Essay On Pacemaker Contraction

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Pacemaker cell activity is very important for heart rate and force of contraction of the heart. There is no constant resting potential (Figure.2), it's due to a leak of Na+ ions. That leaks causes Na+ ions moves into the cell and depolarises the cells until a threshold that activate voltage gated Ca+ channels and voltage gated K+ channels. Anova 1, with values of each section of time after injection of Ringer's solution, shows a p-value of 0.9513. Thus, we are sure at more than 95% that values aren't significantly differents between the three groups. So Ringer's solution have no effect on heart rate or amplitude. Ringer it's our normal conditions control, it doesn't affect heart rate or amplitude (=force of heart contraction). Anova 1, with values at 60s after injection of each products, shows a p-value inferior to 0.0001. Thus, we are sure at more than 99.9999% that values are significantly differents between the three groups. Tukey tests show that a p-value inferior to 0.01 between M1-M2 and M1-M3 and a p-value inferior to 0.05 between M2-M3. So,…show more content…
Frog or other amphibians have a myogenic heart with only 3 cavities (2 atria and 1 ventricle) because of that there is a mix of oxygenated and deoxygenated blood in the ventricle prevent by ventricular folding. In mamals the heart have four cavities so it is bigger than the precedent one. The fourth cavity separates completely oxygenated blood from de-oxygenated blood. It allows the blood leaving the heart to have more oxygen than in amphibians myogenic heart because there is no mixing of blood. Tissues, organs, cells will have more oxygen so more energy. That can play a role in the behaviour of the organisms. Myogenic heart used specialized groups of muscle cells to initiate and regulate heart activity. In contract, insects have a neurogenic heart. They use external nerves to initiate and regulate heart
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