Textbook Question
Define cardiac cycle, and follow the events of one cycle.
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Ch. 18 The Cardiovascular System: The Heart
Hoehn, Haynes, Abbott12th EditionMarieb Human Anatomy & PhysiologyISBN: 9780138242732
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Table of contents
- Ch. 1 The Human Body: An Orientation25
- Ch. 2 Chemistry Comes Alive24
- Ch. 3 Cells: The Living Units24
- Ch. 4 Tissue: The Living Fabric19
- Ch. 5 The Integumentary System12
- Ch. 6 Bones and Skeletal Tissues19
- Ch. 7 The Skeleton14
- Ch. 8 Joints7
- Ch. 9 Muscles and Muscle Tissue26
- Ch. 10 The Muscular System25
- Ch. 11 Fundamentals of the Nervous System and Nervous Tissue23
- Ch. 12 The Central Nervous System25
- Ch. 13 The Peripheral Nervous System and Reflex Activity30
- Ch. 14 The Autonomic Nervous System16
- Ch. 15 The Special Senses26
- Ch. 16 The Endocrine System26
- Ch. 17 Blood27
- Ch. 18 The Cardiovascular System: The Heart25
- Ch. 19 The Cardiovascular System: Blood Vessels27
- Ch. 20 The Lymphatic System and Lymphoid Organs and Tissues16
- Ch. 21 The Immune System: Innate and Adaptive Body Defenses27
- Ch. 22 The Respiratory System21
- Ch. 23 The Digestive System31
- Ch. 24 Nutrition, Metabolism, and Energy Balance26
- Ch. 25 The Urinary System26
- Ch. 26 Fluid, Electrolyte, and Acid-Base Balance24
- Ch. 27 The Reproductive System24
- Ch. 28 Pregnancy and Human Development25
- Ch. 29 Heredity11
Hoehn, Haynes, Abbott12th EditionMarieb Human Anatomy & PhysiologyISBN: 9780138242732Not the one you use?Change textbook
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Hoehn, Haynes, Abbott 12th EditionCh. 18 The Cardiovascular System: The HeartProblem 15
Hoehn, Haynes, Abbott 12th EditionCh. 18 The Cardiovascular System: The HeartProblem 15Chapter 18, Problem 15
The activity of the heart depends on intrinsic properties of cardiac muscle and on neural factors. Thus:
a. Vagus nerve stimulation of the heart reduces heart rate
b. Sympathetic nerve stimulation of the heart decreases time available for ventricular filling
c. Sympathetic stimulation of the heart increases its force of contraction
d. All of the above
Verified step by step guidance1
Step 1: Understand the role of the vagus nerve in heart function. The vagus nerve is part of the parasympathetic nervous system and generally acts to slow down the heart rate by releasing acetylcholine, which decreases the rate of depolarization in the sinoatrial (SA) node.
Step 2: Consider the effect of sympathetic nerve stimulation on the heart rate and ventricular filling time. Sympathetic stimulation increases heart rate, which reduces the duration of diastole, thereby decreasing the time available for ventricular filling.
Step 3: Analyze how sympathetic stimulation affects the force of contraction. Sympathetic nerves release norepinephrine, which increases calcium availability in cardiac muscle cells, enhancing the force of contraction (positive inotropic effect).
Step 4: Evaluate each statement individually based on the physiological effects described: (a) vagus nerve stimulation reduces heart rate, (b) sympathetic stimulation decreases ventricular filling time, and (c) sympathetic stimulation increases contraction force.
Step 5: Conclude whether all statements are correct by confirming that each aligns with known cardiac physiology, leading to the correct choice among the options.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Autonomic Nervous System Regulation of the Heart
The autonomic nervous system controls heart activity through two main branches: the parasympathetic (vagus nerve) and sympathetic nerves. The vagus nerve decreases heart rate by releasing acetylcholine, which slows the pacemaker cells. In contrast, sympathetic stimulation increases heart rate and contractility by releasing norepinephrine.
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Introduction to the Autonomic Nervous System Example 1
Effect of Sympathetic Stimulation on Heart Rate and Ventricular Filling
Sympathetic stimulation raises heart rate, which shortens the cardiac cycle and reduces the time available for ventricular filling during diastole. This can affect stroke volume but is compensated by increased contractile force to maintain cardiac output.
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Sympathetic Influence on Cardiac Contractility
Sympathetic nerves increase the force of heart contractions by enhancing calcium influx into cardiac muscle cells. This positive inotropic effect improves stroke volume and overall cardiac output, enabling the heart to pump more blood during stress or exercise.
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Related Practice
Textbook Question
What is cardiac output, and how is it calculated?
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Textbook Question
Describe how heart contraction and relaxation influence coronary blood flow
Name the major branches of the coronary arteries, and note the heart regions served by each
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Textbook Question
Trace one drop of blood from the time it enters the right atrium until it enters the left atrium. What is this circuit called?
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Textbook Question
Describe the pericardium and distinguish between the fibrous and the serous pericardia relative to histological structure and location.
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Textbook Question
As Cara worked at her dissection, she became frustrated that several of the structures she had to learn about had more than one common name. Provide another name for each of these structures:
a. Atrioventricular groove
b. Tricuspid valve
c. Bicuspid valve (give two synonyms)
d. Atrioventricular bundle
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