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What is the primary function of the sympathetic nervous system?
What is the primary function of the sympathetic nervous system?
Which neurotransmitter is primarily released by postganglionic neurons of the sympathetic nervous system?
Which neurotransmitter is primarily released by postganglionic neurons of the sympathetic nervous system?
Where are most parasympathetic preganglionic neurons located?
Where are most parasympathetic preganglionic neurons located?
What is the primary role of the enteric nervous system?
What is the primary role of the enteric nervous system?
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What distinguishes parasympathetic preganglionic neurons from sympathetic preganglionic neurons?
What distinguishes parasympathetic preganglionic neurons from sympathetic preganglionic neurons?
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Which of the following statements about postganglionic sympathetic neurons is true?
Which of the following statements about postganglionic sympathetic neurons is true?
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What prepares the body for maintenance activities and rest?
What prepares the body for maintenance activities and rest?
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Which cranial nerve is associated with parasympathetic preganglionic neurons?
Which cranial nerve is associated with parasympathetic preganglionic neurons?
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What type of axons do postganglionic parasympathetic neurons have?
What type of axons do postganglionic parasympathetic neurons have?
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Which pathway do preganglionic sympathetic axons take to reach postganglionic neurons?
Which pathway do preganglionic sympathetic axons take to reach postganglionic neurons?
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What is the primary role of visceral sensory afferents in the autonomic nervous system?
What is the primary role of visceral sensory afferents in the autonomic nervous system?
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Which of the following adrenergic receptor types induces slow-acting responses in sympathetic targets?
Which of the following adrenergic receptor types induces slow-acting responses in sympathetic targets?
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What is the primary function of the Submucosal (Meissner's) plexus in the enteric nervous system?
What is the primary function of the Submucosal (Meissner's) plexus in the enteric nervous system?
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Which factors influence the physiological effects of acetylcholine in the autonomic nervous system?
Which factors influence the physiological effects of acetylcholine in the autonomic nervous system?
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What is the primary role of the Myenteric (Auerbach's) plexus in the enteric nervous system?
What is the primary role of the Myenteric (Auerbach's) plexus in the enteric nervous system?
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Preganglionic neurons in the intermediolateral horn primarily communicate with which structure to reach postganglionic neurons?
Preganglionic neurons in the intermediolateral horn primarily communicate with which structure to reach postganglionic neurons?
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What type of neurons in the myenteric plexus are responsible for measuring the degree of stretch in smooth muscles?
What type of neurons in the myenteric plexus are responsible for measuring the degree of stretch in smooth muscles?
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Which type of neurons in the submucosal plexus measure the chemical composition of the lumen?
Which type of neurons in the submucosal plexus measure the chemical composition of the lumen?
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Which neurons are primarily involved in coordinating peristaltic movement of the gut?
Which neurons are primarily involved in coordinating peristaltic movement of the gut?
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What role do interneurons play in the enteric nervous system?
What role do interneurons play in the enteric nervous system?
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Which autonomic components provide regulatory input to the enteric nervous system?
Which autonomic components provide regulatory input to the enteric nervous system?
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Where do visceral sensory signals from internal organs primarily travel to within the brainstem?
Where do visceral sensory signals from internal organs primarily travel to within the brainstem?
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What is one of the main functions of the nucleus of the solitary tract (NST)?
What is one of the main functions of the nucleus of the solitary tract (NST)?
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What type of neurons are involved in activating preganglionic and postganglionic neurons for reflex activity?
What type of neurons are involved in activating preganglionic and postganglionic neurons for reflex activity?
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What effect does the sympathetic nervous system have on blood flow?
What effect does the sympathetic nervous system have on blood flow?
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Which statement accurately describes the neurotransmitter released by postganglionic parasympathetic neurons?
Which statement accurately describes the neurotransmitter released by postganglionic parasympathetic neurons?
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Where are the majority of preganglionic neurons of the parasympathetic nervous system located?
Where are the majority of preganglionic neurons of the parasympathetic nervous system located?
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What is a characteristic of the postganglionic neurons in the sympathetic nervous system?
What is a characteristic of the postganglionic neurons in the sympathetic nervous system?
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Which function is primarily associated with the enteric nervous system?
Which function is primarily associated with the enteric nervous system?
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What is the role of the postganglionic neurons in the parasympathetic nervous system?
What is the role of the postganglionic neurons in the parasympathetic nervous system?
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What primary neurotransmitter do most postganglionic sympathetic neurons release?
What primary neurotransmitter do most postganglionic sympathetic neurons release?
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What is the main role of sensory neurons in the myenteric plexus?
What is the main role of sensory neurons in the myenteric plexus?
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How do secretomotor neurons function within the enteric nervous system?
How do secretomotor neurons function within the enteric nervous system?
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Which of the following accurately describes the role of the nucleus of the solitary tract (NST)?
Which of the following accurately describes the role of the nucleus of the solitary tract (NST)?
