H.6.5+Henry+Lebard

=**H.6.5** **Explain how and why ventilation rate varies with exercise.** When one exercises, ventilation rate increase.= =This is, in part, because when we exercise, we need more oxygen in order to create more energy for the cells (found= =in the muscles involved in exercise). Since more energy is needed, there is a larger intake of oxygen, which allows= =cells undergo cellular respiration, and produce a larger amount of carbon dioxide. This carbon dioxide diffuses into= =the blood, hence increasing the concentration of carbon dioxide flowing through the veins. The carbon dioxide being= =produced causes more carbonic acid to form. This occurs after H2CO3 (carbonic acid) dissociates splitting into= =hydrogen ions and hydrogen carbonate anions. Since more dissociation takes place and more hydrogen ions= =(which can bind to hemoglobin and acidify the blood leading to a lowering of the pH) are produced, the blood attains a= =lower, more acidic, pH.Chemosensors, which are specific regulator cells found in the aorta and carotid arteries made= =to sense changes in chemical levels in the blood, send nerve impulses to the breathing center in the brain.= =The brain then sends nerve impulses to the diaphragm and intercostal muscles causing them to relax or contract more frequently.=