Factors affecting heart rate

• Exercise increases the rate of aerobic respiration
• Carbon dioxide (the waste product of aerobic respiration) will increase in concentration in the blood
• Carbon dioxide increase causes the volume of hydrogen ions in the blood to increase, causing the pH to decrease
• Change in pH is detected by chemioreceptors in the carotid artery
• Sensory neurons carry neural transmissions from the carotid artery to the medulla oblongatus
• Neural transmissions travel along the autonomic nervous system to the sinoatrial node
• The sinoatrial node increases the frequency of its waves of electrical activity
• The sinoatrial node's increase in activity increases the frequency of the atrioventricular node's waves of electrical activity
• The atrioventricular node's increase in activity increases the frequency of ventricle contractions from the base of the septum upwards