To investigate the effect on caffeine on heart rate of water fleas and to understand the risk of high level consumption of caffeine to the health of the human circulatory system and nervous system.
Diagram 1: Chemical structure of caffeine
Image source: http://ismaastricht.wikispaces.com/file/list
The images above show the chemical structure of caffeine which has a chemical formula of C8H10N4O2. Caffeine was named by the International Union of Pure and Applied Chemistry (IUPAC) as 1,3,7-trimethyl-1H-purine-2, 6(3H, 7H)-dione. Caffeine is also widely known by several other chemical names which include 1,3,7-trimethylxanthine, trimethylxanthine, methyltheobromine, 7-methyltheophylline, theine, mateine, and guaranine. Caffeine is identified as a bitter, odourless, white crystalline xanthine alkaloid which is a psychoactive stimulant drug. Caffeine is found in the beans, leaves and fruits of some plant in various quantities. It is most commonly found in the beans of coffee plants and leaves of tea bush. Caffeine was originally used as natural pesticide that paralyses and kills certain insects feeding on the plants. However, scientists have discovered that caffeine causes an effect on the central nervous system (CNS) whereby it acts as a stimulant in the human body.
Diagram 2: Source of caffeine from the extraction of coffee beans Image source: http://www.sciencedaily.com/releases/2009/01/090113203901.htm
Caffeine is considered as a drug that stimulates the body and causes an increased amount of stimulatory neurotransmitter to be released. This temporarily reduces the sensation of being tired throughout the day and increases alertness. At high level of caffeine consumption, it can and has been linked to restlessness, anxiety and insomnia which can cause raised stress and blood pressure and thus, leading to hypertension. This will then lead to a more severe health problem such as cardiovascular disease (CVD). The following diagram shows other common side effects of caffeine, possibly
appearing at a lower dosage varying to different individuals.
Diagram 3: Side effects of caffeine
Image source: http://crossfitoneworld.typepad.com/crossfit_one_world/2009/07/coffee-needed.html Caffeine is now a common ingredient of soft drinks such as cola, originally prepared from kola nuts. Research which was carried out shows that soft drinks typically contain about 10 to 15 milligrams of caffeine per serving. Besides, chocolate bars have a high percentage of caffeine content especially in dark chocolate. Those are some examples of foods and beverages we consume almost every day which contain high caffeine content. Hence, this experiment is conducted to determine effect of caffeine on the human heart rate. To determine the effect of caffeine in human heart, a suitable substitute of human being is used to carry out this experiment. The most suitable organism to act as the substitute to human is identified as Daphnia sp. which is a water flea. Daphnia are small, planktonic crustacean which the size ranges between 0.2 to 5mm