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Which neurotransmitter is NOT typically used in the enteric nervous system?
Which neurotransmitter is NOT typically used in the enteric nervous system?
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What type of neurons primarily relay visceral sensory information to the dorsal root ganglion?
What type of neurons primarily relay visceral sensory information to the dorsal root ganglion?
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Which of the following statements about the enteric nervous system is true?
Which of the following statements about the enteric nervous system is true?
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What is the function of interneurons in the enteric nervous system?
What is the function of interneurons in the enteric nervous system?
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Which type of neurons directly innervate the visceral sensory division of the NST?
Which type of neurons directly innervate the visceral sensory division of the NST?
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What role do adrenergic receptors play in sympathetic targets?
What role do adrenergic receptors play in sympathetic targets?
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Which structure primarily houses the cell bodies of preganglionic sympathetic neurons?
Which structure primarily houses the cell bodies of preganglionic sympathetic neurons?
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What are the two main types of acetylcholine receptors found in the autonomic nervous system?
What are the two main types of acetylcholine receptors found in the autonomic nervous system?
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What axonal characteristics distinguish postganglionic sympathetic neurons?
What axonal characteristics distinguish postganglionic sympathetic neurons?
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Where do preganglionic sympathetic axons synapse if they bypass the sympathetic chain?
Where do preganglionic sympathetic axons synapse if they bypass the sympathetic chain?
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What function does the Myenteric plexus perform in the enteric nervous system?
What function does the Myenteric plexus perform in the enteric nervous system?
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What type of axons are carried by visceral sensory afferents from organs to the spinal cord?
What type of axons are carried by visceral sensory afferents from organs to the spinal cord?
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What influences the physiological effects of acetylcholine in the autonomic nervous system?
What influences the physiological effects of acetylcholine in the autonomic nervous system?
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Study Notes
Nervous System Organization
- The autonomic nervous system (ANS) maintains homeostasis, despite external variations.
- It controls internal body functions without conscious input.
Sympathetic Nervous System
- Function: Prepares the body for stressful situations ("fight-or-flight").
- Responses: Increased heart rate, dilated pupils, diverted blood flow away from non-essential organs to muscles, increased respiration, increased glycogen breakdown.
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Mechanism: Two-neuron relay:
- Preganglionic neurons are short, lightly myelinated, and release acetylcholine (ACh).
- Postganglionic neurons are long, non-myelinated and for the most part, release noradrenaline (90% of them); a small percentage of them release ACh.
- Postganglionic neurons also project to targets like smooth muscle, glands, and cardiac muscles.
Parasympathetic Nervous System
- Function: Prepares the body for rest and digestion ("rest-and-digest").
- Responses: Decreased heart rate, constricted pupils, increased digestive functions, slowed respiration.
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Mechanism: Two-neuron relay:
- Preganglionic neurons are long, lightly myelinated, and release acetylcholine (ACh).
- Postganglionic neurons are short, non-myelinated, and release acetylcholine (ACh).
- Some parasympathetic preganglionic neurons are located in cranial nerves.
Enteric Nervous System (ENS)
- Function: Regulates the activity of the gastrointestinal (GI) tract, including digestion, secretion, and motility.
- Location: Embedded in the lining of the gastrointestinal (GI) tract.
- Relationship to other systems: Largely independent of the brain and spinal cord, but receives input from parasympathetic (vagus nerve) and sympathetic branches.
Sympathetic Nervous System Relay
- Preganglionic: Short, lightly myelinated axons, releasing acetylcholine (ACh)
- Postganglionic: Long, non-myelinated axons, mostly releasing noradrenaline (90%) or acetylcholine (10%).
Parasympathetic Nervous System
- Preganglionic: Long, lightly myelinated axons, releasing acetylcholine (ACh)
- Postganglionic: Short, non myelinated axons,releasing acetylcholine (ACh).
Autonomic Receptors
- Adrenergic receptors: Effects of adrenaline/noradrenaline depend on the receptor type, inducing slow-acting and prolonged responses. Effects depend on which G protein they are coupled with. Multiple receptor types mediate acetylcholine's effects.
- Nicotinic receptors: Found on postganglionic neurons, inducing quick, brief responses.
- Muscarinic receptors: On target tissues, inducing a prolonged effect.
Autonomic Nervous System Regulation
- Sensory feedback from target organs influences ANS activity.
- Visceral sensory neurons send information to the nucleus of the solitary tract (NST) in the medulla.
- Brainstem and higher brain centers coordinate ANS function for reflex and higher-level control.
- Central sensory neurons (afferents) from cranial nerves IX and X directly connect to the nucleus of the solitary tract (NST) in the medulla. Visceral sensory neurons from spinal nerves (DRG neurons) indirectly connect to the NST.
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Description
Explore the intricacies of the nervous system, focusing on the autonomic nervous system's role in maintaining homeostasis. Understand the functions and mechanisms of both the sympathetic and parasympathetic nervous systems as they respond to stress and relaxation.