Chapter 3: Organs of the Alimentary Canal

Question 1

When does digestion begin?

Answer 1

Digestion begins even before food enters your mouth.

Question 2

What can stimulate the secretion of saliva?

Answer 2

The smell or sight of food that appeals to you can stimulate the secretion of saliva.

Question 3

What glands are responsible for secreting saliva in the mouth?

Answer 3

The three pairs of large salivary glands—the sublingual, submandibular, and parotid glands—are responsible for secreting saliva in the mouth.

Question 4

How much saliva does an adult secrete every day?

Answer 4

An adult secretes one to two liters of saliva every day.

Question 5

What triggers salivation?

Answer 5

The thought or sight of food, especially if someone is hungry, can trigger salivation.

Question 6

How many pairs of large salivary glands are there in the mouth?

Answer 6

There are three pairs of large salivary glands in the mouth.

Question 7

What are the names of the three pairs of large salivary glands?

Answer 7

The three pairs of large salivary glands are the sublingual, submandibular, and parotid glands.

Question 8

What is the role of the small salivary glands in the mouth and pharynx?

Answer 8

The small salivary glands in the mouth and pharynx contribute to saliva production, although the three pairs of large salivary glands secrete the majority of saliva.

Question 9

How much saliva does an adult secrete every day?

Answer 9

An adult secretes one to two liters of saliva every day.

Question 10

Which gland is responsible for secreting the majority of saliva in the mouth?

Answer 10

The sublingual, submandibular, and parotid glands collectively secrete the majority of saliva in the mouth.

Question 11

What is the composition of saliva?

Answer 11

Saliva is 97% to 99.5% water.

Question 12

What enzyme does saliva contain?

Answer 12

Saliva contains the enzyme amylase.

Question 13

What is the role of amylase in saliva?

Answer 13

Amylase acts to break the bonds that link the components of carbohydrate molecules to each other.

Question 14

What is formed when food is moistened by saliva and chewed?

Answer 14

When food is moistened by saliva and chewed, it forms a soft ball called a bolus.

Question 15

How do the tongue and other mouth muscles contribute to the formation of a bolus?

Answer 15

The tongue and other mouth muscles shape and manipulate the moistened food into a bolus during chewing.

Question 16

What structures are involved in the safety of swallowing?

Answer 16

The safety of swallowing depends on three structures: the soft palate, the epiglottis, and the larynx.

Question 17

What does the soft palate do during swallowing?

Answer 17

The soft palate rises and closes off the nasal cavity during swallowing.

Question 18

What is the role of the epiglottis during swallowing?

Answer 18

The epiglottis lowers to cover the entrance to the larynx, preventing food from entering the airway.

Question 19

What happens to the larynx during swallowing?

Answer 19

The larynx rises during swallowing to help close off the entrance to the trachea.

Question 20

What path does food take after swallowing?

Answer 20

After swallowing, food travels through the pharynx and enters the esophagus, which leads to the stomach.

Question 21

Why is it important for the soft palate, epiglottis, and larynx to protect the trachea during swallowing?

Answer 21

Food caught in the trachea can block air from entering the lungs, potentially causing choking and death.

Question 22

What can happen if food enters the trachea instead of the esophagus during swallowing?

Answer 22

Choking can occur, which can be life-threatening if not addressed promptly.

Question 23

How can choking be prevented during swallowing?

Answer 23

The soft palate rises to close off the nasal cavity, the epiglottis lowers to cover the entrance to the larynx, and the larynx rises to close off the entrance to the trachea, ensuring that food enters the esophagus instead of the airway.

Question 24

How many stages does deglutition (swallowing) occur in?

Answer 24

Deglutition occurs in three stages.

Question 25

What happens during the voluntary oral stage of swallowing?

Answer 25

During the voluntary oral stage, you push the bolus toward the back part of your mouth with your tongue, and you have the option to spit out the food if desired.

Question 26

Describe the pharyngeal stage of swallowing.

Answer 26

In the pharyngeal stage, the soft palate rises to close off the nasal cavity, the epiglottis lowers to cover the entrance to the larynx, and the larynx rises to close off the entrance to the trachea, ensuring that food enters the esophagus instead of the airway.

Question 27

What characterizes the esophageal stage of swallowing?

Answer 27

The esophageal stage involves the movement of the bolus through the esophagus into the stomach through coordinated muscle contractions. This stage is involuntary and typically not under conscious control.

Question 28

What happens once the bolus reaches the pharyngeal stage of swallowing?

Answer 28

In the pharyngeal stage, the nasal cavity, larynx, and trachea become blocked by the soft palate, epiglottis, and larynx, ensuring that food enters the esophagus instead of the airway.

Question 29

How does the bolus move through the pharyngeal stage?

Answer 29

Several pharyngeal muscles contract to move the bolus along, facilitating its passage into the esophagus.

Question 30

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

Answer 30

The upper esophageal sphincter is a muscular structure that relaxes to allow the bolus to pass from the pharynx into the esophagus. Once the bolus has passed through, the sphincter closes back up.

Question 31

What occurs during the esophageal stage of swallowing?

Answer 31

During the esophageal stage, circular muscles of the esophagus contract and relax in a coordinated manner to move the bolus toward the stomach.

Question 32

What is peristalsis?

Answer 32

Peristalsis is the rhythmic contracting and relaxing of muscles that propels food or other contents through the digestive tract.

Question 33

What happens when the bolus reaches the bottom of the esophagus?

Answer 33

When the bolus reaches the bottom of the esophagus, the lower esophageal sphincter opens, allowing it to enter the stomach.