The heart is probably one of the most important muscles in an organism's body. It is what drives the flow of nutrients, oxygen, and other vital cells across an organism's body. In different organisms the heart can have slightly different anatomical features as compared to other organisms. In humans, the heart is divided into 4 chambers; the left and right atriums as well as the left and right ventricles. Each chamber is separated by muscle walls and by special valves, the semi lunar and cuspids, which allow blood to flow into appropriate chambers and to make sure oxygenated blood and deoxygenated blood do not mix, allowing for 100% separation.
[...] Although the heart is able to regulate itself, the nervous system is able to regulate the strength and duration of contractions. The parasympathetic sends signals through the Vagus nerve to Acetylcholine receptors on the heart which decreases cardiac output. The sympathetic nervous system uses epinephrine and Norepinephrine receptors to increase the cardiac output of the heart. Acetylcholine, released from nerves from the parasympathetic system, attaches to acetylcholine receptors of autorhythmic cells. This causes an influx of Ca2+ and efflux of which hyperpolarization of the cell and a decrease in rate of depolarization, which in turn decreases the heart rate. [...]
[...] Condition Heart Strength of Duration of Other Changes Rate(bpm) Contraction Contraction[C], Relaxation[R] and AV interval Atropine Discussion Our data showed that addition of epinephrine increases the heart rate of the frog heart and it also decreases the time of a contraction and relaxation of the heart muscles. This supports our prediction of the effect of epinephrine. The increased activity is due to the increased influx of Ca2+ and Na+ which increase the rate of depolarization. The increased amplitude of the ECG wave shows the increase in depolarization rate due to the steeper slops of the QRS complexes. [...]
[...] This can mean that the acetylcholine we added didn't cause the decrease in heart rate but possibly the frogs parasympathetic system was responsible. After Atropine was added there was an increase in cardiac activity similar to the effects of epinephrine. By this point our data might be highly unreliable because the frog has not been given time to recover from the effects of the drugs and is undergoing very stressful and unnatural experiences. A possible reason why heart activity went up might be because atropine blocked any acetylcholine from binding to their receptors and some left over epinephrine cause the increased heart activity. [...]
[...] During the flight-or-fight response the sympathetic nervous system releases epinephrine which increases the heart rate in order to pump more oxygen to the skeletal muscles that require it. In this experiment we measured the mechanical and electrical activity of the Frog heart. We also measured the effects of different drugs on the activity of the heart. The drugs that were used are Epinephrine, Acetylcholine, and Atropine. We hypothesized that these different drugs would affect the activity of the heart. We predicted that Epinephrine would increase the activity of the heart while Acetylcholine would decrease activity. [...]
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