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Chapter 12: Efferent Division: Autonomic and Somatic Motor Control

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Terms in this set (20)

  • What are the two divisions of the efferent peripheral nervous system?
    The two divisions are the autonomic nervous system (ANS) and the somatic motor system.
  • What are the two divisions of the autonomic nervous system (ANS)?
    The two divisions are the sympathetic nervous system (SNS) and the parasympathetic nervous system (pSNS).
  • What are the primary functions of the sympathetic and parasympathetic divisions?
    The SNS prepares the body for fight or flight responses, while the pSNS promotes rest and digest activities.
  • Where are autonomic nervous system (ANS) control centers located?
    ANS control centers are located in the brainstem, hypothalamus, and spinal cord.
  • What is the general pattern of ANS reflexes and which brain parts influence them?
    ANS reflexes involve sensory input to integrating centers that send output via autonomic pathways; influenced by the hypothalamus, limbic system, and cerebral cortex.
  • Give examples of antagonistic control by SNS and pSNS.
    Examples include heart rate: SNS increases it, pSNS decreases it; pupil diameter: SNS dilates, pSNS constricts.
  • What is tonic control by the sympathetic nervous system?
    Tonic control is the continuous baseline activity of the SNS that regulates functions like blood vessel diameter.
  • Define pre-ganglionic neuron, post-ganglionic neuron, and ganglion in the ANS pathway.
    Pre-ganglionic neuron originates in CNS and synapses in a ganglion; ganglion is a cluster of neuron cell bodies outside CNS; post-ganglionic neuron extends from ganglion to effector.
  • How do SNS and pSNS differ in pathway origin and ganglion location?
    SNS pathways originate in the thoracolumbar spinal cord with ganglia near the spinal cord; pSNS originates in the brainstem or sacral spinal cord with ganglia near or in the target organ.
  • Compare pre-ganglionic and post-ganglionic axon lengths in SNS and pSNS.
    SNS has short pre-ganglionic and long post-ganglionic axons; pSNS has long pre-ganglionic and short post-ganglionic axons.
  • What neurotransmitters and receptors are used at ganglionic synapses in SNS and pSNS?
    Both SNS and pSNS use acetylcholine (ACh) at ganglionic synapses, acting on nicotinic cholinergic receptors.
  • What neurotransmitters and receptors are used at neuroeffector junctions in SNS and pSNS?
    SNS post-ganglionic neurons release norepinephrine acting on adrenergic receptors; pSNS post-ganglionic neurons release acetylcholine acting on muscarinic cholinergic receptors.
  • What are the effectors of the autonomic nervous system?
    Effectors include smooth muscle, cardiac muscle, and glands.
  • Describe the structure of the neuroeffector synapse and define a varicosity.
    Neuroeffector synapses have varicosities, which are swollen regions along post-ganglionic axons that release neurotransmitters over a wide area.
  • How does the neuroeffector synapse differ from a neural synapse or neuromuscular junction?
    Neuroeffector synapses lack a specialized synaptic cleft and release neurotransmitters diffusely from varicosities, unlike the precise synapses in neurons or neuromuscular junctions.
  • What are adrenergic and cholinergic receptors?
    Adrenergic receptors bind norepinephrine and epinephrine; cholinergic receptors bind acetylcholine. Both have multiple subtypes with different effects.
  • Describe the structure and function of the adrenal medulla.
    The adrenal medulla contains chromaffin cells that secrete epinephrine and norepinephrine into the blood; it is innervated by the SNS.
  • What is a chromaffin cell?
    A chromaffin cell is a modified post-ganglionic sympathetic neuron in the adrenal medulla that secretes catecholamines into the bloodstream.
  • Is the adrenal medulla innervated by the SNS or pSNS?
    The adrenal medulla is innervated by the sympathetic nervous system (SNS).
  • How do somatic motor pathways differ from autonomic efferent pathways?
    Somatic motor pathways have a single neuron from CNS to skeletal muscle, releasing acetylcholine at a neuromuscular junction; autonomic pathways have two neurons with ganglia and varicosities.