BIOS256 W1 Lab Exercise Essay

1223 WordsNov 22, 20145 Pages
BIOS256Week1Lab1EXERCISE Mechanical Digestion in the Gastrointestinal Tract Directions: a. Click the Contents button. b. Open the Digestive System File. c. Click Animations. d. Click Mechanical Digestion in the Gastrointestinal Tract. Introduction 1. Define the gastrointestinal tract (GI). The gastrointestinal tract (GI) also known as the Alimentary Canal is one of the two groups of organs composed in the digestive system. It is defined as a continuous tube that extends from the mouth to the anus through the thoracic and abdominopelvic cavities. Organs of the GI tract includes the mouth, most of the pharynx, esophagus, stomach, small intestines, and large intestines. 2. Identify three mechanical digestion activities. a.…show more content…
Involuntary pharyngeal: stage begins as the bolus passes into the oropharynx - receptors send impulses to the deglutition center in the medulla and pons. Returning impulses cause the soft palate to move superiorly and posteriorly to close the nasopharynx. The epiglottis moves slightly inferiorly to close the glottis. Involuntary esophageal: of swallowing begins once the bolus enters the esophagus. b. Describe peristaltic movement. Also called mixing waves pass over the stomach every 15 to 25 seconds. These waves macerate food, mix it with secretions of the gastric glands, and reduce it to a soupy liquid called chyme. Stomach Peristalsis 11. a. Explain the role of stomach stretch receptors. Gastro enteric reflex: stimulates motility and secretion along the entire small intestine. Gastroileal reflex: triggers the opening of the ileocecal valve, allowing materials to pass from the small intestine into the large intestine. b. What is the function of stomach mixing waves? The waves macerate food, mix it with secretion of the gastric glands, and reduce it to a soupy liquid called chime. c. Describe the role of the parasympathetic nervous system relative to digestive movements. The PNS is responsible for stimulating digestion by increasing blood flow to the digestive tract. The PNS stimulates salivary gland secretion and increases peristalsis. This increases the

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