Questions and Answers
The autonomic nervous system is subject to voluntary control.
False
Preganglionic fibers release neurotransmitter onto effector organs in the autonomic nervous system pathway.
False
Acetylcholine can bind to nicotinic receptors in the autonomic nervous system.
True
Adrenergic fibers release acetylcholine.
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Most visceral (internal) organs are innervated by both sympathetic and parasympathetic nerve fibers.
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Motor neurons innervate skeletal muscle and trigger voluntary movement.
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The somatic nervous system originates in the lateral horn of the thoracic spinal cord.
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The somatic nervous system can both stimulate and inhibit effector organs.
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Afferent neurons terminate at interneurons.
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Efferent neurons carry instructions from the CNS to the effector organs.
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A neuromuscular junction is a link between two motor neurons.
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The neurotransmitter released at the neuromuscular junction is acetylcholine (ACh).
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Acetylcholinesterase (AChE) is an enzyme that keeps the muscle cell's electrical response turned on.
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Botulinum toxin acts by triggering explosive release of ACh from storage vesicles at all cholinergic sites.
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Organophosphates (example: sarin gas) irreversibly block acetylcholinesterase (AChE), resulting in respiratory failure.
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__________nerve fibers originate in the thoracic and lumbar regions of the spinal cord.
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____________ postganglionic fibers are short, terminating on the effector organs.
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Most visceral organs are innervated by _______________ nerve fibers.
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__________ dominance is concerned with general 'housekeeping' activities.
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__________ dominance promotes the 'fight or flight' response.
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Smooth muscle cells are innervated by ___________.
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_______________ receptors respond to acetylcholine released from both sympathetic and parasympathetic preganglionic fibers.
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A(n) ________ binds with the receptor and prevents the neurotransmitter from causing a response.
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The sympathetic nervous system is part of the __________ nervous system.
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The __________ nervous system promotes responses that prepare the body for strenuous physical activity.
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The ____________ nervous system dominates in quiet, relaxed situations.
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________ system promotes 'rest and digest' bodily functions.
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_____________ receptors are found on the cell membrane of cardiac muscle, smooth muscle and glands.
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The __________ division of the autonomic nervous system stimulates contraction of the bladder wall.
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Stimulation of the _________ division of the autonomic nervous system causes an increased heart rate.
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The parasympathetic and sympathetic nerve fibers innervate most visceral organs, a phenomenon called __________.
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A(n) _________ binds with the receptor and causes the same response as the neurotransmitter would.
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Which of the following receptors respond to acetylcholine released from both sympathetic and parasympathetic preganglionic fibers?
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Which nervous system promotes the 'rest and digest' bodily functions?
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Which division of the autonomic nervous system stimulates contraction of the bladder wall?
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Which receptors are found on the cell membrane of cardiac muscle, smooth muscle, and glands?
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Study Notes
Autonomic Nervous System (ANS)
- ANS is not subject to voluntary control.
- Preganglionic fibers do not directly release neurotransmitters onto effector organs.
- Acetylcholine binds to nicotinic receptors within the ANS.
- Adrenergic fibers release norepinephrine, not acetylcholine.
Nervous System Divisions
- Most visceral organs receive innervation from both sympathetic and parasympathetic fibers.
- The sympathetic nervous system is responsible for the "fight or flight" response.
- Parasympathetic dominance facilitates “housekeeping” activities and “rest and digest” functions.
Neuronal Structures
- Motor neurons provoke voluntary movement in skeletal muscles.
- Somatic nervous system does not originate in the lateral horn of the thoracic spinal cord.
- Afferent neurons terminate at interneurons, while efferent neurons carry instructions from the CNS to effector organs.
Neuromuscular Junctions
- A neuromuscular junction is not a link between motor neurons but the connection between a motor neuron and skeletal muscle.
- Acetylcholine is released at the neuromuscular junction to stimulate muscle contraction.
- Acetylcholinesterase (AChE) serves to terminate the action of acetylcholine, not to keep it turned on.
Toxins and Enzymes
- Botulinum toxin does not trigger the release of ACh; it inhibits its release.
- Organophosphates irreversibly block AChE, leading to respiratory failure.
Nerve Fibers
- Sympathetic nerve fibers originate in thoracic and lumbar spinal cord regions.
- Parasympathetic postganglionic fibers are short and terminate on effector organs.
- Smooth muscle cells are innervated by sympathetic fibers.
Receptors and Responses
- Nicotinic receptors respond to acetylcholine from both ANS divisions.
- Antagonists prevent neurotransmitter effects; agonists mimic neurotransmitter actions.
- Muscarinic receptors are located on cardiac muscle, smooth muscle, and glands.
Autonomic Functions
- The parasympathetic division promotes bladder contraction.
- Stimulation of the sympathetic division increases heart rate.
- Dual innervation describes the simultaneous innervation of most visceral organs by both sympathetic and parasympathetic fibers.
Key Neurotransmitters
- Key neurotransmitters include norepinephrine and epinephrine (sympathetic) and acetylcholine (parasympathetic).
- Muscarinic receptors play a role in parasympathetic responses.
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Test your knowledge with these flashcards on Chapter 7 of Physiology. Cover key concepts of the autonomic nervous system, including neurotransmitter roles and receptor types. Perfect for students looking to reinforce their learning.
