Problem: Myocardial blood supply and heart rate. The myocardium has its own independent blood supply. The coronary arteries branch off the aorta and resemble two hands wrapping around the heart. They are made up of three main arteries: The right coronary artery The left anterior descending artery The circumflex artery. Any blockage to these arteries means a decreased blood supply and oxygen to the myocardium, which can lead to problems. A heart rate of 60 to 100 beats per minute (bpm) is in the normal range for an adult. A healthy heart should be able to tolerate a range of heart rates from 40 to 170 beats per minute (bpm) for a relatively prolonged period. However, if cardiac function is compromised, this range may be considerably narrower. Elevated heart rates can compromise cardiac output by: Increasing the amount of oxygen consumed by the myocardium Reducing the diastolic time (time between heartbeats), which means less time for perfusion of the coronary arteries Shortening the ventricular filling phase of the cardiac cycle (cardiac output is decreased). Normal electrical impulses start at the sinoatrial node and extend down to the atrioventricular (AV node, where there is a slight delay. From here, the electrical impulses head down into the Purkinje fibres and initiate the ventricles to pump. i need to summarize this paragraph so its easier for me to understand can you please do this. Need Assignment Help?