Given that an average human has a heart rate of 70 beats per minute and if one is to have a 70 year life span, the number of times it will beat is 2,575,440,000 times. This was computed by multiply 70 years by 365 days/year x 24 hours/day x 60 minutes/hour x 70 beats/min. Thus, the heart will beat numerous times before it finally stops.
I think it’s d.
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The right atrium receives blood returning from others parts of the body through the superior vena cava and the inferior vena cava.
Explanation:
The pathway of circulation begins in the right atrium which receives the carbon dioxide-rich deoxygenated blood returning through the systemic circulation.
The deoxygenated blood from regions superior to the heart, i.e., the head, neck, shoulder areas are collected through the superior vena cava and that from the parts inferior or lower to the heart like visceral organs, extremities, trunk, hip etc are brought through the inferior vena cava.
Both these venous systems (superior and inferior) fill the right atrium.
The right atrium then pumps the deoxygenated blood to the right ventricle via the tricuspid valve.
The right atrium is filled with blood during diastole.
Carbon dioxide (CO²) is taken in to start the Calvin Cycle.
