The Effects of Secondary Plant Compounds on Lumbriculus Variegatus Heart Rate Introduction
Blackworms (Lumbriculus variegatus) were used in this experiment to study the effects of secondary plant compounds, chemical compounds produced by plants that are not part of the general metabolism, on pulse rate. Secondary plant compounds act as defense mechanisms which reduce or eliminate consumption of some plant species or even attract predators. These compounds are not essential to the plant but often benefit the plant by having harmful effects on animals. These deterrents can include toxins, increased volume of urine, or even affect water balance but they include a wide variety of physiological consequences (Dearing et al, 2002).
Lumbriculus have a dorsal blood vessel that pumps blood from the posterior to the anterior, the tail to the head, of the worm using muscle contractions (Halfmann and Crisp, 2011). This peristalsis can be viewed very easily through their thin, transparent skin. Lumbriculus also diffuse moisture through their thin skin so when they are placed in a substance they absorb it through their skin and any effects from the substances immediately take place. These substances can affect the pulsation of the Lumbriculus.
Lumbriculus were tested with two secondary plant compounds, caffeine and nicotine, to determine the effects of these drugs on their pulse rate compared to the control, water. Caffeine often created a diuretic agent from plants which could affect water balance (Dearing et al,2002). When caffeine is consumed it attaches itself to brain cell receptors, which blocks adenosine, a chemical that makes you sleepy. This blocking of adenosine makes you feel more awake and alert. According to Benowitz et al (2002) nicotine is closely related to many cardiovascular diseases, less oxygen flow to the blood, and ultimately affects a person’s health long-term. Since caffeine creates alertness it is thought that when the worms are placed...
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