All of the following factors increases the level of respiratory neuron activity in the medulla, EXCEPT:
A rise in the PCO2 or H+ concentration of aerial blood or a drop in its Po2 increases the level of respiratory neuron activity in the medulla, and changes in the opposite direction have a slight inhibitory effect. The effects of variations in blood chemistry on ventilation are mediated respiratory chemoreceptors--the carotid and aoic bodies and collections of cells in the medulla. They initiate impulses that stimulate the respiratory center. Stimuli Affecting the Respiratory Center: Chemical control: CO2 ( CSF and brain interstitial fluid H+ concentration) O2& H+ ( carotid and aoic bodies) Nonchemical control: Vagal afferents from receptors in the airways and lungs Afferents from the pons, hypothalamus, and limbic system Afferents from proprioceptors Afferents from baroreceptors: aerial, atrial, ventricular, pulmonary Ref: Barrett K.E., Barman S.M., Boitano S., Brooks H.L. (2012). Chapter 36. Regulation of Respiration. In K.E. Barrett, S.M. Barman, S. Boitano, H.L. Brooks (Eds), Ganong's Review of Medical Physiology, 24e.
Rise in the PCO2
Rise in H+ concentration of aerial blood
Rise in Po2
Drop in Po2