P3- The drop in pH is detected by the central chemoreceptors in the medulla oblongata
P4- and detected by peripheral chemoreceptors ( carotid bodies and aortic bodies )
P5-The central chemoreceptors and pheripheral receptors send nerve impulses to the respiratory centre in the medulla oblongata
P6- The respiratory centre sends nerve impulses to the diaphragm and the intercostal muscles, causing the respiratory muscle to contract and relax faster
P7- As a result, the breathing and ventilation rate increase causes more oxygen inhaled and the oxygen concentration return to the normal level
P8- As excess carbon dioxide is eliminated from the body, the carbon dioxide concentration and pH value of the blood return to normal level
ii) Explain why the pulse rate takes several minutes to return to normal after a vigorous activity.
P3- As a result, lactic acid accumulates in the muscle.
P4- So more oxygen is needed to oxidize the lactic acid and to provide the energy for the recovery of the muscle