Chapter 17 the autonomic nervous system suggested Lecture Outline


COMPARISON OF SOMATIC AND AUTONOMIC NERVOUS SYSTEMS



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COMPARISON OF SOMATIC AND AUTONOMIC NERVOUS SYSTEMS

  • The somatic nervous system contains both sensory and motor neurons.

  • The somatic sensory neurons receive input from receptors of the special and somatic senses.

  • These sensations are consciously perceived.

  • Somatic motor neurons innervate skeletal muscle to produce conscious, voluntary movements.

  • The effect of a motor neuron is always excitation.

  • The autonomic nervous system contains both autonomic sensory and motor neurons.

  • Autonomic sensory neurons are associated with interoceptors.

  • Autonomic sensory input is not consciously perceived.

  • The ANS also receives sensory input from somatic senses and special sensory neurons.

  • The autonomic motor neurons regulate visceral activities by either increasing (exciting) or decreasing (inhibiting) ongoing activities of cardiac muscle, smooth muscle, and glands.

  • Most autonomic responses can not be consciously altered or suppressed.

  • All autonomic motor pathways consists of two motor neurons in series (Figure 17.1).

  • The axon of the first motor neuron of the ANS extends from the CNS and synapses in a ganglion with the second neuron.

  • The second neuron synapses on an effector. Preganglionic fibers release acetylcholine and postganglionic fibers release acetylcholine or norepinephrine.

  • The output (efferent) part of the ANS is divided into two principal parts: the sympathetic and the parasympathetic divisions. Organs that receive impulses from both sympathetic and parasympathetic fibers are said to have dual innervation.

  • Table 17.1 summarizes the similarities and differences between the somatic and autonomic nervous systems.




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