Lec19 - Cardiorespiratory Regulation.doc

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Biological Sciences
Mary Olaveson

Cardiorespiratory Regulation1 cardiorespiratory regulationControl of breathingBlood gas transportRegulation of cardiac output and blood pressure2 overview of the control of breathing Breathing is produced in brainstem respiratory centers and is modified by afferent input and central processesTwo schemes for respiratory organ generatorsWithin the heart there is a region that functions as the pacemaker oKeeps our heart beating continuously and rhythmically Within the brain stem there is a region called the prebotzinger complex which functions in the same manner for breathingoIt is much more complex to the heart pacemaker in the sense that there arent simply pacemaker cells Theres a network of neurons that functions together in order to generate a single breathThere are backup control systems for breathingIf one region is failed there are other regions that can take up the taskIn the various regions of the brain a basic rhythm is produced integrated and amalgamated with feedback from a variety of central and peripheral control systems which come together and regulate breathingImportant control systems areoCentral chemoreceptorsRefers to the brainLocated on the ventral surface of the medullaSenses carbon dioxide levels in the spinal fluidoOxygen chemoreceptorsRefers to arterial circulation oReceptors in the aortic arch which senses low levels of blood oxygenoReceptors in the lungs called stretch receptorsAs we breathe in the receptors are stimulated send signal to brain telling it to stop breathingoIrritant receptors which cause us to cough to expel irritantsAll these control systems are amalgamated and ultimately send motor output via the phrenic motor nucleus down to the phrenic nerve to drive our various respiratory organs which happens to be the diaphragm in humans and intercostals muscles between our ribs which contribute to breathingoPhrenic motor nucleusphrenic nerveinspiratory muscles expiratory muscles internal intercostals muscles and others3 central brain control of breathingWithin the brain stem there are four major groupings of respiratory centersoPrebotzinger complex Rhythm generator for breathingFunctions like a pacemakeroPontine respiratory group PRGInspiratory terminationCorrect switching from inspiration to expirationoDorsal respiratory group DRG or NTSSite of first CNS synapse of Carotid sinus baroreceptorsAortic arch baroreceptorsCarotid body oxygen chemoreceptors Pulmonary stretch receptors
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