The Digestion and Absorption of Food
565
6. Micelles increase the absorption of fat by
a. binding the lipase enzyme and holding it on the surface of
the lipid emulsion droplet.
b. keeping the insoluble products of fat digestion in small
aggregates.
c. promoting direct absorption across the intestinal epithelium.
d. metabolizing triglyceride to monoglyceride.
e. facilitating absorption into the lacteals.
7. Which of the following inhibits gastric HCl secretion during a
meal?
a. stimulation of the parasympathetic nerves to the enteric
nervous system
b. the sight and smell of food
c. distension of the duodenum
d. presence of peptides in the stomach
e. distension of the stomach
8. Which component of bile is not primarily secreted by
hepatocytes?
a. bicarbonate
b. bile salts
c. cholesterol
d. lecithin
e. bilirubin
9. Which of the following is true about segmentation in the small
intestine?
a. It is a type of peristalsis.
b. It moves chyme only from the duodenum to the ileum.
c. Its frequency is the same in each intestinal segment.
d. It is unaffected by cephalic phase stimuli.
e. It produces a slow migration of chyme to the large intestine.
10. Which of the following is the primary absorptive process in the
large intestine?
a. active transport of sodium from the lumen to the blood
b. absorption of water
c. active transport of potassium from the lumen to the blood
d. active absorption of bicarbonate into the blood
e. active secretion of chloride from the blood
Chapter 15 Quantitative and Thought Questions
(Answers appear in Appendix A.)
1. If the salivary glands were unable to secrete amylase, what effect
would this have on starch digestion?
2. Whole milk or a fatty snack consumed before the ingestion of
alcohol decreases the rate of intoxication. By what mechanism
may fat be acting to produce this effect?
3. A patient brought to a hospital after a period of prolonged
vomiting has an elevated heart rate, decreased blood pressure,
and below-normal blood potassium and acidity. Explain these
symptoms in terms of the consequences of excessive vomiting.
4. Can fat be digested and absorbed in the absence of bile salts?
Explain.
5. How might damage to the lower portion of the spinal cord
affect defecation?
6. One of the older but no longer used procedures in the
treatment of ulcers is abdominal vagotomy, surgical cutting
of the vagus (parasympathetic) nerves to the stomach. By
what mechanism might this procedure help ulcers to heal and
decrease the incidence of new ulcers?
Chapter 15 Answers to Physiological Inquiries
Table 15–4
The most common fi nding is an abnormally high
production of gastric (hydrochloric) acid due to gastrin
stimulation of the parietal cell of the stomach (see Figure
15–20). This high acidity can cause injury to the duodenum
because the pancreas cannot produce suffi
cient quantities of
bicarbonate to neutralize it (see Figure 15–27). The low pH
in the duodenum can also inactivate pancreatic enzymes (see
Figure 15–28) which can ultimately lead to diarrhea due to
unabsorbed nutrients, and to increased fat in the stool. The
spectrum of fi ndings in a patient with a gastrinoma is called
the Zollinger-Ellison syndrome.
Figure 15–14b
Aspiration of food during swallowing can lead
to occlusion (blockage) of the airways, which can result in a
disruption of oxygen delivery and carbon dioxide removal from
the pulmonary system. Aspiration of stomach contents can
lead to severe lung damage primarily due to the low pH of the
material (see description of acute respiratory distress syndrome
in Chapter 13).
Figure 15–18
Mucus secreted by the cells in the gastric pit
(see Figure 15–17) creates a protective coating and traps
bicarbonate. This gastric mucosal barrier protects the stomach
from the luminal acidity.
Figure 15–30
A portal vein carries blood from one capillary bed
to another capillary bed (rather than from capillaries to venules
as described in Chapter 12). The hypothalamo-pituitary portal
veins carry hypophysiotropic hormones from the capillaries
of the median eminence to the anterior pituitary gland where
they stimulate or inhibit the release of pituitary hormones
(Chapter 11).
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