Laboratory Manual For Human Anatomy & Physiology
4th Edition
ISBN: 9781260159363
Author: Martin, Terry R., Prentice-craver, Cynthia
Publisher: McGraw-Hill Publishing Co.
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Textbook Question
Chapter 45, Problem 1PL
The _______ of the conduction system is known as the pacemaker.
a. SA node
b. AV node
c. AV bundle
d. left bundle branch
Expert Solution & Answer
Summary Introduction
Introduction:
In animals, the heart is a muscular organ which pumps blood via circulatory system throughout the body. Blood gives oxygen and nutrients to the body, and removes metabolic wastes. The heart is placed just behind and moderately left of the sternum (breastbone) in humans.
In humans, birds and some other mammals, the heart is partitioned into four chambers: the upper right and left atria and the lower right and left ventricle.
A pacemaker is a medical machine that is situated at the top of the heart's right atrium to help control abnormal (or unusual) heart rates. This machine utilizes electrical pulses to imply the heart to beat (or vibrate) at a normal rate. The pacemaker is used to treat arrhythmias. Arrhythmias are the problem with the rhythm or rate of the heartbeat.
Answer to Problem 1PL
Correct answer:
The correct answer is option (a) SA node.
Explanation of Solution
Explanation/justification for the correct answer:
Option (a) SA node. The natural pacemaker of the heart is SA node. These cells can produce electrical impulses spontaneously. The chief function of a sinoatrial (SA) node cell is to begin the action potential of the heart so that it can pass through the whole heart and provoke contraction. So, this is the correct option.
Explanation for incorrect answer:
Option (b) AV node. The tricuspid valve and the mitral valve are identified as the atrioventricular (AV) valve and attach the atrium to the ventricle. Both valves are positioned between the upper chambers (atria) and lower chambers (ventricles) and prevent the backflow of the blood from the ventricles into the atria during systole. So, this is an incorrect option.
Option (c) AV bundle. A bundle of specialized muscle fibers controls the heartbeat by conducting impulses from the right atrium of the ventricle is known as the AV bundle. AV bundle also termed as bundle of His. It transmits impulses from the ventricular note to the ventricles of the heart. So, this is an incorrect option.
Option (d) left bundle branch. The left bundle branch carries electrical signals to the bottom of the heart and causes the ventricles to beat. So, this is an incorrect option.
Conclusion
The SA node of the conduction system is known as the pacemaker. Hence, the correct answer is option (a) SA node.
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Chapter 45 Solutions
Laboratory Manual For Human Anatomy & Physiology
Ch. 45 - The _______ of the conduction system is known as...Ch. 45 - The ________ of the conduction system is/are...Ch. 45 - The first of two heart sounds (lubb) occurs when...Ch. 45 - One cardiac cycle would consist of a. left chamber...Ch. 45 - The SA node of the heart is located in the a....Ch. 45 - The depolarization of ventricular fibers is...Ch. 45 - The dupp sound occurs when the semilunar valves...Ch. 45 - The P wave of an ECG occurs during the...Ch. 45 - The period during a heart is contracting is called...Ch. 45 - The period during which a heart chamber is...
Ch. 45 - During ventricular contraction, the AV valves...Ch. 45 - During ventricular relaxation, the AV valves are...Ch. 45 - The pulmonary and aortic valves open when the...Ch. 45 - The first sound of a cardiac cycle occurs when the...Ch. 45 - The second sound of a cardiac cycle occurs when...Ch. 45 - The sound created when blood leaks back through an...Ch. 45 - What changes did you note in the heart sounds when...Ch. 45 - What changes did you note in the heart sounds...Ch. 45 - Prob. 3.1ACh. 45 - The ____________________ node is located in the...Ch. 45 - The fibers that carry cardiac impulses from the...Ch. 45 - Prob. 3.4ACh. 45 - The P wave corresponds to depolarization of the...Ch. 45 - The QRS complex corresponds to depolarization of...Ch. 45 - The T wave corresponds to repolarization of the...Ch. 45 - Why is atrial repolarization not observed in the...Ch. 45 - Identify the heart chambers and conduction system...Ch. 45 - How much time passed from the beginning of the P...Ch. 45 - What is the significance of this P-R interval?Ch. 45 - How can you determine heart rate from an...Ch. 45 - As blood in the ventricles surges back against the...
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