Biology
Biology
11th Edition
ISBN: 9781259188138
Author: Peter H Raven, George B Johnson Professor, Kenneth A. Mason Dr. Ph.D., Jonathan Losos Dr., Susan Singer
Publisher: McGraw-Hill Education
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Chapter 49, Problem 1U

An ECG measures

a. changes in electrical potential during the cardiac cycle.

b. Ca2+ concentration of the ventricles in diastole.

c. the force of contraction of the atria during systole.

d. the volume of blood being pumped during the contraction cycle.

Expert Solution & Answer
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Summary Introduction

Introduction:

Heart is the pumping organ of humans. Its function is to pump blood in aorta which is the biggest artery of humans. This artery then subdivides into various different arteries like the superior vena cava inferior vena cava hepatic artery and some others. The pumping of blood is done by the generation of electrical pulse which is generated by the AV node which is also called pacemaker.

Answer to Problem 1U

Correct answer:

An ECG is a procedure that is used to measure the “changes in the electric potential during a cardiac cycle”. Therefore option a. is correct.

Explanation of Solution

Reason for the correct statement:

Electrocardiogram is a device to measure the electrical conductivity of heart. Its values are obtained in the form of a graph which is called electro cardiogram. This graph has four peaks called the P, Q, R, S peaks. These peaks tell about the electrical conductivity of the heart of a person. The highest peak is R and the smallest peak is the S peak.

Option a. is given as “changes in electrical potential during the cardiac cycle”.

As, “an ECG is used to measure the electrical conductivity or potential during a cardiac cycle”, is the correct answer.

Hence, the option a. is correct.

Reasons for the incorrect statements:

Option b. is given as “Ca2+ concentration of the ventricles in a diastole”.

An ECG is used for measuring electrical potential during a cardiac cycle not the Ca2+ concentration of the ventricles in a diastole. So, it is a wrong answer.

Option c. is given as “the force of contraction of the atria during systole"”.

The purpose of an ECG is to measure the electrical conductivity of heart during a cardiac cycle not the force of contraction of the atria during systole". So it is a wrong answer.

Option d. is given as “the volume of blood being pumped during the contraction cycle"”.

The aim an ECG is to measure the electrical conductivity of heart during a cardiac cycle and not the volume of blood being pumped during the contraction cycle". So it is a wrong answer.

Hence, options b., c. and d. are incorrect.

Conclusion

The function of an ECG is to measure the electrical conductivity of the heart. The electrical impulse is generated by pacemaker of the body.

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