Q10 - Why the Heart Can't Suck Blood: The Frank-Starling Mechanism

Theoretical B Real exam question - full text reproduced under IBO's CC BY-NC-SA 4.0 license

William Harvey (1578-1657) discovered that the heart pumps blood around the body in a circuit. Ernest Starling (1866-1927) discovered many of the fundamental properties of the circulatory system, including how cardiac output (the amount of blood pumped in a given time) is controlled. Starling completely removed a beating heart from the body, and attached it to an apparatus that allowed him to alter the pressure of incoming ‘venous’ (1) or outgoing ‘arterial’ blood (2). He then measured cardiac output. Both the left and right-sides of the heart gave similar results.

Figure 1 for Q10: Why the Heart Can’t Suck Blood: The Frank-Starling Mechanism

Using the information and data, determine which of the statements are true or which are false.

A. Responses to exercise include toning (contraction of smooth muscle) of the veins.

B. If outflow from the right-side of the heart increases, nervous or hormonal coordination is required for outflow from the left-side of the heart to match it.

C. The energy required for the heart to beat increases as venous blood pressure increases.

D. In the early stages of heart failure, cardiac output can be maintained if blood volume is increased.

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Question reproduced from IBO 2017, Theoretical Exam B, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Official answer key & worked solutions