 This video will cover the following objective from cardiovascular physiology part two blood vessels Describe the role of the baroreceptor reflex in regulating blood pressure the bororeceptors are Sensory receptors located within the large arteries of the aortic arch and the carotid sinus these receptors are monitoring the mean arterial pressure and relaying that information in to the cardiovascular control centers in the medulla oblong gata This slide summarizes the baroreceptor reflex arc in response to a low mean arterial pressure when this decrease in pressure is detected by the baroreceptors in the carotid sinus and the aortic arch This will lead to decreased frequency of action potentials in the visceral sensory fibers The a ferrite pathway Which is the visceral sensory fibers found in cranial nerves 9 and cranial nerve 10 cranial nerve 9 is the glossopharyngeal nerve traveling from the carotid sinus Whereas cranial nerve number 10 carries the sensory fibers Coming from the arch of the aorta cranial nerve 10 is known as the vagus nerve And so in the illustration I just focused on showing the vagus nerve traveling from the arch of the aorta, but the glossopharyngeal nerve would also be carrying this a ferrite pathway just coming from the carotid sinus So the decreased frequency of action potentials in these a ferrite fibers is relaying the information into the control center in the medulla oblong gata and then the medulla oblong gata stimulates the sympathetic nervous system as an a ferrite pathway the sympathetic Nervous system will stimulate the heart and stimulate the arterioles the effector organs in order to produce a response Increasing the mean arterial pressure to restore the homeostatic set point The heart will increase heart rate and stroke volume leading to increased cardiac output at the same time the systemic arterioles can can have vasoconstriction in order to stimulate and increase total peripheral resistance Information from the borrower receptors is used to regulate the mean arterial pressure When the cardiovascular control centers detect the Change in the mean arterial pressure from the homeostatic set point They can trigger compensatory responses In the example here we see the borrower receptor reflects mechanism in response to a Decrease in blood pressure when the borrower receptors of the carotid sinus and aortic arch detect a Decrease in the mean arterial pressure That is going to cause a decrease in the firing rate of action potentials of those a ferrite fibers in the Glossopharyngeal and vegas nerves that relays this information into the cardiovascular control centers of the medulla oblongata and leads to a decreased activity of the cardiac inhibitory center which regulates the parasympathetic fibers controlling heart rate and Increase activity of the cardiac accelerator centers that Stimulate the sympathetic efferent fibers that regulate cardiac output and this also increases activity in the vasomotor center which stimulates the sympathetic efferent fibers traveling to the Blood vessels to the small blood vessels called arterioles and so a decrease in mean arterial pressure is being processed by the cardiovascular control centers in the medulla oblongata and Leads to increased sympathetic nervous system activity and That increased sympathetic nervous system activity increases the heart rate and the stroke volume and also Causes vasoconstriction increasing the vascular resistance or the total peripheral resistance the resistance to blood flow through the vessels These mechanisms work together to restore blood pressure increasing the mean arterial pressure back to the homeostatic set point in response to increased stretching of the carotid sinus detected by the baroreceptors and increased frequency of action potentials is relayed in through the afferent pathway found in the Glossopharyngeal and vegas nerves that carry information into the medulla oblongata the control center that will then stimulate the parasympathetic efferent pathway Which also travels out through the vegas nerve carrying the Information down to the heart where the post ganglionic Parasympathetic fibers will release acetylcholine in the SA node and AV node leading to a decreased heart rate Decreasing heart rate then Contributes to a decrease in cardiac output that helps to lower the mean arterial pressure and restore the homeostatic set point In response to an increased mean arterial pressure Detected by the baroreceptors as increased stretching of the aortic arch and carotid sinus The visceral afferent fibers will have an increased frequency of action potentials and relay the information into the medulla oblongata to stimulate the cardiac inhibitory center that will activate the parasympathetic division of the autonomic nervous system Stimulate the release of acetylcholine in the SA node and AV node of the heart Which has the effect of decreasing the heart rate? And this is the primary way that the parasympathetic nervous system can Cause a decrease in the blood pressure to help maintain homeostasis of the mean arterial pressure although at the same time in response to increased blood pressure The cardiac accelerator centers and vasomotor vasomotor centers will have decreased activity leading to decreased sympathetic nervous system activity which also will contribute to a decrease in cardiac output and an Increase in vasodilation which decreases the total peripheral resistance