Swallowing (deglutition) from Anatomy & Physiology Online

Summary

This video explains the process of swallowing (deglutition), where food moves from the mouth to the stomach through a series of controlled muscle contractions. The process involves three stages: the voluntary phase, where the tongue pushes food into the pharynx; the involuntary phase, where the bolus moves through the throat and esophagus with the help of brain signals; and the esophageal phase, where peristalsis propels the bolus into the stomach. The video also covers the role of saliva in breaking down food and preventing it from entering the respiratory tract, ensuring safe and efficient digestion.

Takeaways

• 😀 Swallowing (deglutition) is the process by which food passes from the mouth to the stomach.
• 😀 The swallowing process involves both voluntary and involuntary muscle contractions, coordinated by the nervous system.
• 😀 Food is mechanically broken down in the mouth by chewing (mastication) before being swallowed.
• 😀 The salivary glands secrete enzymes like lingual lipase and salivary amylase to begin the chemical breakdown of food.
• 😀 Saliva also helps bind food particles together to form a bolus, which is easier to swallow.
• 😀 The swallowing process occurs in three stages: oral (voluntary), pharyngeal (involuntary), and esophageal (peristalsis-driven).
• 😀 In the oral phase, the tongue pushes the bolus from the mouth into the oropharynx.
• 😀 The pharyngeal phase involves involuntary movements to push the bolus through the pharynx, with the airway being protected by the epiglottis and soft palate.
• 😀 In the esophageal phase, peristalsis pushes the bolus down the esophagus to the stomach.
• 😀 The lower esophageal sphincter relaxes to allow the bolus into the stomach, preventing backflow into the esophagus.

Q & A

What is deglutition, and how does it relate to the digestive process?

Deglutition is the process by which food passes from the mouth to the stomach. It involves both voluntary and involuntary muscle contractions and is essential for the movement of food into the digestive system.

How does chewing or mastication contribute to digestion?

Chewing, or mastication, mechanically breaks down food in the mouth, making it easier to swallow and aiding in the overall digestion process by increasing the surface area of food particles.

What enzymes are secreted by the salivary glands, and what role do they play in digestion?

The salivary glands secrete lingual lipase and salivary amylase. Lingual lipase helps break down fats, while salivary amylase begins the chemical breakdown of starches into simpler sugars.

What is the function of saliva in the swallowing process?

Saliva's water content helps bind food particles together to form a bolus, which is easier to swallow. It also contains enzymes that initiate the breakdown of food, particularly carbohydrates.

What are the three stages of swallowing?

The three stages of swallowing are the voluntary phase (oral transit phase), the pharyngeal phase (involuntary movement through the pharynx), and the esophageal phase (involuntary movement through the esophagus).

What happens during the voluntary phase of swallowing?

During the voluntary phase, the tongue moves upwards and backwards against the hard and soft palates to push the bolus into the oropharynx.

How does the body prevent food from entering the respiratory tract during swallowing?

The body prevents food from entering the respiratory tract by closing off the nasopharynx with the soft palate and uvula, while the epiglottis seals off the larynx.

What is the role of the upper esophageal sphincter in swallowing?

The upper esophageal sphincter relaxes to allow the bolus to move from the pharynx into the esophagus and contracts afterward to prevent backflow into the pharynx.

What is peristalsis, and how does it assist in swallowing?

Peristalsis is a series of involuntary, wavelike muscle contractions in the esophagus that help move the bolus downward toward the stomach.

How does the lower esophageal sphincter function during swallowing?

The lower esophageal sphincter relaxes as the bolus approaches the end of the esophagus, allowing the bolus to enter the stomach, and then contracts to prevent backflow into the esophagus.