心血管系統：练习题

Which energy system provides the majority of adenosine triphosphate (ATP) during a single maximal effort lasting less than 6 seconds, such as a standing long jump?

In the cardiac conduction system, what is the correct order of the pathway taken by an electrical impulse to cause ventricular contraction?

Which of the following best describes the physiological state of Excess Post-exercise Oxygen Consumption (EPOC) and its relationship to the 'slow' component of recovery?

According to Starling’s law of the heart, what is the primary factor that causes an increase in stroke volume during exercise?

During exercise, oxygen must diffuse from the blood into the working muscle cells. Which of the following conditions at the muscle site facilitates this diffusion?

Identify the venous return mechanism consisting of one-way structures within the veins that prevent the backflow of blood as it travels from the lower extremities towards the heart.

A sports scientist measures an endurance runner's Respiratory Exchange Ratio (RER) during a steady-state run. The recorded value is exactly \(0.70\).

Identify the primary fuel source being utilized and explain what this value indicates regarding the relative volumes of \(VCO_{2}\) produced and \(VO_{2}\) consumed.

Identify the specific joint action and the main agonist muscle occurring at the ankle during the upward phase of a calf raise.

(a) Define the term stroke volume.

(b) A sedentary individual has a resting heart rate of \(72\) beats per minute and a stroke volume of \(70\,ml\). Calculate their resting cardiac output (\(Q\)) in litres per minute (\(L/min\)).

A marathon runner is competing on a hot, humid day. During the latter stages of the race, their stroke volume begins to decrease despite maintaining a constant exercise intensity.

(a) Identify this physiological phenomenon and explain why stroke volume decreases in these conditions.

(b) In order to maintain a constant cardiac output (\(Q\)), explain the necessary change in heart rate and identify the relationship used to calculate cardiac output.