OBJECTIVE: To investigate the effect of the caffeine on the heart rate of living organisms.
Daphnia are small, planktonic crustaceans, between 0.2 and 5 mm in length. Daphnia are members of the order Cladocera, and are one of the several small aquatic crustaceans commonly called water fleas because of their saltatory swimming style (although fleas are insects and thus only very distantly related). They live in various aquatic environments ranging from acidic swamps to freshwater lakes, ponds, streams and rivers.In the water flea Daphnia, the single, small heart is easily visible when viewed under transmitted light under a low power microscope. Even under relatively low power microscopy, the feeding mechanism can be observed, with immature young moving in the brood-pouch; moreover, the eye being moved by the ciliary muscles can be seen, as well as bloodcorpuscles being pumped around the circulatory system by the simple heart. The heart is at the top of the back, just behind the head, and the average heart rate is approximately 180 bpm under normal conditions. The heart rate (which can be up to 300 beats per minute) can be monitored and counted in different conditions – for example changing water temperature, or changing the type and concentration of chemicals added to the water. A change in Daphnia heart rate may not be a predictor of a similar change in human (or vertebrate) heart rate under the same conditions, but the procedure provides an interesting technique for investigating the effects of different chemicals on a metabolic process.Daphnia, like many animals, are prone to alcohol intoxication, and make excellent subjects for studying the effects of the depressant on the nervous system – due to the translucent exoskeleton, and the visibly altered heart rate. They are tolerant of being observed live under a cover slip and appear to suffer no harm when returned to open water. This experiment can also be done using caffeine, nicotine or adrenaline and observing an increase in heart rate.
Caffeine is a bitter, white crystalline xanthine alkaloid that acts as a stimulant drug. Caffeine is found in varying quantities in the seeds, leaves, and fruit of some plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding on the plants. It is most commonly consumed by humans in infusions extracted from the bean of the coffee plant and the leaves of the tea bush, as well as from various foods and drinks containing products derived from the kola nut. Other sources include yerba maté, guarana berries, guayusa, and the yaupon holly.In humans, caffeine acts as a central nervous system stimulant, temporarily warding off drowsiness and restoring alertness. It is the world's most widely consumed psychoactive drug, but, unlike many other psychoactive substances, it is legal and unregulated in nearly all parts of the world. Beverages containing caffeine, such as coffee, tea, soft drinks, and energy drinks. It is used therapeutically to relieve headaches, relieve fatigue, and as a diuretic. It can also be found in medications such as migraine and other headache treatments (cafergot, Fiorinal, Fioricet), pain relievers (Anacin, Vanquish, Excedrin, Midol, Darvon, Synalgos-DC, DGA), muscle relaxants (Norgesic, Forte), cold/allergy treatments(Coryban-D), diuretics (Aqua-Ban) and pep pills (No Doz. Vivarin).The route of administration is usually ingestion, swallowed as coffee, tea, cola, soft drink, or as a tablet/capsule medication. It can also be eaten as a chocolate product or ingredient. Sometimes it is injected in sodium benzoate solution.Caffeine induces a slightly elevated mood, alertness, sensitivity of touch, smell, sight, and hearing. It can also cause nervousness, irritability, insomnia, tremors, and depression. The physical effects can include constricted cerebral blood...