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Ch. 18 The Cardiovascular System: The Heart
Marieb - Human Anatomy & Physiology 11th Edition
Marieb, Hoehn11th EditionHuman Anatomy & PhysiologyISBN: 9780136874034Not the one you use?Change textbook
All textbooksMarieb, Hoehn 11th EditionCh. 18 The Cardiovascular System: The HeartProblem 4
Chapter 18, Problem 4

The sequence of contraction of the heart chambers is:
a. Random
b. Left chambers followed by right chambers
c. Both atria followed by both ventricles
d. Right atrium, right ventricle, left atrium, left ventricle

Verified step by step guidance
1
Understand the basic physiology of the heart's conduction system, which controls the sequence of contraction in the heart chambers.
Recall that the sinoatrial (SA) node initiates the electrical impulse, causing both atria to contract almost simultaneously.
Recognize that after atrial contraction, the impulse travels to the atrioventricular (AV) node, then through the bundle of His and Purkinje fibers, leading to ventricular contraction.
Note that both ventricles contract nearly at the same time following atrial contraction to efficiently pump blood to the lungs and the rest of the body.
Conclude that the correct sequence is both atria contracting first, followed by both ventricles contracting together.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Cardiac Cycle

The cardiac cycle refers to the sequence of events in one heartbeat, including contraction (systole) and relaxation (diastole) of the heart chambers. Understanding this cycle is essential to know how blood flows through the heart and the timing of chamber contractions.
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Events in the Cardiac Cycle

Atrial and Ventricular Contraction Sequence

The heart contracts in a coordinated manner where both atria contract first to push blood into the ventricles, followed by the contraction of both ventricles to pump blood out to the lungs and body. This sequence ensures efficient blood flow and prevents backflow.
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Overview of Muscle Contraction

Electrical Conduction System of the Heart

The heart's contraction sequence is controlled by its electrical conduction system, starting at the sinoatrial (SA) node, causing atrial contraction, then passing to the atrioventricular (AV) node and Purkinje fibers to trigger ventricular contraction. This system ensures the proper timing of chamber contractions.
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Electrical Conduction System of the Heart Example 2
Related Practice
Textbook Question

The fact that the left ventricular wall is thicker than the right reveals that it:

a. Pumps a greater volume of blood

b. Pumps blood against greater resistance

c. Expands the thoracic cage

d. Pumps blood through a smaller valve

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Textbook Question

When the semilunar valves are open, which of the following are occurring?

(1) Coronary arteries fill

(2) AV valves are closed

(3) Ventricles are in systole

(4) Ventricles are in diastole

(5) Blood enters the aorta

(6) Blood enters pulmonary arteries

(7) Atria contract

a. 2, 3, 5, 6

b. 1, 2, 3, 7

c. 1, 3, 5, 6

d. 2, 4, 5, 7

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Textbook Question

In the heart, which of the following apply?

(1) Action potentials are conducted from cell to cell across the myocardium via gap junctions

(2) The SA node sets the pace for the heart as a whole

(3) Spontaneous depolarization of cardiac cells can occur in the absence of nerve stimulation

(4) Cardiac muscle can continue to contract for long periods in the absence of oxygen

a. All of the above

b. 1, 3, 4

c. 1, 2, 3

d. 2, 3

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Textbook Question

An ECG provides information about:

a. Cardiac output

b. Movement of the excitation wave across the heart

c. Coronary circulation

d. Valve impairment

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Textbook Question

The chordae tendineae:

a. The atrioventricular valves

b. Prevent the AV valve flaps from everting

c. Contract the papillary muscles

d. Open the semilunar valves

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