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|Brain: Dorsal respiratory group|
|Section of the medulla oblongata at about the middle of the olive. (Dorsal respiratory group not labeled, but spinal tract labeled at center right.)|
The DRG is involved in the generation of respiratory rhythm, and is primarily responsible for the generation of inspiration. It is a part of the solitary tract, which is responsible for appropriating responses to sensory information from chemoreceptors and mechanoreceptors in humans.
Inspiration begins when cells of the solitary tract nucleus (along with cells of the ventral respiratory group) begin a steady increase in firing, leading to contraction of the respiratory muscles. When neurons in the DRG fire, impulses travel down the phrenic and intercostal nerves to stimulate the diaphragm and external intercostal muscles. The thoracic cavity expands and air rushes into the lungs due to the negative pressure, producing inspiration. When the cells stop firing, the inspiratory muscles relax, inspiration ceases, and exhalation begins.
The rhythm of the DRG produces a respiratory rate of 12-16 breaths per minute in humans. Inspiration usually lasts approximately 2 seconds, and expiration lasts about 3 seconds. The normal inspiration rate and rhythm is called eupnea, and difficult respiration is termed dyspnea.
Berne, Robert M.; Levy, Matthew N.;Koeppen, Bruce M.;Stanton, Bruce A. (2004). Physiology, 5th edition, 513, St. Louis, MO: Elsevier.
Respiratory system, physiology: respiratory physiology
lung volumes - vital capacity - functional residual capacity - respiratory minute volume - closing capacity - dead space - spirometry - body plethysmography - peak flow meter - thoracic independent volume - bronchial challenge test
ventilation/perfusion ratio (V/Q) and scan - zones of the lung - gas exchange - pulmonary gas pressures - alveolar gas equation - hemoglobin - oxygen-haemoglobin dissociation curve (2,3-DPG, Bohr effect, Haldane effect) - carbonic anhydrase (chloride shift) - oxyhemoglobin - respiratory quotient - arterial blood gas - diffusion capacity - Dlco
|Control of respiration|
Brain: rhombencephalon (hindbrain)
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