The heart is an integral part of the cardiovascular system in the body of vertebrates. It provides the pressure needed for the blood to be pumped to different parts of the body. The heart maintains the flow of blood throughout the whole cardiovascular system. This in turn allows all the separate parts of the body to be energized with oxygenated blood, maintaining a stable internal environment.
The heart plays essentially the same role in all the animals which posses it, however its structural anatomy varies somewhat from species to species. Amphibian hearts have three chambers which include the left atrium, right atrium and a single ventricle.
[...] In this lab experiment, we dissected a live frog and inspected the contractions of its heart natural and drug-induced conditions. We hypothesized that the frog's heart rate would increase with the addition of Epinephrine and that it would decrease with the addition of Acetylcholine. We predicted that the heart rate would once again increase with the addition of Atropine. We also hypothesized that epinephrine would increase the intensity (amplitude of the heart beats). Materials and Methods My group and I followed the procedure as written in Foundations of Biology: Cell and Organ Physiology (Faculty of the Department of Neurobiology and Behavior, SUSB, pg. [...]
[...] On the contrary, the parasympathetic branch is what calms the body down after extreme situations, returning the heart rate to a normal level, this branch is deemed the “rest and digest” system (Campbell 1028-1029). When the sympathetic branch of the autonomic nervous system is stimulated Norepinephrine is released, increasing both the heart rate and the strength of the cardiac muscle contraction (Campbell, 877). Epinephrine is commonly known as adrenaline, and the postganglionic nerves release it upon stimulation as well, thereby increasing the heart rate. [...]
[...] We proceeded onto Figure 3 which shows the mechanical and electrical events going on within the frog's heart after we added the drug Epinephrine. The heart rate increased to 48 beats per minute. Epinephrine is commonly known as adrenaline, so it is understandable that as it is released by the postganglionic nerves upon stimulation of the sympathetic branch of the autonomic nervous system, the heart rate increases. As epinephrine is released, the amount of calcium and sodium conductance increases. Therefore, as we added epinephrine, depolarization occurred within the frog's heart. [...]
[...] Table 1 Condition Heart Rate (BPM) Other Changes relative to control relative to control relative to acetylcholine Discussion This experiment was performed to verify the effects of certain drugs on a beating amphibian heart. Although much can be taken away from our experiment, there were too many sources of error to accurately verify the hypothesis. We were able to loosely relate the different aspects of the experiment and confirm the effects of the drugs on the amphibian's heart rate, but the intensity (amplitude) of the beats was not able to be tested accurately. [...]
[...] During the S to T interval, there was ventricular contraction and repolarization according to the mechanical reading of the heart beat above the ECG. In retrospect our hypothesis did hold up to an extent. Looking past the multitude of possible errors that could have occurred, Epinephrine did increase the heart rate, while Acetylcholine decreased it. Atropine stabilized it back to the original heart rate, albeit lowering the overall heart beat. The differences in heart beat intensity were hard to measure and therefore cannot be confirmed or refuted. [...]
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