BIOL 221 Lecture Notes - Lecture 2: Bainbridge Reflex, Vagus Nerve, Baroreceptor
11 Feb 2020
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Baroreceptors send afferent impulses via vagus nerve to stimulate cac. When right atrial pressure increases, baroreceptors in the right atrium send more afferent impulses via the vagus nerve to stimulate the cac. The result is increased cardiac sympathetic outflow. Decreased systemic arterial o2 or ph, or increased co2 increases impulses to vasomotor center and cac increased sympathetic outflow. Chemoreceptor reflexes work in much the same way as baroreceptor reflexes except that the sensory receptors are chemoreceptors and the effect is mainly on sympathetic outflow. Chemoreceptors in (called central chemoreceptors) respond mainly to ph (hydrogen ion activity) and carbon dioxide levels (partial pressure of carbon dioxide; pco2). the medulla oblongata. Chemoreceptors in the aorta and carotid arteries also respond to pco2 and ph, and to a lesser extent to oxygen levels (partial pressure of oxygen; po2). The afferent impulses stimulate the cardioacceleratory center and vasomotor center resulting in increased sympathetic outflow. It also decreases parasympathetic outflow to the heart.
