Frog Lab Report

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1. Yes. The heart of the frog contracts and relaxes rhythmically. This behaviour is shown by the observation of the general fluctuations in the force values as well as the consistent patterns of the ECG which occurs in regular intervals.
2. This delay is primarily caused by the atrioventricular node (A-V node) and the adjacent conductive fibres. Conduction in cardiac muscle is hindered by the decreasing number of gap junctions along the pathway of conduction which creates a resistance against the conduction of excitatory ions, i.e. Ca2+, from one fibre to another. This ensures that the atria completely empty the blood into the ventricles before ventricular contraction occurs.
3. A typical electrocardiogram (ECG) usually shows P, Q, R,
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At a temperature of 22°C (room temperature) the beats per minute were 96.5. At a temperature of 0°C, the beats per minute decreased to 42.7. Lastly, when the temperature was increased to 40°C, the beats per minute increased to 134.5. The heart rate in this experiment has a direct relationship to the temperature of the Ringer’s solution. Poikilotherms are defined as animals or organisms that are directly influenced by the temperature of their environment. This results in the frog’s body temperature being more affected by the temperature of the environment and the heart having to constantly increase or decrease its …show more content…
Stroke volume is predicted to increase during physical exercise. This refers to to the amount of blood pumped out of the ventricles per heartbeat. Exercise causes a relatively small increase in body temperature, which increases the contractile strength of the heart. As a result, this elevates the stroke volume in a way that is independent of the final diastolic volume.
9. Acetylcholine is a hormone released by the parasympathetic nervous system (PNS). It affects the heart by lowering the rhythm of the sinus node and the excitation capacity of the AV junction fibres between the muscles in the atria and the AV node, decreasing the speed of transmission of the cardiac impulse into the ventricles.
10. Epinephrine (adrenaline) is a hormone released by the adrenal medulla that increases blood pressure and heart rate. Feelings such as fear or excitement stimulate the release of this hormone into the blood. When epinephrine binds to receptors of a heart muscle, it stimulates a signal transduction process that results in an increased heart rate and more forceful muscle

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