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Chapter 24-3

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Terms in this set (28)

  • Pharynx
    An anatomical space serving as a common passageway for solid food, liquid, and air.
  • Three parts of the pharynx
    Nasopharynx, oropharynx, and laryngopharynx.
  • Epithelium type lining the pharynx
    Stratified squamous epithelium.
  • Role of pharyngeal muscles in swallowing
    Work with oral cavity muscles to start swallowing and push the bolus into the esophagus.
  • Esophagus function
    A hollow muscular tube that actively propels ingested food to the stomach.
  • Length and width of the esophagus
    Approximately 25 cm long and 2 cm wide at its widest point.
  • Starting point of the esophagus
    Posterior to the cricoid cartilage at vertebra C6.
  • Histology of esophageal mucosa
    Nonkeratinized stratified squamous epithelium with a muscularis mucosae layer of smooth muscle.
  • Function of esophageal submucosa folds
    Allow expansion to accommodate a large bolus during swallowing.
  • Muscle layers of the esophagus
    Inner circular and outer longitudinal layers; superior third is skeletal muscle, middle third mixed, inferior third smooth muscle.
  • Adventitia of the esophagus
    Connective tissue layer anchoring the esophagus to the posterior body wall.
  • Esophageal innervation
    Parasympathetic and sympathetic fibers from the esophageal plexus.
  • Function of muscle tone in the superior esophagus
    Prevents air from entering the esophagus.
  • Role of the lower esophageal sphincter
    Prevents reflux of stomach contents into the esophagus by remaining contracted.
  • Phases of deglutition (swallowing)
    Buccal phase, pharyngeal phase, and esophageal phase.
  • Key action in the buccal phase
    Compression of the bolus against the hard palate and tongue retraction to push it into the oropharynx.
  • Pharyngeal phase main events
    Bolus contacts palatal arches, larynx elevates, epiglottis folds to protect airway, and nasopharynx is sealed.
  • Duration of the esophageal phase
    Less than a second; bolus is pushed by peristaltic waves into the stomach.
  • Muscles that elevate the larynx during swallowing
    Palatopharyngeus and stylopharyngeus muscles.
  • Function of pharyngeal constrictor muscles
    Push the bolus toward and into the esophagus.
  • Swallowing reflex initiation
    Triggered by tactile receptors on the palatal arches and uvula stimulated by the bolus.
  • Swallowing center location and nerve involvement
    Located in the medulla oblongata; receives input via trigeminal (V) and glossopharyngeal (IX) nerves.
  • Primary peristaltic waves control
    Coordinated by afferent and efferent fibers in glossopharyngeal (IX) and vagus (X) nerves.
  • Typical time for a bolus to travel the esophagus
    About 9 seconds; liquids move faster, dry boluses slower.
  • Secondary peristaltic waves
    Local reflexes triggered by sensory receptors in the esophageal walls to clear remaining bolus.
  • How the glottis is protected during swallowing
    Epiglottis bends over the glottis, and the glottis closes to prevent food entry.
  • Effect of swallowing on respiration
    Respiratory centers are inhibited and breathing stops briefly during swallowing.
  • Frequency of swallowing in a day
    Approximately 2400 times daily.