Topics: Heart rate, Nervous system, Towel Pages: 1 (401 words) Published: January 14, 2013
Does caffeine affect heart rate?
In this experiment we were examining the effect of caffeine on the heart rate of Daphnia which are water fleas. In my opinion I think that the caffeine will affect the heart rate because when the caffeine enters your blood from the stomach and small intestine it begins to stimulate your central nervous system, the Caffeine stimulates receptors in the cells of your heart to increase your heart rate. The increase of this heart rate speeds up your blood flow as well as increase in blood sugar, urination and blood sugar. So, considering that you can see the through the transparent fleas after dropping the caffeine on them you will witness the hearts beat as a greater haste than usual. So, I will experiment this hypothesis by placing Daphnia under a microscope and recording the heartbeats before pouring the caffeine and after pouring the caffeine. The apparatus used involved culture of Daphnia, cotton wool, cavity slides, dropping pipettes, distilled water, caffeine, beakers, stopcock, paper towels and a microscope. Before starting the experiment we had to set up the microscope. We then had to catch the Daphnia with a plastic pipette and place them on a cavity slide which would have a small amount of cotton wool on it to stop the Daphnia from moving and wipe out the excess water with a paper towel. After the Daphnia is placed on the slide, put the slide in an accurate position in which you can see the Daphnia clearly most importantly its heart. Before adding the Caffeine it was advised that we should record the heart rate beforehand. Then after recording the Daphnia heart rate in pond water we then added 0.5g of Caffeine which was dissolved in water and record its heart rate every two minutes with ten second intervals with a stop clock. The independent variable was the amount of time the Daphnia took to go back to its original heart pace and the dependent variable is the change in heart rates of the daphnia in different amounts of...
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