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The Gastrointestinal System and Aging
T.S. Dharmarajan, Amit Sohagia, and C.S. Pitchumoni
Questions and Answers
1. With regard to the Interstitial Cells of Cajal (ICC), which
of the following is most accurate?
A.The distribution of these cells is the same from infancy
to old age
B. These cells are present only in the small intestine
C.The cells regulate intestinal motility by generating slow
waves and determining the frequency of contractions
D. The cell number is regulated by dopamine
Answer: C.
The ICCs are the pacemaker cells of the intestine and
decline in number with each decade of life. They are mesenchymal cells located in the myenteric plexus, the muscularis propria and the submucosa through the entire
small intestine and colon. The cells are also present in the
stomach. The ICC declines in the stomach and colon with
age, influencing motility and response to insults from disease and drugs. However, their distribution is similar in
all age groups. ICC’s size is affected only in the myenteric plexus of the colon. There are no gender differences;
cell number is regulated by serotonin, rather than
dopamine.
2. Gastric acid facilitates the absorption of which of the following nutrients or supplements?
A. Vitamin B12
B. Calcium
C. Iron
D. All of the above
Answer: D.
Gastric acidity facilitates absorption of all three nutrients
stated above. Prolonged use of acid suppressive medication, atrophic gastritis, and gastric bypass surgery are risk
factors for B12, calcium, and iron deficiencies, but does
not appear to affect folate absorption. In the absence of
acid, calcium citrate may be a better choice for calcium,
and may be better absorbed than calcium carbonate.
Vitamin B12 requires gastric acid for the first step in splitting B12 from food protein. Although iron is better
absorbed in the presence of acid, it can be provided following meals if the patient develops adverse effects following iron administration on an empty stomach.
3. A 70-year-old man comes to your office with nocturnal
regurgitation of food for several months. Symptoms have
become worse recently, waking him up at night. He denies
dysphagia or odynophagia. His wife also noticed that his
voice has changed and feels he has an unpleasant breath
(halitosis). The patient attributes his symptoms to aging.
Which of the following is the most useful diagnostic study?
A. Upper endoscopy
B. Barium swallow
C. Esophageal manometry
D.Reassure him that his manifestations are due to
advanced aging and requires no evaluation
Answer: B.
The patient has Zenker’s diverticulum, a pulsion diverticulum that can present with dysphagia, regurgitation of
food material, halitosis, aspiration, hoarseness of voice,
and weight loss. A barium swallow is the most useful
diagnostic study for the condition. During upper endoscopy, it may be difficult to distinguish the lumen of the
diverticulum from the true lumen of the esophagus. There
is also the risk of perforation of diverticulum during
endoscopy.
4. A 75-year-old woman has lost weight; on further questioning
admits to a loss of appetite for most foods. Until 6 months ago
she enjoyed eating in her own home and the company of her
family. At this time she moved into an adult home. She is
fully capable of all her daily activities of daily living and is
cognitively intact. Her current weight is 130 lb as compared
to 152 about 6 months ago. Physical examination is noncontributory; her vital signs are normal. Colonoscopy for cancer
screening 5 years ago was negative. She has never smoked in
C.S. Pitchumoni and T.S. Dharmarajan (eds.), Geriatric Gastroenterology,
DOI 10.1007/978-1-4419-1623-5_5, © Springer Science+Business Media, LLC 2012
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T.S. Dharmarajan et al.
her life. Medications include calcium, vitamin D, and aspirin.
Routine blood tests are pending. The most likely cause is:
A. Age-related loss of appetite
B. Age-related gastroparesis loss of smell and appetite
C. Depression
D. Gastrointestinal cancer
Answer: C.
Age-associated taste disturbances or olfactory loss are
never profound with a weight loss of over 20 lb (over
10%) in 6 months. These physiological changes are gradual and subtle, and hardly affect quality of life. Olfaction
is most consistently lost with age, while taste discrimination rather than universal loss of appetite more likely to
be the manifestation. A weight loss of over 10% in 6
months requires evaluation. In this case a change in appetite in a patient who enjoys life following change of environment suggests an unhappy patient who is likely
depressed. While depression can be screened for, it is
unlikely to be proved by specific tests. A trial of antidepressants is called for. Testing for other causes of
weight loss such as gastric cancer, hyperthyroidism, or an
infectious disease is indicated only when initial routine
tests in conjunction with the exclusion of depression have
been addressed. In this nonsmoker, colonoscopy was negative, further supporting the plans stated.
5. True statements with regard to pancreatic polypeptide
include all of the following except:
A. Stimulates cholecystokinin (CCK) and secretin
B. Inhibits pancreatic exocrine secretion
C. Inhibits gallbladder contractility
D. Inhibition of intestinal motility
Answer: A.
The physiological effects of PP are not clear, but presumed to be inhibitory of pancreatic exocrine secretion.
Other roles are inhibitory effects on gallbladder contraction, intestinal motility, and hepatic glucose production. Hospitalized patients may have reduced appetite
through excessive release of PP. PP influences several
physiological functions including gall bladder contraction
and secretion, pancreatic exocrine secretion, intestinal
motility, and ileal contractions.
6. A true statement with regard to glucagon-like peptide
(GLP)-1 is:
A. Increase in type 2 diabetes mellitus
B. Opposes the incretin effect on oral glucose intake
C. Stimulates gastric acid secretion
D. Promotes incretin effect
Answer: D.
GLP-1 is produced by the L cells of the small intestine.
GLP levels are decreased in type 2 diabetes. The hormone
exerts its main effect by stimulating glucose-dependent
insulin release from the pancreas. The incretin effect
denotes a greater release of insulin compared to isoglycemic glucose infusion parenterally.
7. The gastric hormone, ghrelin is noted to:
A. Cause appetite suppression
B. Increase gastric acid
C. Levels are increased during fasting
D. Causes weight reduction
Answer: C.
Ghrelin is the natural ligand growth hormone secretogogue (GHS) receptor; it increases food intake and
weight gain. Circulating ghrelin level increases during
fasting and under conditions associated with negative
energy balance, such as starvation or anorexia. In contrast, levels are low following feeds and in obesity.
Ghrelin is a central neurohormonal regulator of food
intake and energy homeostasis and serves as a signal
for initiation of feeding. The usual premeal increase in
levels is not observed in gastric bypass patients and
may be one of the reasons for the effectiveness of gastric bypass surgery in inducing weight loss. Ghrelin
levels may decline with aging and partially explain
somatotropin regulation and anorexia in the older
adult.
8. Which one of the following statements is true regarding
the function of vagus nerve?
A. Mediates receptive relaxation of gastric antrum
B.Stimulates acid secretion by direct effect on muscarinic receptors on parietal, enterochromaffin cells
C. Inhibits gastrin and somatostatin release
D. Vagotomy enhances normal gastric emptying
Answer: B.
As food enters the proximal stomach, receptive relaxation
occurs through vagally mediated inhibition of fundic
tone. After the initial storage period of food in the proximal stomach (approximately 30 min), solids move on to
the antrum. Segmental contractions originate in the midbody of the greater curvature of the stomach. This process is also under the influence of the vagus. Further the
nerve is also responsible for stimulation of gastrin release
and inhibition of somatostatin. Vagal nerve dysfunction
(or injury or vagotomy) leads to failure of receptive relaxation, causing early satiety. In addition there is a failure of
antral grinding. The result is a delay in emptying of gastric contents. Patients who undergo vagotomy or damage
the nerve will have delay in gastric emptying.