Does Caffeine Affect the Heart Rate of Daphnia

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Does Caffeine Affect the Heart Rate of Daphnia? Introduction This experiment deals with the affects of caffeine on the heart rate of daphnia. The following includes information about daphnia and caffeine. Daphnia, also commonly called water fleas are small aquatic crustaceans. They are about 0.3 mm long which is about the size of this dot ( . ) . They are freshwater zooplankton and consume phytoplankton (photosynthetic protists). Some daphnia are, however, carnivorous, eating other zooplankton. The body of a daphnia are laterally compressed. That is, they are flat. There bodies are divided into three parts, similar to an insect. The part I will be concentrating on is the heart. The heart of a daphnia is rather conspicuous (large). It is easily seen while viewing the crustacean under a microscope. Because the heart is so large and its beating can be easily counted, daphnia are commonly used in a variety of physiological experiments including response to temperature changes and responses to stimulants and depressants. The effects of caffeine are important to consider because something like 90% of Americans consume caffeine in one form or another every single day. About half of all Americans consume more than 300 mg of caffeine a day, making it America’s most popular drug. Caffeine is found in consumables like coffee, tea, cola, chocolate, etc. Caffeine medically known as trimethylzanthine. Its chemical formula is C8H10N4O2. When in pure form, caffeine is a white crystalline powder that taste very bitter. The most common way of acquiring pure caffeine is the process of decaffeinating coffee and tea. Caffeine is useful as a cardiac stimulant and also as a mild diuretic. Cardiac stimulants increase the heart rate, and diuretics increase urine production. Caffeine is also used to provide a “boost of energy” or a feeling of heightened alertness. Caffeine is an

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