠﯽ
خرید پکیج
تعداد آیتم قابل مشاهده باقیمانده : 3 مورد
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Efferent and afferent signals that contribute to the sensation of dyspnea

Efferent and afferent signals that contribute to the sensation of dyspnea
The symptom of dyspnea likely arises from a range of sensory inputs, many of which lead to qualitatively distinct descriptive phrases used by patients. The sensation of respiratory effort arises from signals transmitted from the motor cortex to the sensory cortex (green arrow) when outgoing motor commands are sent to the ventilatory muscles (blue arrow). Motor output from the brain stem (blue arrow) may also be accompanied by signals transmitted to the sensory cortex, contributing to the sensation of effort (dotted green arrow).
The sensation of air hunger probably derives from a combination of stimuli that increase the drive to breathe such as insufficient oxygen or excess carbon dioxide (mediated by signals from chemoreceptors in the carotid body and aortic arch), acute hypercapnia or acidemia (mediated by signals from the peripheral and central chemoreceptors), airway and interstitial inflammation (mediated by pulmonary afferents), and vascular receptors. The intensity of air hunger is increased when there is a perceived mismatch between the outgoing efferent messages to the ventilatory muscles and incoming afferent signals from the lungs and chest wall.
Chest tightness, commonly associated with bronchospasm, is mediated by stimulation of vagal-irritant receptors. Afferent signals (red arrows) from airway, lung, and chest wall receptors most likely pass through the brain stem before being transmitted to sensory cortex, although it is also possible that some afferent information bypasses the brain stem and goes directly to sensory cortex (dotted arrow).
Red arrows: afferent signals; Blue arrows: efferent signals; Green arrows: signals within the central nervous system; Dotted lines: hypothetical pathways; Circles: chemoreceptors; Squares: mechanoreceptors.
Graphic 69322 Version 5.0

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