Blood pressure is a measure of the changing fluid pressure within the circulatory system. It varies from a peak pressure produced by contraction of the left ventricle, to a low pressure, which is maintained by closure of the aortic valve and elastic recoil of the arterial system. The peak pressure is called systole, and the pressure that is maintained even while the left ventricle is relaxing is called diastole.

Mean arterial pressure (MAP) is not a simple average of the two pressures, because the duration of diastole is twice that of systole. MAP is used by emergency room and intensive care unit personnel as a measure of the adequacy of blood supplied to vital tissues (such as the brain, heart, and kidneys) when the blood pressure is dangerously low.


In this experiment, you will

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