Chapter 40: Structure and Function of the Digestive System

Chapter 40: Structure and Function of the Digestive System

 

Complete Chapter Questions With Answers

 

Sample Questions Are Posted Below

 

MULTIPLE CHOICE

 

1. In the mouth and stomach, salivary a-amylase initiates the digestion of which nutrients?

a.	Proteins	c.	Fats
b.	Carbohydrates	d.	Fiber

 

 

ANS:  B

Salivary a-amylase is an enzyme that initiates only carbohydrate digestion in the mouth and stomach.

 

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2. Which elements in saliva protect against tooth decay?

a.	Salivary a-amylase and ptyalin
b.	Secretin and IgA
c.	Endogenous enamelin and salivary b-amylase
d.	Exogenous fluoride and a pH of 7.4

 

 

ANS:  D

The bicarbonate concentration of saliva sustains a pH of approximately 7.4, which neutralizes bacterial acids and prevents tooth decay. Exogenous fluoride (e.g., fluoride in drinking water) is absorbed and then secreted in the saliva, providing additional protection against tooth decay. Decay prevention is not associated with any of the other options.

 

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3. Saliva contains which immunoglobulin (Ig)?

a.	IgA	c.	IgG
b.	IgE	d.	IgM

 

 

ANS:  A

Saliva contains only IgA, which helps prevent infection.

 

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4. What effect is a result of inhibiting the parasympathetic nervous system with a drug such as atropine?

a.	Salivation becomes thinner.	c.	The pH of saliva changes.
b.	Salivation decreases.	d.	Digestive enzymes are inhibited.

 

 

ANS:  B

The sympathetic and parasympathetic divisions of the autonomic nervous system control salivation. Because cholinergic parasympathetic fibers stimulate the salivary glands, atropine (an anticholinergic agent) inhibits salivation and makes the mouth dry. None of the other options is a result of drugs such as atropine.

 

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5. Food enters the stomach via which sphincter?

a.	Cardiac	c.	Gastric
b.	Upper esophageal	d.	Fundal

 

 

ANS:  A

Each end of the esophagus is opened and closed by a sphincter. The upper esophageal sphincter (cricopharyngeal muscle) prevents entry of air into the esophagus during respiration. The lower esophageal sphincter (cardiac sphincter) prevents regurgitation from the stomach. The lower esophageal sphincter is located near the esophageal hiatus—the opening in the diaphragm where the esophagus ends at the stomach. The cardiac sphincter is the only option that fulfills the function described in the question.

 

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