Final answer:
Approximately 20% of the blood pumped by the heart goes to the kidneys for filtration and plays a key role in regulating various bodily functions.
Step-by-step explanation:
Approximately 20% of cardiac blood goes to the kidneys. The heart pumps about 5 liters of blood per minute while at rest, and around 20% of this blood, which equals to one liter, is delivered to the kidneys for filtration. The kidneys, receiving about 1,000 to 1,200 milliliters of blood per minute, play a crucial role in filtering wastes, reabsorbing useful substances, and secreting excesses. This process is also involved in regulating blood volume and pressure, as well as being essential for the renin-angiotensin-aldosterone system, which regulates fluid balance and blood pressure.