Final answer:
Oxygen-rich blood enters the heart's left atrium from the pulmonary veins, moves to the left ventricle, and is pumped into the ascending aorta. From there, the blood travels through the coronary arteries to the myocardial capillaries, supplying the heart muscle before returning to the right atrium via the coronary veins and coronary sinus.
Step-by-step explanation:
The pathway of blood flow for one red blood cell starting with the point where oxygenated blood is received by the heart to the myocardium and up until just prior to deoxygenated blood leaving the heart includes several steps. First, oxygen-rich blood enters the left atrium through the four pulmonary veins. It is then pumped into the left ventricle and from there into the ascending aorta via the aortic valve during systole.
From the ascending aorta, the blood moves into the right and left coronary arteries, which branch off to supply the heart muscle (myocardium) with oxygen-rich blood. The blood travels through smaller arteries and reaches the myocardial capillaries, providing oxygen to the heart muscle cells.
After the blood has delivered oxygen to the myocardium, it becomes deoxygenated and is collected by coronary veins, which drain into the coronary sinus, and then the blood flows into the right atrium of the heart, completing its circuit of the myocardium.