Effects of Temperature

The frog is poikilothermic and it's internal temperature is one of the factors which governs the rate of biochemical and physiological processes.

In this experiment you will investigate the effects of cooling and warming the heart by pipetting either warmed (40°C) or cold (0°C) Ringer's solution onto the heart. Since changes in heart rate are under control of the sinus venosus it is important to ensure that the test solution is applied to this region.

The points of application of Ringer's solution of different temperatures are indicated at the top of the trace. The ÔcontrolÕ RingerÕs solution is at room temperature (20°C).

Task
You should measure the change in heart rate before and after the application of test Ringer's and compare this to the control (i.e. the normal heartbeat recorded earlier at room temperature (20°C)).

Use the play/pause button to halt the display to enable you to take your measurements more easily.