Question

(i) During a cardiac cycle each ventricle pumps out approximately $70$mL of blood which is called the stroke volume.
(ii) The cardiac output of an athlete will be much higher than that of an ordinary man.
(iii) The body has no the ability to alter the stroke volume and the cardiac output.
(iv) The cardiac output can be defined as the volume of blood pumped out by each ventricle per minute.
(v) Volume of blood pumped by left ventricle is higher than blood pumped by right ventricle.
How many statements are correct?

• A. Two
• B. Three
• C. Four
• D. Five

Answer 1

Answer: (D)

Five

The correct answer is D.

1) Stroke volume is the difference between end-diastolic and end-systolic volumes; it is the volume ejected with each heart beat. The normal range is 50 to 100 ml.

2) Cardiac output may increase to 35L/min in well-trained athletes. In untrained individuals it can reach 20-25L/min. Most of the increase in cardiac output goes to the exercising muscles. There is an increase in blood flow to skin (dissipation of heat) and to the heart (increased work performed by the heart).

3) Given this stroke volume and a normal heart rate of 70 beats per minute, cardiac output is 5.25 L/min. When heart rate or stroke volume increases, cardiac output is likely to increase also. Conversely, a decrease in heart rate or stroke volume can decrease cardiac output.

4) Cardiac output is the volume of blood being pumped by the heart in a minute. It is equal to the heart rate multiplied by the stroke volume.

5) The left ventricle of the heart is larger and thicker than the right ventricle. This is because it has to pump the blood further around the body, and against higher pressure, compared with the right ventricle