Textbook Question
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
Tissue perfusion to the heart decreases during systole and increases during diastole.
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Ch. 17 The Cardiovascular System I: The Heart
Amerman2nd EditionHuman Anatomy & PhysiologyISBN: 9780136873822
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Table of contents
- Ch. 1 Introduction to Anatomy and Physiology26
- Ch. 2 The Chemistry of Life38
- Ch. 3 The Cell55
- Ch. 4 Histology47
- Ch. 5 The Integumentary System30
- Ch. 6 Bones and Bone Tissue36
- Ch. 7 The Skeletal System40
- Ch. 8 Articulations19
- Ch. 9 The Muscular System36
- Ch. 10 Muscle Tissue and Physiology29
- Ch. 11 Introduction to the Nervous System and Nervous Tissue28
- Ch. 12 The Central Nervous System42
- Ch. 13 The Peripheral Nervous System41
- Ch. 14 The Autonomic Nervous System and Homeostasis31
- Ch. 15 The Special Senses39
- Ch. 16 The Endocrine System42
- Ch. 17 The Cardiovascular System I: The Heart30
- Ch. 18 The Cardiovascular System II: The Blood Vessels43
- Ch. 19 Blood32
- Ch. 20 The Lymphatic System and Immunity45
- Ch. 21 The Respiratory System27
- Ch. 22 The Digestive System27
- Ch. 23 Metabolism and Nutrition7
- Ch. 24 The Urinary System39
- Ch. 25 Fluid, Electrolyte, and Acid-Base Homeostasis39
- Ch. 26 The Reproductive System10
- Ch. 27 Development and Heredity5
Chapter 17, Problem 17
An increase in preload causes a/an ________ in stroke volume in accordance with the ________ law. An increase in afterload causes a/an ________ in stroke volume. An increase in contractility causes a/an ________ in stroke volume.
Verified step by step guidance1
Understand the concept of preload: Preload refers to the degree of stretch in the cardiac muscle fibers at the end of diastole, just before contraction. According to the Frank-Starling law, an increase in preload leads to an increase in stroke volume because the stretched muscle fibers generate a stronger contraction.
Understand the concept of afterload: Afterload is the resistance the heart must overcome to eject blood during systole. An increase in afterload typically decreases stroke volume because the heart has to work harder to push blood against the higher resistance.
Understand the concept of contractility: Contractility refers to the intrinsic ability of the cardiac muscle to contract, independent of preload and afterload. An increase in contractility enhances the force of contraction, leading to an increase in stroke volume.
Apply the Frank-Starling law to preload: Recall that the Frank-Starling law explains the relationship between preload and stroke volume. Increased preload stretches the cardiac muscle fibers, resulting in a stronger contraction and increased stroke volume.
Summarize the relationships: Increased preload leads to increased stroke volume (Frank-Starling law), increased afterload leads to decreased stroke volume, and increased contractility leads to increased stroke volume.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Preload
Preload refers to the initial stretching of the cardiac muscle fibers prior to contraction, which is influenced by the volume of blood returning to the heart. An increase in preload typically leads to an increase in stroke volume, as described by the Frank-Starling law, which states that the heart pumps more effectively when it is filled with more blood.
Afterload
Afterload is the pressure against which the heart must work to eject blood during systole. An increase in afterload can lead to a decrease in stroke volume because the heart has to exert more force to overcome this resistance, which can limit the amount of blood ejected with each heartbeat.
Contractility
Contractility refers to the intrinsic ability of cardiac muscle fibers to contract and generate force. An increase in contractility enhances the heart's ability to pump blood, resulting in an increase in stroke volume. This is often influenced by factors such as sympathetic nervous system activity and certain medications.
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Related Practice
Textbook Question
Which of the following statements is false?
a. The sympathetic nervous system releases epinephrine and norepinephrine, which are positive chronotropic and inotropic agents.
b. The endocrine system regulates cardiac output through chronotropic and inotropic hormones and through hormones that regulate water balance.
c. The parasympathetic nervous system releases acetylcholine and epinephrine, which are strongly negative inotropic agents.
d. Factors such as electrolyte concentrations, body temperature, and age all affect cardiac output.
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Textbook Question
A birth defect called transposition of great vessels results in the pulmonary trunk emanating from the left ventricle and the aorta stemming from the right ventricle.
Which ventricle is thicker-walled, and why?
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Textbook Question
The first heart sound is called ________ and it is caused by the closing of the ________ valves. It occurs at the beginning of the ________ phase of the cardiac cycle. The second heart sound is called ________ and it is caused by the closing of the ________ valves. It occurs at the beginning of the ________ phase of the cardiac cycle.
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Textbook Question
Cardiac output is equal to:
a. End-diastolic volume minus end-systolic volume.
b. Heart rate multiplied by stroke volume.
c. Stroke volume divided by end-diastolic volume.
d. Heart rate multiplied by preload.