Mahan & Escott-Stump: Evolve Resources for Krause's Food & Nutrition Therapy, 12th Edition

Test Bank

Chapter 1: Digestion, Absorption, Transport, and Excretion of Nutrients 

MULTIPLE CHOICE

	1.	Digestion of which of the following nutrients begins in the mouth?
a.	Vitamins	
b.	Proteins	
c.	Carbohydrates	
d.	Minerals	

ANS:	C
Amylase in the saliva begins a minimal digestion of starch in the mouth. Although oropharyngeal secretions also contain lipase, because fat is still mixed within whole foods and spends little time in the mouth and esophagus, fat digestion does not really begin. Vitamins undergo absorption as they generally do not have to be broken down from larger molecules.

REF:	p. 9

	2.	Pepsinogen is converted to pepsin when it comes in contact with
a.	enterokinase.	
b.	trypsinogen.	
c.	hydrochloric acid.	
d.	peptidases.	

ANS:	C
Pepsinogen is secreted in the stomach and converted to its active form by the acid environment of the stomach. Enterokinase is secreted by the brush border of the small intestine in response to presence of chyme. Trypsinogen is secreted by the pancreas and activated by enterokinase. Various peptidases are secreted by either brush border or the pancreas.

REF:	p. 10

	3.	What is the function of enterogastrone?
a.	Inhibits carbohydrate digestion	
b.	Enhances carbohydrate digestion	
c.	Enhances protein digestion	
d.	Inhibits gastric secretion and motility	

ANS:	D
Enterogastrone is the hormone secreted by duodenal mucosa cells when fat is present in the duodenum, thus slowing the delivery of fat from the stomach and allowing time for fat digestion and micelle formation. Carbohydrate digestion is enhanced or inhibited based on the form of the carbohydrate (e.g., monosaccharide vs. fiber). Glucagon-like peptide 1 is a hormone secreted in response to glucose intake, and it will delay stomach emptying and promote satiety. Gastrin and cholecystokinin are hormones that promote protein digestion through the stimulation of secretion of pepsinogen and pancreatic proteolytic enzymes, respectively.

REF:	pp. 18-19

	4.	Which of the following is formed by bacterial synthesis in the colon?
a.	Vitamin K	
b.	Vitamin D	
c.	Vitamin B6	
d.	Niacin	

ANS:	A
Colonic bacteria produce vitamin K, vitamin B12, thiamin, and riboflavin. Vitamin D may be metabolized by exposure of precursor vitamin D in the skin to ultraviolet light. The human body can synthesize niacin from the amino acid tryptophan. Vitamin B6 must be obtained from dietary sources such as meats, whole grains, vegetables, and nuts.

REF:	p. 14

	5.	Following surgical removal of a large portion of the small intestine, what functional complication is most likely to develop?
a.	Changes in dietary habits	
b.	Impaired digestion	
c.	Loss of absorptive tissue	
d.	Elimination of dietary residue	

ANS:	C
The small intestine is the primary site of nutrient absorption due to its large absorption surface area. Secretions from the liver, gallbladder, and pancreas can still contribute to digestion of intestinal contents. However, decreased absorption of nutrients and food components may result in more intestinal remains and residue. A patient may change dietary habits as a result of gastrointestinal discomfort experienced after intestinal resection, but this is not a functional complication.

REF:	p. 11

	6.	The sight or smell of food produces vagal stimulation of the parietal cells of the gastric mucosa, resulting in the increased production of what?
a.	Insulin	
b.	Hydrochloric acid	
c.	Cholecystokinin	
d.	Secretin	

ANS:	B
Parasympathetic innervation helps prepare the stomach for the potential of receiving food. After food has entered the stomach and chyme is passed on to the small intestine, then secretin and cholecystokinin will be secreted to pancreatic and gallbladder secretions and reductions in stomach emptying and duodenal motility. Secretin, glucose-dependent insulinotropic polypeptide, and glucagon-like peptide 1 will then all contribute to stimulation of insulin secretion.

