Nervous System Organization
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Questions and Answers

What is the primary function of the sympathetic nervous system?

  • Maintaining homeostasis during sleep
  • Promoting digestion and rest
  • Regulating blood pressure during exercise
  • Facilitating fight or flight responses (correct)
  • Which neurotransmitter is primarily released by postganglionic neurons of the sympathetic nervous system?

  • Acetylcholine
  • Dopamine
  • Serotonin
  • Noradrenaline (correct)
  • Where are most parasympathetic preganglionic neurons located?

  • In discrete ganglia near targets
  • Throughout the entire nervous system
  • In the cranial nerve nuclei and sacral spinal cord (correct)
  • In the spinal cord only
  • What is the primary role of the enteric nervous system?

    <p>Controlling gut activity and digestion</p> Signup and view all the answers

    What distinguishes parasympathetic preganglionic neurons from sympathetic preganglionic neurons?

    <p>Parasympathetic neurons have long, lightly myelinated axons</p> Signup and view all the answers

    Which of the following statements about postganglionic sympathetic neurons is true?

    <p>They project mainly to smooth muscles, glands, or cardiac muscles</p> Signup and view all the answers

    What prepares the body for maintenance activities and rest?

    <p>Parasympathetic nervous system</p> Signup and view all the answers

    Which cranial nerve is associated with parasympathetic preganglionic neurons?

    <p>Cranial Nerve X</p> Signup and view all the answers

    What type of axons do postganglionic parasympathetic neurons have?

    <p>Short, non-myelinated axons</p> Signup and view all the answers

    Which pathway do preganglionic sympathetic axons take to reach postganglionic neurons?

    <p>Through the white ramus communicans</p> Signup and view all the answers

    What is the primary role of visceral sensory afferents in the autonomic nervous system?

    <p>To send sensory information back to the spinal cord</p> Signup and view all the answers

    Which of the following adrenergic receptor types induces slow-acting responses in sympathetic targets?

    <p>Various types based on intracellular signaling pathways</p> Signup and view all the answers

    What is the primary function of the Submucosal (Meissner's) plexus in the enteric nervous system?

    <p>Managing secretions and blood flow in the gut</p> Signup and view all the answers

    Which factors influence the physiological effects of acetylcholine in the autonomic nervous system?

    <p>The types of receptors it binds to</p> Signup and view all the answers

    What is the primary role of the Myenteric (Auerbach's) plexus in the enteric nervous system?

    <p>To facilitate peristalsis and gut movements</p> Signup and view all the answers

    Preganglionic neurons in the intermediolateral horn primarily communicate with which structure to reach postganglionic neurons?

    <p>Sympathetic chain</p> Signup and view all the answers

    What type of neurons in the myenteric plexus are responsible for measuring the degree of stretch in smooth muscles?

    <p>Sensory neurons</p> Signup and view all the answers

    Which type of neurons in the submucosal plexus measure the chemical composition of the lumen?

    <p>Sensory neurons</p> Signup and view all the answers

    Which neurons are primarily involved in coordinating peristaltic movement of the gut?

    <p>Excitatory and inhibitory visceromotor neurons</p> Signup and view all the answers

    What role do interneurons play in the enteric nervous system?

    <p>They connect sensory and motor neurons.</p> Signup and view all the answers

    Which autonomic components provide regulatory input to the enteric nervous system?

    <p>Parasympathetic and sympathetic neurons</p> Signup and view all the answers

    Where do visceral sensory signals from internal organs primarily travel to within the brainstem?

    <p>Nucleus of the solitary tract (NST)</p> Signup and view all the answers

    What is one of the main functions of the nucleus of the solitary tract (NST)?

    <p>Local reflex activity and higher brain integration</p> Signup and view all the answers

    What type of neurons are involved in activating preganglionic and postganglionic neurons for reflex activity?

    <p>Brainstem reticular formation neurons</p> Signup and view all the answers

    What effect does the sympathetic nervous system have on blood flow?

    <p>Blood flow is redistributed to striated and cardiac muscle.</p> Signup and view all the answers

    Which statement accurately describes the neurotransmitter released by postganglionic parasympathetic neurons?

    <p>They exclusively release acetylcholine.</p> Signup and view all the answers

    Where are the majority of preganglionic neurons of the parasympathetic nervous system located?

    <p>In the visceral efferent motor nuclei of cranial nerves.</p> Signup and view all the answers

    What is a characteristic of the postganglionic neurons in the sympathetic nervous system?

    <p>They are long and non-myelinated.</p> Signup and view all the answers

    Which function is primarily associated with the enteric nervous system?

    <p>Controlling gut motility and secretion.</p> Signup and view all the answers

    What is the role of the postganglionic neurons in the parasympathetic nervous system?

    <p>They are usually found in discrete ganglia close to their targets.</p> Signup and view all the answers

    What primary neurotransmitter do most postganglionic sympathetic neurons release?

    <p>Noradrenaline</p> Signup and view all the answers

    What is the main role of sensory neurons in the myenteric plexus?

    <p>To measure the degree of stretch in smooth muscles</p> Signup and view all the answers

    How do secretomotor neurons function within the enteric nervous system?

    <p>They promote mucous release into the lumen.</p> Signup and view all the answers

    Which of the following accurately describes the role of the nucleus of the solitary tract (NST)?

    <p>It integrates visceral sensory information for higher brain functions.</p> Signup and view all the answers

    Which neurotransmitter is NOT typically used in the enteric nervous system?

    <p>Norepinephrine</p> Signup and view all the answers

    What type of neurons primarily relay visceral sensory information to the dorsal root ganglion?

    <p>Visceral sensory DRG neurons</p> Signup and view all the answers

    Which of the following statements about the enteric nervous system is true?

    <p>It operates independently yet receives regulatory input from autonomic neurons.</p> Signup and view all the answers

    What is the function of interneurons in the enteric nervous system?

    <p>They connect sensory neurons to motor neurons.</p> Signup and view all the answers

    Which type of neurons directly innervate the visceral sensory division of the NST?

    <p>Visceral sensory neurons from cranial nerves IX and X</p> Signup and view all the answers

    What role do adrenergic receptors play in sympathetic targets?

    <p>They activate intracellular signaling pathways for slow-acting and prolonged responses.</p> Signup and view all the answers

    Which structure primarily houses the cell bodies of preganglionic sympathetic neurons?

    <p>Intermediolateral horn (IML)</p> Signup and view all the answers

    What are the two main types of acetylcholine receptors found in the autonomic nervous system?

    <p>Nicotinic and muscarinic receptors</p> Signup and view all the answers

    What axonal characteristics distinguish postganglionic sympathetic neurons?

    <p>Short, non-myelinated axons</p> Signup and view all the answers

    Where do preganglionic sympathetic axons synapse if they bypass the sympathetic chain?

    <p>In prevertebral ganglia</p> Signup and view all the answers

    What function does the Myenteric plexus perform in the enteric nervous system?

    <p>Controls gut movements like peristalsis</p> Signup and view all the answers

    What type of axons are carried by visceral sensory afferents from organs to the spinal cord?

    <p>Lightly myelinated axons that carry sensory information</p> Signup and view all the answers

    What influences the physiological effects of acetylcholine in the autonomic nervous system?

    <p>The type of acetylcholine receptors present on target cells</p> Signup and view all the answers

    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.
    • 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.
    • 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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    Autonomic Nervous System PDF

    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.

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