course assessment on Structure and
Function of the Digestive System
ANS: B
Salivary -amylase is an enzyme that initiates only carbohydrate digestion in the mouth and
stomach. - answer ✔✔-In the mouth and stomach, salivary -amylase initiates the digestion of
which nutrients?
a. Proteins
b. Carbohydrates
c. Fats
d. Fiber
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. - answer ✔✔-Which elements in saliva protect against tooth decay?
a. Salivary -amylase and ptyalin
b. Secretin and IgA
c. Endogenous enamelin and salivary -amylase
d. Exogenous fluoride and a pH of 7.4
, ANS: A
Saliva contains only IgA, which helps prevent infection. - answer ✔✔-Saliva contains which
immunoglobulin (Ig)?
a. IgA
b. IgE
c. IgG
d. IgM
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. - answer ✔✔-What
effect is a result of inhibiting the parasympathetic nervous system with a drug such as
atropine?
a. Salivation becomes thinner.
b. Salivation decreases.
c. The pH of saliva changes.
d. Digestive enzymes are inhibited.
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. - answer ✔✔-5. Food
enters the stomach via which sphincter?