REF:	p. 7

	7.	If a patient experiences malabsorption of fat resulting from an impaired ability to produce adequate bile salts for micelle formation, how may fat absorption be improved?
a.	By increasing short-chain fatty acids in the diet	
b.	By increasing medium-chain fatty acids in the diet	
c.	By increasing long-chain fatty acids in the diet	
d.	By restricting dietary intake of cholesterol	

ANS:	B
Medium-chain fatty acids of 8 to 12 carbons can be absorbed directly by mucosal cells without the presence of bile. The long-chain fatty acids require micelle formation for absorption. Short-chain fatty acids result from bacterial fermentation of malabsorbed carbohydrates and fibers. As bile is produced from cholesterol, dietary restriction of cholesterol is negligible in regard to improvements in fat absorption.

REF:	p. 18

	8.	What is the function of secretin?
a.	Stimulation of gastric secretions and increased motility	
b.	Stimulation of gallbladder contraction and the release of bile	
c.	Stimulation of the pancreas to secrete water and bicarbonate	
d.	Stimulation of the parietal cells to secrete gastrin	

ANS:	C
Secretin is the hormone that works in opposition to gastrin. Whereas gastrin stimulates stomach digestion activities, secretin decreases gastric output and promotes pancreatic secretions to neutralize the acidity of chyme. Cholecystokinin is also secreted when chyme enters the duodenum, and it is responsible for stimulating the gallbladder.

REF:	p. 8

	9.	What is the intestinal hormone released in the presence of fat and glucose that results in release of insulin?
a.	Glucose-dependent insulinotropic peptide (GIP)	
b.	Cholecystokinin (CCK)	
c.	Gastrin	
d.	Pancreatic lipase	

ANS:	A
GIP is released when glucose and fat are present in the small intestine. CCK secretion results in pancreatic enzymes, such as lipase, and bicarbonate secretion and gallbladder secretion. Gastrin stimulates stomach digestion activities.

REF:	p. 9

	10.	Which of the following is a list of enzymes released from the pancreas?
a.	Insulin, trypsin, secretin	
b.	Lactase, isomaltase, dextrinase	
c.	Protease, pepsin, gastrin	
d.	Trypsin, chymotrypsin, carboxypeptidase	

ANS:	D
Trypsin, chymotrypsin, and carboxypeptidase are three protein digestive enzymes secreted by the pancreas. Insulin is an endogenous hormone secreted by the pancreas. Secretin is a hormone secreted by the small intestine. Lactase and isomaltase (also known as á-dextrinase) are brush border enzymes. Pepsin, which is a protease, and gastrin are hormones secreted by the stomach.

REF:	p. 6

	11.	In what form is dietary fat absorbed from the lumen of the intestine?
a.	Chylomicron	
b.	Micelle	
c.	Triglyceride	
d.	Lipoprotein	

ANS:	B
Fats must be emulsified into micelles so that they may cross the unstirred water layer that borders the brush border membranes. These micelles will leave monoglycerides and fatty acids at the brush border where they are reabsorbed and reassembled as triglycerides. The triglycerides are packaged with cholesterol, fat-soluble vitamins, and phospholipids into chylomicrons, which pass into the lymphatic circulation. When these reach the liver, the chylomicron components will be repackaged into low-density lipoproteins.

REF:	pp. 12-13

	12.	Which of the following is an advantage to using medium-chain triglycerides when fat malabsorption occurs?
a.	MCTs pass directly into the portal vein without esterification.	
b.	MCTs pass directly into the lymphatic system without esterification.	
c.	MCTs transport long-chain triglycerides through the lymph.	
d.	MCTs pass through the lymphatic system undigested.	

ANS:	A
In abetalipoproteinemia, chylomicron synthesis is impaired, which results in impaired transport of fatty acids into the lymphatic circulation. Long-chain fatty acids need to be reesterified into triglycerides for packaging into chylomicrons. The benefit of use of MCTs is that they can bypass lymphatic circulation and be directly transported to the liver.

