Since the earliest days of medicine heart rate has been recognized as a vital sign—an indicator of health, disease, excitement, and stress. Medical personnel use the heart rate to provide clues as to the presence of many medical conditions. Reflex changes in heart rate are one of the body’s most basic mechanisms for maintaining proper perfusion to the brain and other tissues. Low blood volume caused by bleeding or dehydration results in the heart beating faster as it attempts to maintain adequate blood pressure. Excitement, stress, and anxiety activate the nervous system, which may also speed the heart rate and raise blood pressure.


In this experiment, you will

  • Obtain graphical representation of heart rate and blood pressure.
  • Compare heart rate and blood pressure before and after exposure to cold stimulus.
  • Observe an example of sympathetic nervous system activation (“fight or flight response”).