Deglutination In The Columbian Exchange

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Bio-227 FG Dr. Falkhoury Truman College March 6, 2008 Take my hand as I walk you into the mouth of the primordial man who is about to eat a meal rich in fat, proteins, and carbohydrates. Before him lies the stripped carcass of a wildebeest. He will take his primitive hand tool, crack open the bone, and roast the marrow over a brush fire. He also consumes a handful of lentils, and quenches his thirst by suckingthe carbohydrates out of a moist tuber. In between gulps of this nutritious meal, let us sneak in to his cavernous mouth. As we glide between his lips, which are pulled apart by his orbicularus oris, allow me to narrate our marvelous journey… through the digestive system. Digestion, a pertinent component of survival,…show more content…
This is the first of the three phases of deglutination. The three stages of deglutination are the buccal stage, the pharyngeal stage, and the esophageal stage. The buccal stage is voluntary, while the pharyngeal and esophageal stages are involuntary. The pharyngeal-esophageal stage of swallowing is controlled by the swallowing center in the brain stem. During this stage the tongue blocks the opening to the mouth, the uvula blocks off the opening to the nasopharynx, the larynx rise and the epiglottis covers its opening into the respiratory tract, and the upper esophageal sphincter relaxes to allow the bolus to pass through. Peristaltic contractions propel the bolus through the pharynx and into the esophagus. As food reaches the end of the esophagus the lower esophageal sphincter relaxes due to reflex and then closes tightly once the food has entered the…show more content…
Here, we encounter smooth walls of muscle and thick mucosa, where there are no villi or microvilli. No more chemical digestion will occur will only occur with the aid of bacteria, who synthesize vitamins, water and some electrolytes will be absorbed along with the vitamins. Here, the goblet cells are numerous and the crypts abundant. Goblet cells secrete mucus, and so the mucosa is thicker, aiding in the passage of feces. The thick layer of mucus protects intestinal walls from acids and gases released by bacteria. In the large intestine, remaining water from digestion is absorbed by the mucosal cells through
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