22.4C: Esophagus
The esophagus is a muscular tube that moves food from the pharynx to the stomach via peristalsis.
- Describe the role of the esophagus in digestion
Key Points
- The esophagus is the muscular tube that moves food material from the pharynx to the stomach via waves of muscle movement known as peristalsis. The junction between the esophagus and the stomach is known as the gastroesophageal junction or GE junction.
- The entry to the esophagus opens only when swallowing or vomiting due to specialized muscles that control the opening.
Key Terms
- esophagus : The esophagus is an organ in vertebrates that consists of a muscular tube through which food passes from the pharynx to the stomach.
- peristalsis : The rhythmic, wave-like contraction of both longitudinal and circular smooth muscle fibers within the digestive tract that forces food through it.
- mucus : A slippery secretion from the lining of the mucous membranes.
EXAMPLES
Swallowing is a voluntary act that utilizes the muscles of the mouth and tongue to push food into the esophagus. Once food material is pushed into the throat, or pharynx, the trachea (windpipe) is blocked by a flap of tissue known as the epiglottis to prevent the aspiration of food. Food then moves down the esophageal tube through waves of muscle movement, or peristalsis, until it reaches the stomach.
The esophagus is an organ in vertebrates that consists of a muscular tube through which food passes from the pharynx to the stomach. It is a major component of the upper digestive system.
Esophagus: The location of the esophagus within the greater digestive system in humans.
The word esophagus is derived from the Latin œsophagus, which derives from the Greek word oisophagos, meaning entrance for eating. It is lined with mucus to aid in the passage of food.
Length and Location
In humans the esophagus is continuous with the laryngeal part of the pharynx within the neck, and it passes through the thorax diaphragm and into abdomen to reach the cardiac orifice of the stomach. It is usually about 10–50 cm long depending on an individual’s height. Due to the inferior pharyngeal constrictor muscle, the entry to the esophagus opens only when swallowing or vomiting.
Layers of Tissue
The esophageal tube in humans is comprised of two main layers of smooth muscle, though striated muscle comprises the tube near the pharynx. This combination of muscle tissue allows peristalsis to push food downward, and aids in regurgitation at the pharynx.
The innermost layer of smooth muscle is arranged in a series of concentric rings, while the outermost layer is arranged longitudinally.
In much of the gastrointestinal tract, smooth muscles contract in sequence to produce a peristaltic wave which forces a ball of food (called a bolus) from the pharynx to the stomach.
The Gastroesophageal Junction
The junction between the esophagus and the stomach (the gastroesophageal junction or GE junction) is not actually considered a valve in the anatomical sense, although it is sometimes called the cardiac sphincter.
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