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Ch. 14 The Autonomic Nervous System and Homeostasis
Amerman- Human Anatomy & Physiology 3e
Amerman3rd EditionHuman Anatomy & PhysiologyISBN: 9780138247201, 9780138247928, 9780138201814Not the one you use?Change textbook
All textbooksAmerman 3rd EditionCh. 14 The Autonomic Nervous System and HomeostasisProblem 7
Chapter 14, Problem 7

Which of the following actions would you expect when sympathetic neurons release norepinephrine onto β1 receptors?
a. Decreased sweat production
b. Constriction of blood vessels serving the digestive, urinary, and integumentary systems
c. Adjustment of the shape of the lens
d. Increase in the rate and force of contraction of the heart.

Verified step by step guidance
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Step 1: Understand the role of sympathetic neurons in the autonomic nervous system. Sympathetic neurons are part of the 'fight or flight' response, which prepares the body for action by increasing heart rate, dilating airways, and redirecting blood flow to essential organs like muscles.
Step 2: Learn about norepinephrine and its interaction with β1 receptors. Norepinephrine is a neurotransmitter released by sympathetic neurons, and β1 receptors are primarily found in the heart. Activation of β1 receptors leads to increased heart rate and stronger heart contractions.
Step 3: Analyze the options provided in the question. For each option, determine whether it aligns with the effects of norepinephrine binding to β1 receptors. For example, decreased sweat production (option a) is not related to β1 receptor activation, as sweat production is controlled by different receptors.
Step 4: Focus on the physiological effects of β1 receptor activation. Activation of β1 receptors specifically increases the rate and force of heart contractions, which is consistent with the body's need to pump more blood during a 'fight or flight' response.
Step 5: Eliminate incorrect options based on your understanding of β1 receptor activation and sympathetic nervous system functions. For example, constriction of blood vessels serving the digestive, urinary, and integumentary systems (option b) is mediated by α1 receptors, not β1 receptors. Adjustment of the shape of the lens (option c) is controlled by parasympathetic neurons, not sympathetic neurons.

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Key Concepts

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

Sympathetic Nervous System

The sympathetic nervous system is a part of the autonomic nervous system that prepares the body for 'fight or flight' responses during stressful situations. It increases heart rate, dilates airways, and redirects blood flow to essential organs, enhancing physical performance. Understanding its role is crucial for interpreting how norepinephrine affects various body functions.
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Sympathetic Nervous System Example 3

Norepinephrine and β1 Receptors

Norepinephrine is a neurotransmitter that binds to adrenergic receptors, including β1 receptors, primarily found in the heart. Activation of β1 receptors leads to increased heart rate and contractility, which enhances cardiac output. This concept is essential for understanding the physiological effects of sympathetic stimulation on the heart.
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Sensory Receptors

Physiological Responses to Sympathetic Activation

When sympathetic neurons are activated, various physiological responses occur, such as increased heart rate, blood vessel constriction, and altered glandular secretions. These responses are part of the body's mechanism to cope with stress. Recognizing these responses helps in predicting the outcomes of norepinephrine release on different organs and systems.
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Related Practice
Textbook Question

Which neurotransmitter(s) is/are used by sympathetic postganglionic neurons?


a. Epinephrine

b. Norepinephrine

c. Acetylcholine

d. Both a and b

e. All of the above

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Textbook Question

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

b. Sympathetic stimulation increases sweat secretion.

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Textbook Question

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

a. The parasympathetic nervous system generally decreases the secretion from digestive glands.

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Textbook Question

Differentiate between adrenergic and cholinergic receptors.

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Textbook Question

Mark each of the following as an effect of the sympathetic nervous system or the parasympathetic nervous system.

a. ________ Bronchodilation

b.________ Bronchoconstriction

c. ________ Constriction of pupil

d. ________ Vasoconstriction of blood vessels serving organs of digestive, urinary, and integumentary systems

e. ________ Increased metabolic rate

f. ________ Dilation of pupil

g.________ Contraction of smooth muscle of digestive tract

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Textbook Question

Explain what happens when sympathetic neurons stimulate the adrenal medulla. What purpose does this serve?

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