Question

gastric motility (explain with three types of movement)​

Answer 1

Answer:

Explanation:

The swallowing or deglutition that occurs in the mouth and upper part of the esophagus can be divided into 3 phases:

1. Voluntary Phase

A bolus, or mass of food, is formed in the mouth

The bolus pushed by the tongue against the hard palate, forcing the bolus toward the posterior part of the mouth and into the oropharynx

2. Pharyngeal Phase

Is a reflex that is initiated when a bolus of food stimulates tactile receptors in the oropharynx

The soft palate is elevated, which closes the passage between the nasopharynx and oropharynx (the vestibular folds and vocal cords close and the epiglottis is tipped posteriorly so that it covers the opening into the larynx)

The pharynx elevates to receive the bolus of food from the mouth

Three pharyngeal constrictor muscles then contract in successsion, forcing the food through the pharynx. At the same time the upper esophageal spincter relaxes, and food is pushed into the esophagus

3. Esophageal Phase

This phase takes about 8 seconds and moves food from the pharynx to the stomach

Muscular contractions collectively called peristalsis occur in the walls of the esophagus

The circular esophageal muscles ahead of the bolus of food relaxes, allowing the digestive tract to expand

A wave of strong contractions of the circular muscles behind the bolus of food occurs

The bolus is propeled through the esophagus

The lower esophageal sphincter in the esophagus relaxes as the peristaltic waves approach the stomach

The presence of food in the esophagus stimulates the enteric plexus, which controls peristalsis through local reflexes;

Motor impulses pass along the efferent fibers of the vagus nerve (CN X) to the striated and smooth muscles within the esophagus, which stimulates their peristaltic contractions