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This experiment studies the effects of common household drugs on circulatory functions, focusing primarily on how it affects pulsation rates in Lumbriculus variegatus. Lumbriculus variegatus is an ideal organism for studying the effect of drugs on the circulatory system due to their transparent bodies and their simple physiology. Their transparent bodies are easily viewed under a microscope and their skin absorbs drug solutions easily.
The circulatory system is a network of organs that are in charge of pumping blood, nutrients, and hormones to the different areas of the body.
Many things can affect the physiology of our bodies, such as common household drugs like caffeine and nicotine. To see the effects of these drugs, the pulsation rate in Lumbriculus variegatus will be observed.
Lumbriculus variegatus, more commonly known as the blackworm, is a species of worm that reside in Northern America and Europe in freshwater. Blackworms have a closed circulatory system, meaning that blood flows inside the blood vessels and does not face direct contact with other organs or tissues.
This lab is divided into two parts; the first part consists of using known concentrations of caffeine and nicotine and observing their effects on the Lumbriculus variegatus’ pulsation rate. The second part consists of using common household drugs such as tea, chewing tobacco, decaff, coffee, and a cigarette to compare the results to the first part.
The different concentrations of caffeine will affect the pulsation rate of Lumbriculus variegatus by increasing it. Caffeine is a stimulant that affects the central nervous system.
It has the ability to counter the effects of inhibitory neurotransmitters. A stimulant usually causes increased heart rate and blood flow, therefore, if caffeine is given to the worms it will increase in relation to the amount of caffeine. (Lab manual, ) The different concentrations of nicotine will influence the pulsation rate of Lumbriculus variegatus by either increasing or decreasing it depending on the concentration. Nicotine is a special type of drug, it acts as a stimulant in high doses while as a depressant in low doses. It mimics the effects of the neurotransmitter, acetylcholine, which increases adrenaline. (Lab manual, )
The different extracts will affect the pulsation rate of Lumbriculus variegatus depending on what type of household drug it is. Coffee, decaffeinated coffee, tea, cigarette, and chewing tobacco are different extracts. Coffee has caffeine, decaffeinated coffee does not have any caffeine, tea has caffeine, cigarettes and chewing tobacco has nicotine. The ones with caffeine should increase the heart rate while the ones with nicotine should decrease the heart rate. The null hypothesis of this experiment is that neither the caffeine nor the nicotine will have an effect on the pulsation rate of Lumbriculus variegatus.
The following materials were used during this lab: Lumbriculus variegatus, dissecting microscopes, stopwatches, 20 mL containers, glass beakers, disposable plastic pipets, springwater, nicotine solutions: 0.05 mM, 0.25 mM, and 1.0 mM, caffeine solutions: 1.0 mM, 3.0 mM, and 10.0 mM, paraffin chambers, applicator stick with a flexible tip, large glass bowls, and household drugs such as coffee, decaffeinated coffee, tea, cigarette, and chewing tobacco.
To conduct the first part of the lab, a pipet was used to retrieve the blackworm and place it onto a parafilm slide to record its basal pulsation rate (rate before treatment) for twenty seconds with the aid of a stopwatch, which will be converted to beats per minute, while under the microscope. Readings shall be taken three times with a thirty-second interval between each reading and then averaged. This is repeated two more times for worm B and worm C. Worm A is then placed in its designated treatment for at least fifteen minutes before getting briefly rinsed with spring water. Pulsation rates are recorded again by following the same steps.
To conduct the second part of the lab, each group was assigned a different solution such as coffee, tea, etc. This sample size consisted of 3 worms per group. Worm A and worm B were tested for part 1 effects of different concentrations of caffeine and nicotine, and worm C was tested for a certain extract.
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