Chapter 16: Problem 5

Describe the function of the pharynx, esophagus, and lower esophageal sphincter. (pp. 372-374)

Short Answer

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Answer: The main functions of these anatomical structures in the digestive system are as follows: The pharynx facilitates the passage of food from the mouth to the esophagus during swallowing and directs food towards the esophagus and air towards the trachea. The esophagus transports swallowed food from the oral cavity to the stomach through peristalsis. The lower esophageal sphincter prevents stomach contents, including acidic gastric juices, from flowing back into the esophagus and maintains a barrier between the stomach and esophagus to protect the esophageal lining.

Step by step solution

1. Describing the function of the pharynx

The pharynx is a muscular tube that connects the nasal and oral cavities to the esophagus and larynx. Its main function is to facilitate the passage of food from the mouth to the esophagus during swallowing. It also acts as a common pathway for both food and air, ensuring that food is directed into the esophagus and air into the trachea.

2. Describing the function of the esophagus

The esophagus is a long muscular tube that connects the pharynx to the stomach, allowing the passage of food. Its primary function is to transport swallowed food from the oral cavity to the stomach through a process called peristalsis. Peristalsis is a coordinated wave-like contraction and relaxation of the esophageal muscles that propel food towards the stomach.

3. Describing the function of the lower esophageal sphincter (LES)

The lower esophageal sphincter (LES), also known as the gastroesophageal sphincter, is a muscular ring located at the junction between the esophagus and the stomach. Its primary function is to prevent stomach contents, including acidic gastric juices, from flowing back into the esophagus (a phenomenon called gastroesophageal reflux). The LES remains closed most of the time, relaxing only during swallowing to allow food to pass into the stomach. Once the food bolus has passed, the LES tightens again, maintaining a barrier between the stomach and esophagus to protect the esophageal lining from the corrosive effects of stomach acid.

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Describe the function of the pharynx, esophagus, and lower esophageal sphincter. (pp. 372-374)

Short Answer

Step by step solution

1. Describing the function of the pharynx

2. Describing the function of the esophagus

3. Describing the function of the lower esophageal sphincter (LES)

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