Effects of drugs on pulsation rate (parts 1 & 2)
BIO 10200 Lab Section 2PS2
Regheim Beck
Lab Partner: Nicholas Jairam
11/31/18
Introduction:
In this lab blackworms were used to see how different doses of caffeine, nicotine,
tobacco, cigarettes, and decaf affects the pulsation rate of Lumbriculus variegatus, Blackworms.
These worms live in muddy sedimentary soil, especially in shallow water such as marshes and
ponds throughout the United States, and other places (Lumbriculus variegatus). These worms
were used for the experiment because of they are simple organisms. They do not have a heart or
lungs, and their transparent bodies makes their major blood vessel and the pulsation easy to see
and monitor through a microscope. The blackworms have smooth muscle in their back that
contracts and moves blood from their posterior (tail) to their anterior (head). They can grow
about 2-8 centimeters in length.
Nicotine can be both a sedative and a stimulant depending on the dose. Nicotine
stimulates the adrenal glands, which results in the release of adrenaline. When exposed to
nicotine, it increases heart rate, heart muscle oxygen consumption rate, and heart stroke volume
(Weatherspoon, D). Caffeine can increase heart rate, body temperature, blood flow, blood
pressure, and blood sugar levels (Caffeine- University of Michigan). This effect is thought to be
attributed to either an increase in adrenaline or a temporary block on the hormones that naturally
widen your arteries. Caffeine also Stimulates the central nervous system, which gives people the
feeling of being awake and alert. Tobacco has many negative effects on the circulatory system.
It can raise the blood pressure and heart rate, cause tightening of blood vessels, increase risk of
blood clotting, damage to the lining of the arteries, reduced blood flow to the extremities, reduce
lung function due to swelling and narrowing of the lung airways and excess mucus in the lung
passages (Department of Health & Human Services). In the long run tobacco could lead to death
due to the negative effects on the body listed above.
Hypothesis for caffeine: the higher the concentration of caffeine the higher the pulsation
rate of the blackworms. Hypothesis for Nicotine: the pulsation rate of blackworms will decrease
with an increase in nicotine. Justification: the effects caffeine and nicotine have been shown to
have on the human physiology as mentioned above. The null hypothesis for this experiment is
that the treatments will have the opposite effects as hypothesized and have seen to have in
humans.
Methods:
For this experiment three black worms were used for each treatment, two treatments per
group with a total of six worms per group. The worms were studied under a dissecting
microscope in a parafilm slide. Prior to treatment, the pulsation rate of each worm (A,B,CTreatment 1and D,E,F- Treatment 2) was counted in 30 second intervals by observing the tail
end of the worm and counting the times the muscles along the dorsal of the worm contracted. For
each worm this was done a total of three times then the average pulsation rate was calculated.
The worms were then put into a container filled with either treatment 1 or treatment 2 and were
again observed for pulsation rate after being in the treatment solution for 15 minutes. Finally, the
pulsation rate was observed for three times by measuring contractions in 30 second intervals then
the average was taken.
Results:
Figure 1. Change in Pulsation Rate due to Caffeine Treatment
Figure 2. Average Change in Pulsation Rate for Nicotine Treatment
Figure 3. Average Change in Pulsation Rate due to Various Treatments
Figure 4. Change in Pulsation Rate of all Treatments and their Standard Deviations
Table 1. T-Test for Caffeine 1.0mM
Table 2. T-Test for Nicotine 0.05mM
Discussion:
The null hypotheses are rejected and the hypotheses, the pulsation rate might increase
with an increase in the caffeine concentration and decrease with an increase in nicotine
concentration, are supported by the data above. As shown by Figure 1, the average change in rate
of pulsation in the black worms increased drastically from 4.8 to 9 for caffeine 1.0 and mM,
3.0mM respectively, with only a slight decrease in pulsation rate from caffeine 3.0mM to
caffeine 10.0mM treatment. It is also shown in Figure 2 that the the average change in rate of
pulsation in the black worms decreased drastically from from 5.8 to -12.9 for nicotine treatments
0.5mM and 1.0mM. The nicotine treatment acted as a sedative. The t-test showed that the
pulsation rate of the blackworms were noticeably affected by the caffeine and nicotine, as well as
the other treatments used. Note that the black worms under tobacco treatment died which might
shed light on the toxicity of the substance as mentioned above. Possible sources of error could be
the dilution of the treatments when a pipet was used to transfer the worms, or human error in
counting the pulsation rates.
Works Cited
Caffeine. (n.d.). Retrieved from https://www.uhs.umich.edu/caffeine
University Health Service- University of Michigan
Department of Health & Human Services. (2018, January 18). $name. Retrieved from
https://www.betterhealth.vic.gov.au/health/healthyliving/smoking-effects-on-your-body
Lumbriculus variegatus. (n.d.). Retrieved from
https://www.eeob.iastate.edu/faculty/DrewesC/htdocs/Lvfacts.htm
Weatherspoon, D. (2018, January 11). Nicotine: Facts, effects, and addiction. Retrieved from
https://www.medicalnewstoday.com/articles/240820.php