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Does caffeine affect heart rate

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Does Caffeine Affect heart rate? By James Banham 11/28/2008 Does caffeine affect heart-rate? In this investigation I intend to find out if caffeine has an affect on heart rate. As an alternative to using human subject, who might previously have had a high tolerance to caffeine or possibly will have taken a dose of caffeine that day making the tests unfair, instead I will use Daphnia, a crustacean. They have no contact with caffeine making it fair. It will be simpler to examine as it has a translucent body, making it able to see the heart beating under a microscope. I will be making this a "blind study" to avoid bias results, so I will be oblivious to what the solution consists of. To make this experiment accurate and reliable, I will be using graphs and tables to show information about my results; I will use the graphs to compare the results with the control. I will also include a write up about the procedure of the experiment. Caffeine Caffeine acts as a stimulant drug in humans and other animals. ...read more.


I will then remove the excess water using the filter paper, and then I will add a few drops of either pond or distilled water. I must be careful not to have too little water otherwise the daphnia will be limited of oxygen. 2) I will use a stopwatch to record the heart-rate of the daphnia, as I will be working in a pair I will get one of us to count the beats and the other to time. I will record the heart rate at interval of 2 minutes over a 10 minute period; the first result will be our control. As I am doing a blind study, the one of us who is counting the heart-rate will be unaware of whether the water is plain or contains caffeine. 3) I will repeat the procedure using other daphnia from the culture solution and clean cavity slides. Instead of using water I will now replace it with the 1% caffeine solution. I will now repeat this process using the different concentrations of caffeine. 4) I will record my results in a sensible table and use a graph to compare the results with the control. ...read more.


Also the results would not have been accurate or reliable because the daphnia would not have had enough time to shake off the previous dose of caffeine. To make the results valid, i needed to trial various daphnia to ensure I had varying results and no outliers. Conclusion My hypothesis was that as the caffeine increases, the heart rate of the daphnia will also. The results I obtained indicate that my theory was accurate this is because as the different types of caffeine solutions are added the heart rate increased. Although the results of this experiment are accurate, I speculate whether the temperature of the surroundings played a part in the daphnia's heart rate, as daphnia are dependable on temperature to survive. I also consider that alcohol, a depressant, could possible lower their heart rate. If I were to conduct this investigation again I would like to use a larger range of caffeine solutions, as I believe this would give precise results. Also I would like to use a thermometer to measure whether temperature does have an effect on the daphnia. ...read more.

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