What is the approximate total blood volume of an average-sized adult?

• A. About 10 liters (approximately 9–11 L)
• B. About 5 liters (approximately 4–6 L)
• C. About 20 liters (approximately 18–22 L)
• D. About 0.5 liters (approximately 0.4–0.6 L)

Answer: (B)

Verified step by step guidance

1. Understand that total blood volume refers to the amount of blood circulating within the entire vascular system of an average adult human.
2. Recall that the average adult blood volume is typically estimated based on body weight, with a common approximation being about 7-8% of total body weight.
3. Recognize that for an average adult weighing around 70 kg, this percentage translates to roughly 5 liters of blood.
4. Note that the range can vary slightly depending on factors such as sex, body composition, and hydration status, generally falling between 4 to 6 liters.
5. Conclude that among the given options, the value closest to this physiological range is 'About 5 liters (approximately 4–6 L)'.