Anatomy & Physiology: The Unity of Form and Function, 7th Edition

Published by McGraw-Hill Education
ISBN 10: 0073403717
ISBN 13: 978-0-07340-371-7

Chapter 15 - The Autonomic Nervous System and Visceral Reflexes - Study Guide - Testing Your Comprehension - Page 577: 3

Answer

If the cardiac nerves were destroyed, it would have a significant impact on the heart's ability to respond to stress and could affect the overall functioning of the cardiovascular system. The cardiac nerves, which include the sympathetic and parasympathetic nervous systems, play a vital role in regulating heart rate and cardiac function. Here's how the destruction of cardiac nerves would affect the heart and the body's ability to react to a stressful situation: 1. **Loss of Autonomic Control:** The cardiac nerves, particularly the sympathetic and parasympathetic branches, provide the autonomic (involuntary) control of the heart. The sympathetic nervous system typically increases heart rate and contractility during stress, while the parasympathetic system slows it down during rest. Without these nerves, the heart would lose its ability to respond dynamically to changes in stress levels. 2. **Inability to Adjust Heart Rate:** Under normal circumstances, the sympathetic nervous system increases heart rate in response to stressors, helping prepare the body for "fight or flight." If the cardiac nerves were destroyed, the heart would not receive these signals, making it less capable of adjusting heart rate to meet the demands of a stressful situation. 3. **Risk of Inadequate Oxygen Supply:** During stressful situations, the body's demand for oxygen and nutrients increases. The heart, through sympathetic stimulation, normally responds by increasing cardiac output. Without this adjustment, the heart might not pump enough blood to meet the increased oxygen demands of the body's tissues, potentially leading to oxygen deprivation in vital organs. 4. **Decreased Adaptability:** The ability to rapidly adapt to changing conditions, such as sudden physical exertion or stress, would be compromised. The heart would not be able to respond as efficiently to sudden demands for increased blood flow and oxygen delivery. 5. **Altered Stress Response:** The body's overall stress response, including the "fight or flight" response, relies on the autonomic nervous system's coordination. Without proper heart rate adjustments and other cardiovascular responses, the body's ability to react effectively to stressful situations would be impaired. 6. **Risk of Arrhythmias:** The absence of autonomic control over the heart can increase the risk of arrhythmias (abnormal heart rhythms) and other cardiac issues. The heart may become less stable in its function. 7. **Impact on Blood Pressure:** The sympathetic nervous system also plays a role in regulating blood pressure. Without its input, blood pressure regulation could be compromised, which might lead to problems like orthostatic hypotension (a drop in blood pressure upon standing) or hypertension (persistently high blood pressure). In summary, the destruction of cardiac nerves, particularly the sympathetic and parasympathetic components, would disrupt the heart's ability to respond to stress appropriately and could compromise the body's ability to react effectively in stressful situations. This could result in inadequate oxygen delivery to tissues, altered stress responses, and potential cardiovascular issues.

Work Step by Step

If the cardiac nerves were destroyed, it would have a significant impact on the heart's ability to respond to stress and could affect the overall functioning of the cardiovascular system. The cardiac nerves, which include the sympathetic and parasympathetic nervous systems, play a vital role in regulating heart rate and cardiac function. Here's how the destruction of cardiac nerves would affect the heart and the body's ability to react to a stressful situation: 1. **Loss of Autonomic Control:** The cardiac nerves, particularly the sympathetic and parasympathetic branches, provide the autonomic (involuntary) control of the heart. The sympathetic nervous system typically increases heart rate and contractility during stress, while the parasympathetic system slows it down during rest. Without these nerves, the heart would lose its ability to respond dynamically to changes in stress levels. 2. **Inability to Adjust Heart Rate:** Under normal circumstances, the sympathetic nervous system increases heart rate in response to stressors, helping prepare the body for "fight or flight." If the cardiac nerves were destroyed, the heart would not receive these signals, making it less capable of adjusting heart rate to meet the demands of a stressful situation. 3. **Risk of Inadequate Oxygen Supply:** During stressful situations, the body's demand for oxygen and nutrients increases. The heart, through sympathetic stimulation, normally responds by increasing cardiac output. Without this adjustment, the heart might not pump enough blood to meet the increased oxygen demands of the body's tissues, potentially leading to oxygen deprivation in vital organs. 4. **Decreased Adaptability:** The ability to rapidly adapt to changing conditions, such as sudden physical exertion or stress, would be compromised. The heart would not be able to respond as efficiently to sudden demands for increased blood flow and oxygen delivery. 5. **Altered Stress Response:** The body's overall stress response, including the "fight or flight" response, relies on the autonomic nervous system's coordination. Without proper heart rate adjustments and other cardiovascular responses, the body's ability to react effectively to stressful situations would be impaired. 6. **Risk of Arrhythmias:** The absence of autonomic control over the heart can increase the risk of arrhythmias (abnormal heart rhythms) and other cardiac issues. The heart may become less stable in its function. 7. **Impact on Blood Pressure:** The sympathetic nervous system also plays a role in regulating blood pressure. Without its input, blood pressure regulation could be compromised, which might lead to problems like orthostatic hypotension (a drop in blood pressure upon standing) or hypertension (persistently high blood pressure). In summary, the destruction of cardiac nerves, particularly the sympathetic and parasympathetic components, would disrupt the heart's ability to respond to stress appropriately and could compromise the body's ability to react effectively in stressful situations. This could result in inadequate oxygen delivery to tissues, altered stress responses, and potential cardiovascular issues.
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