Textbook Question
Sympathetic preganglionic neurons synapse:
a. directly on target cells.
b. on skeletal muscle fibers.
c. on sympathetic chain or collateral ganglia.
d. on vagal ganglia.
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Ch. 14 The Autonomic Nervous System and Homeostasis
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 14, Problem L2.4
Common findings in heart failure are fluid retention by the kidneys and stimulation of the heart by the sympathetic nervous system. How would both of these findings help the body to compensate for the failing heart?
Verified step by step guidance1
Understand the role of fluid retention by the kidneys: The kidneys respond to reduced blood flow caused by heart failure by retaining sodium and water. This increases blood volume, which can help maintain blood pressure and improve perfusion to vital organs.
Analyze the role of the sympathetic nervous system: In heart failure, the sympathetic nervous system is activated to compensate for reduced cardiac output. It increases heart rate (tachycardia) and contractility, which can temporarily improve the pumping ability of the heart.
Connect fluid retention to preload: Increased blood volume from fluid retention raises the preload (the amount of blood returning to the heart). According to the Frank-Starling mechanism, a higher preload can enhance the heart's ability to contract and pump blood more effectively.
Relate sympathetic stimulation to afterload and systemic circulation: Sympathetic activation causes vasoconstriction, which helps maintain blood pressure in the face of reduced cardiac output. This ensures that vital organs like the brain and kidneys continue to receive adequate blood flow.
Evaluate the limitations of these compensatory mechanisms: While fluid retention and sympathetic stimulation can temporarily support circulation, they may also worsen heart failure over time by increasing the workload on the heart and contributing to congestion in tissues and lungs.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Fluid Retention
Fluid retention in heart failure occurs when the kidneys retain more sodium and water due to decreased blood flow and pressure. This compensatory mechanism aims to increase blood volume, which can help maintain cardiac output despite the heart's reduced ability to pump effectively. However, excessive fluid retention can lead to edema and increased workload on the heart.
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Serous Cavity and Fluid
Sympathetic Nervous System Activation
The sympathetic nervous system (SNS) is activated in heart failure to increase heart rate and contractility, thereby enhancing cardiac output. This response is part of the body's fight-or-flight mechanism, which helps to compensate for the heart's diminished function. While this can temporarily improve circulation, prolonged SNS activation can lead to further heart damage and worsening heart failure.
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Compensatory Mechanisms
Compensatory mechanisms in heart failure are physiological responses that aim to maintain adequate blood flow and oxygen delivery despite the heart's impaired function. These include fluid retention and SNS activation, which work together to stabilize blood pressure and improve perfusion to vital organs. However, these mechanisms can become maladaptive over time, contributing to the progression of heart failure.
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Related Practice
Textbook Question
Describe all the changes initiated by the parasympathetic nervous system that will take place when you finish the race. How will these changes maintain homeostasis?
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Textbook Question
Mr. Chevalier has been diagnosed with Horner syndrome, which is caused by dysfunction of the sympathetic neurons in the superior cervical ganglion that innervate structures of the head, face, and neck. What symptoms is Mr. Chevalier likely to face due to his disease? Explain.
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Textbook Question
The drug neostigmine blocks the activity of the enzyme acetylcholinesterase in the synaptic cleft. Predict the effects of this drug.
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Textbook Question
Using 20 or fewer words, define each of the following terms in your own words.
b. Parasympathetic nervous system
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Textbook Question
Using 20 or fewer words, define each of the following terms in your own words.
a. Sympathetic nervous system
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