acetylcholine
The Effects of Acetylcholine, Epinephrine, and Temperature on the Heart Rate of Daphnia magna Introduction An organism’s heart rate is the number of times per minute that the muscles of the heart contract (Campbell, 1999). ... The purpose of this experiment is to study the effects of acetylcholine, epinephrine, and temperature on the heart rate of Daphnia magna. ... Epinephrine and acetylcholine are neurotransmitters, or substances secreted by neurons that serve as chemical messengers between the cells of the body. Acetylcholine is one of the most common neurotransmitters in both invertebrates and vertebrates. Acetylcholine is released by postganglionic fibers of the vagus nerve (Helms, 1998). The effect of acetylcholine is dependent on its receptor. ... However, receptors in skeletal muscle have the reverse effect when treated with acetylcholine; that is, they contract rather vigorously. ... magna, while acetylcholine will cause a decrease in heart rate. ... Two drops of acetylcholine was then added, at a concentration level of 1:10,000, to the D. ... After taking all five readings, the corner of a Kimwipe was once again used to wipe off the excess acetylcholine, and two drops of culture fluid were then added to the specimen. ... magna was treated with acetylcholine, and an overall increase in heart rate when treated with epinephrine. ... magna’s heart rate when treated with acetylcholine. ... magna Figure 2: The Effects of Acetylcholine on the Heart Rate of D. ... The data regarding acetylcholine supported the hypothesis that subjecting the D. ... As Campbell stated, the acetylcholine inhibits certain channels in the heart necessary for strong contractions. This allows the body to use acetylcholine within the body to bring the heart rate back to a normal level after the heart has experienced an increase in activity (Campbell, 1999). ... According to Helms, epinephrine and acetylcholine are among the most common neurotransmitters in both invertebrates and vertebrates, which make studies on the factors affecting them very important to us (Helms, 1998). After further analysis of Figures 2 and 3, one will note that both acetylcholine and epinephrine showed some unexpected trends at both the beginning and the end of the experiment.