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Parasympathetic Nervous System quiz #1

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  • What are the primary physiological effects of the parasympathetic nervous system on the heart, lungs, gastrointestinal tract, bladder, and pupils?
    The parasympathetic nervous system decreases heart rate, constricts bronchioles in the lungs, increases gastrointestinal activity (motility and secretion), promotes urination by contracting bladder smooth muscle and relaxing the sphincter, and constricts pupils to optimize close vision.
  • Why is the parasympathetic nervous system referred to as the craniosacral division, and which nerve provides most of its innervation?
    It is called the craniosacral division because its fibers arise from the brainstem (cranial region) and sacral region of the spinal cord. The vagus nerve (cranial nerve X) provides about 90% of parasympathetic innervation.
  • Describe the arrangement and relative lengths of preganglionic and postganglionic fibers in the parasympathetic nervous system.
    Preganglionic fibers in the parasympathetic nervous system are long and extend from the CNS to synapse within or very near the target organs (in terminal ganglia), while postganglionic fibers are short, allowing for quick responses in the target organs.
  • What effect does the parasympathetic nervous system have on heart rate and bronchioles?
    It decreases heart rate and constricts the bronchioles to conserve energy.
  • How does the parasympathetic nervous system affect the gastrointestinal tract?
    It increases movement and secretion in the gastrointestinal tract and relaxes sphincters to promote digestion.
  • What changes does the parasympathetic nervous system cause in the bladder to promote urination?
    It contracts the smooth muscle of the bladder and relaxes the sphincter, making urination easier.
  • Why does the parasympathetic nervous system cause pupil constriction?
    Pupil constriction optimizes close vision, which is useful in a relaxed state when scanning for danger is unnecessary.
  • Why is the parasympathetic nervous system called the craniosacral division?
    Because its fibers arise from the brainstem (cranial region) and the sacral region of the spinal cord.
  • Which nerve provides the majority of parasympathetic innervation, and what percentage does it account for?
    The vagus nerve (cranial nerve X) provides about 90% of parasympathetic innervation.
  • Describe the relative lengths and synapse locations of preganglionic and postganglionic fibers in the parasympathetic nervous system.
    Preganglionic fibers are long and synapse within or very near the target organs, while postganglionic fibers are short.
  • What physiological changes occur when the parasympathetic nervous system is stimulated?
    Stimulation of the parasympathetic nervous system results in decreased heart rate, bronchiole constriction, increased gastrointestinal activity, promotion of urination, and pupil constriction for close vision.
  • Which nervous system division is responsible for decreasing heart rate?
    The parasympathetic nervous system is responsible for decreasing heart rate.
  • What are the main functions of the parasympathetic nervous system?
    The main functions of the parasympathetic nervous system are energy conservation, restoration, promoting rest and digest activities, decreasing heart rate, increasing gastrointestinal activity, promoting urination, and constricting pupils for close vision.
  • How does activation of the parasympathetic nervous system affect the heart rate?
    Activation of the parasympathetic nervous system decreases heart rate.
  • What effect does the parasympathetic nervous system have on the gastrointestinal tract?
    The parasympathetic nervous system increases movement and secretion in the gastrointestinal tract and relaxes sphincters to promote digestion.
  • Describe the structural organization of the parasympathetic nervous system.
    The parasympathetic nervous system is also called the craniosacral division, with fibers arising from the brainstem and sacral region. Preganglionic fibers are long and synapse in ganglia within or very close to target organs, while postganglionic fibers are short.
  • Which cranial nerve provides the majority of parasympathetic innervation, and what is its significance?
    The vagus nerve (cranial nerve 10) provides about 90% of parasympathetic innervation, making it crucial for the system's function.