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Nervous Control of Breathing. Control of Breathing Respiratory Center Other aspects. Control of Breathing. Respiratory muscles can be controlled voluntarily Normal breathing is rhythmic and involuntary. Respiratory Center.
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Nervous Control of Breathing Control of Breathing Respiratory Center Other aspects
Control of Breathing • Respiratory muscles can be controlled voluntarily • Normal breathing is rhythmic and involuntary
Respiratory Center • Control by a group of neurons in the brainstem: the respiratory center • Medulla oblongata = “rhythmicity area” • Pons = “pneumotaxic area” • Neurons in the Medulla control the rhythm of breathing • Neurons emit impulses that signal the diaphragm and other inspiratory muscles to contract. Neurons remain inactive while expiration occurs passively • Neurons in the Pons transmit impulses to the medulla continuously and regulate the duration of inspiratory bursts (control of rate)
Transport of CO2 • Blood in capillaries gain CO2 because body tissues contain high PCO2 • The CO2 could be transported • Dissolved in blood (only~7%) • As Carbaminohemoglobin (~23%) • As HCO3- (most important form) • CO2 + H2O H2CO3 w/ aid of carbonic anhydrase • Carbonic acid dissociates: H2CO3 H + HCO3-
Chemoreceptors in the carotid and aortic bodies detect changes in the blood pH
Breath test: Respiratory surfaces are so thin that certain substances other that CO2 may diffuse into the alveolar air and be expelled during breathing A person emotionally upset may hyperventilate (become dizzy, lose consciousness , faint: alkalosis) due to low CO2 conc, and a rise in blood pH CO may combine w/hemoglobin more effectively than O2 Ordinary air contain 0.04% CO2 Air to which additional CO2 is added is used to stimulate the rate and depth of breathing. If a person inhales air containing 4% CO2 the breathing rate usually doubles Other facts about breathing