BIOL 221 Lecture Notes - Lecture 7: Peripheral Chemoreceptors, Central Chemoreceptors, Medulla Oblongata
3 Mar 2020
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Document Summary
Chemoreceptor reflexes are based on responses to changes in systemic arterial carbon dioxide, oxygen and ph (hydrogen ion) levels. Central chemoreceptors are located in the medulla oblongata and monitor the cerebrospinal fluid of the fourth ventricle. These chemoreceptors synapse directly with neurons in the medullary respiratory centers. Peripheral chemoreceptors are located in the aortic and carotid bodies and are the same ones that are involved in blood vessel and cardiac responses to blood gas and blood ph changes. Afferent neurons run through the vagus and glossopharyngeal nerves. Central chemoreceptors are sensitive to carbon dioxide. This is the most important factor in determining rate and depth of breathing. The effect of carbon dioxide in stimulating breathing is independent of arterial oxygen and ph levels. Carbon dioxide diffuses across the blood-brain and blood-csf barriers into the cerebrospinal fluid of the fourth ventricle. Once in the csf it reacts with water to form carbonic acid (h2co3).