REF:	p. 18

	13.	By which transport mechanism are most vitamins absorbed from the small intestine into the blood?
a.	Passive diffusion	
b.	Active diffusion	
c.	Facilitative diffusion	
d.	Passive osmosis	

ANS:	A
Passive diffusion is limited by the number of channels available for nutrients to randomly pass through. Facilitated diffusion requires the presence of carrier proteins, which may be limited by the health and nutritional status of the person. Active transport requires energy, which also may be limited by the person’s health and nutritional status. Osmosis occurs in regard to concentration gradient and only involves the movement of water, not vitamins.

REF:	p. 18

	14.	What is primarily absorbed by the large intestine?
a.	Water and fats	
b.	Carbohydrates	
c.	Proteins	
d.	Water and electrolytes	

ANS:	D
Water and electrolytes are usually the only absorbable remnants of dietary intake that reach the large intestine. Fats, carbohydrates, and proteins from the diet are absorbed throughout the small intestine.

REF:	p. 13

	15.	What happens to cellulose and lignin as they go through the GI tract?
a.	They are converted into glucose prior to absorption.	
b.	They are converted into glucose and absorbed by active transport.	
c.	They are excreted in the feces unchanged.	
d.	They are excreted in the feces as glucose.	

ANS:	C
In humans, the secreted amylases cannot split the β1-2 and β1-4 linkages between the saccharides within the cellulose molecule. As a result, no individual glucose molecules are broken off.

REF:	p. 16

	16.	Which is the process by which minerals are absorbed when they are bound to an acid, organic acid, or amino acid?
a.	Cotransportation	
b.	Carrier protein	
c.	Competitive inhibition	
d.	Chelation	

ANS:	D
Chelation refers to the binding of a cation mineral to a ligand, and not a whole protein. Cotransporters carry two different minerals at a time, such as the case with sodium and phosphorus. An overlap of mineral transport mechanisms may lead to competitive absorption between minerals in the presence of other minerals, such as the case with iron or zinc supplementation leading to a decrease in copper absorption.

REF:	p. 18

	17.	How often do the cells lining the intestinal tract recycle?
a.	Every 2 to 3 days	
b.	Every 3 to 5 days	
c.	Every 5 to 7 days	
d.	Every 10 to 14 days	

ANS:	B
Intestinal mucosal cells have a life span of 3 to 5 days before they are sloughed off and recycled. They are fully functional only for the last 2 to 3 days as they migrate to the distal third of the villi.

REF:	p. 3

	18.	Which of the following bacterial genuses tend to occur the most frequently in the adult colon?
a.	Bacteroides	
b.	Escherichia	
c.	Lactobacilli	
d.	Helicobacter	

ANS:	A
Bacteroides are the primary anaerobic colonic flora in adults. Escherichia coli are predominant in the distal ileus. Lactobacilli are the primary flora in the infant’s gastrointestinal tract until the introduction of solid foods. Helicobacter pylori are acid-resistant bacteria that contribute to gastritis and ulcer development.

REF:	p. 14

	19.	What effect may be achieved by eating a diet high in prebiotic carbohydrates?
a.	Decreased SCFA production in the bowel	
b.	Increased growth of Lactobacilli species	
c.	Decreased absorption of bile salts	
d.	Increased absorption of cation minerals	

ANS:	C
The use of prebiotic carbohydrates favors the growth of friendly bacteria such as lactobacilli and bifidobacteria. These bacteria will ferment the prebiotic carbohydrates, promoting increased short-chain fatty acid production. These types of carbohydrates have not been demonstrated to have a bile-sequestering effect. Impairments in absorption of cation minerals tend to be in relation to phytates and oxalates that are present in plant foods.

REF:	p. 15

	20.	How long does it take for small intestine contents to reach the ileocecal valve?
a.	18 to 72 hours	
b.	3 to 8 hours	
c.	1 to 2 hours	
d.	2 to 3 hours	

ANS:	B
Travel of contents through the small intestine takes 3 to 8 hours. A liquid meal will empty the stomach within 1 to 2 hours of eating. A solid meal takes 2 to 3 hours. Total transport, from mouth to anus, takes 18 to 72 hours on average.

REF:	p. 11