BPK 105 Study Guide - Final Guide: Esophagus, Pharyngeal Muscles, Medulla Oblongata
27 Apr 2018
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Module 11 - Review Questions - Part 2
3. Name and describe the three phases of deglutition (swallowing). Include the relevant
anatomy involved in each phase. [7 marks]
Swallowing, or deglutition, can be divided into three phases: the voluntary phase, the
pharyngeal phase, and the esophageal phase (figure 16.8).
- During the voluntary phase, a bolus, or mass of food, is formed in the mouth. The bolus
is pushed by the tongue against the hard palate, forcing the bolus toward the posterior
part of the mouth and into the oropharynx.
- The pharyngeal phase of swallowing is a reflex that is initiated when a bolus of food
stimulates receptors in the oropharynx. This phase of swallowing begins with the
elevation of the soft palate, which closes the passage between the nasopharynx and
oropharynx. The pharynx elevates to receive the bolus of food from the mouth. The three
pharyngeal constrictor muscles then contract in succession, forcing the food through the
pharynx. At the same time, the upper esophageal sphincter relaxes, and food is pushed
into the esophagus. As food passes through the pharynx, the vestibular and vocal folds
close, and the epiglottis is tipped posteriorly, so that the opening into the larynx is
covered. These movements prevent food from passing into the larynx.
- The esophageal phase of swallowing is responsible for moving food from the pharynx to
the stomach. Muscular contractions of the esophagus occur in peristaltic waves (figure
16.9). A wave of relaxation of the esophageal muscles precedes the bolus of food down
the esophagus, and a wave of strong contraction of the circular muscles follows and
propels the bolus through the esophagus. Gravity assists the movement of material,
especially liquids, through the esophagus. However, the peristaltic contractions that
move material through the esophagus are sufficiently forceful to allow a person to
swallow even while doing a headstand or floating in the zero-gravity environment of
space. The peristaltic contractions cause relaxation of the lower esophageal sphincter in
the esophagus as the peristaltic waves approach the stomach.
4. Describe the cephalic phase of stomach secretion. Include the function, stimulation for
release and gland of origin of each secretion. [8 marks]
The process in which stomach secretions are regulated are separated into the cephalic, gastric
and intestinal phases.
- During the celiac phase, there is an increase in stomach secretions due to the
expectancy of food that will come.
- Several factors can stimulate the regions of the medulla oblongata that have an impact
on stomach secretions.
- These factors include the smell, sight, thought and taste of food, as well as the
stimulation of particular receptors - tactile receptors in the mouth - when chewing food
and swallowing it.
Document Summary
Module 11 - review questions - part 2: name and describe the three phases of deglutition (swallowing). Include the relevant anatomy involved in each phase. Swallowing, or deglutition, can be divided into three phases: the voluntary phase, the pharyngeal phase, and the esophageal phase (figure 16. 8). During the voluntary phase, a bolus, or mass of food, is formed in the mouth. The bolus is pushed by the tongue against the hard palate, forcing the bolus toward the posterior part of the mouth and into the oropharynx. The pharyngeal phase of swallowing is a reflex that is initiated when a bolus of food stimulates receptors in the oropharynx. This phase of swallowing begins with the elevation of the soft palate, which closes the passage between the nasopharynx and oropharynx. The pharynx elevates to receive the bolus of food from the mouth. The three pharyngeal constrictor muscles then contract in succession, forcing the food through the pharynx.
