As the runner exercises, his chemoreceptors will detect any increase in carbon dioxide levels. Explain how this causes an increase in the runner’s breathing rate

The increased amount of carbon dioxide, given off as a bi product of the working muscles, is detected by the peripheral chemorecptors (located in the aortic arch). These receptors detect changes in Oxygen and Carbon Dioxide concentration in the arterial blood as well as changes in pH. The levelof hydrogen ions within the blood determines the pH as the more ions the lower the pH (higher acidity). These changes allow the respiratory centre (located in the medulla) to send nerve impulses to the external intercostal muscles and the diaphragm instructing them to contract and relax more frequently, thus increasing breathing rate as the performer exercises,