Question 1

Each is true of wheat sensitivity,except one.Which is the exception?

Accepted Answer

Celiac disease and gluten sensitivity are two different conditions related to ingestion of gluten.Gluten is the structural protein component of the grains wheat,rye,barley,and triticale (a cross between wheat and rye).Whereas celiac disease is an autoimmune disorder,gluten sensitivity is neither allergic nor immunologic.Gluten-sensitive individuals are unable to tolerate gluten and can develop gastrointestinal symptoms,but the small intestine is not impaired (as is the case with celiac disease).A third category exists in which the patient develops an allergy to wheat.

Question 2

Each is true of microflora within the colon,except one.Which is the exception?

Accepted Answer

More than 1 trillion harmless bacteria thrive in the colon.Approximately 400 different species or microorganisms compose the microflora within the colon.Proliferation of pathogenic,or harmful,bacteria is inhibited by the protective features of the microflora.Types of food and medications ingested influence the type,activity,and relative numbers of bacteria.When intestinal flora is unbalanced,overall health can be affected.

Question 3

Each is true of protective elements within the microflora,except one.Which is the exception?

Accepted Answer

Prebiotics are nondigestible food ingredients that have beneficial effects on the host by selectively stimulating the growth or activity,or both,of beneficial colonic microorganisms.Stated succinctly,prebiotics are food for probiotics.Probiotics together with prebiotics that support their growth are called symbiotics because they work together to promote probiotic benefits more efficiently.Although probiotics can help to regulate bowel habits and relieve constipation,they are frequently used to treat diarrhea and to prevent irritable bowel syndrome.Constipation means having a bowel movement fewer than three times per week with hard,dry,difficult-to-pass stools.

Question 4

Masticatory efficiency refers to enhancement of gustatory effects.Even after a patient becomes fully adjusted to well-fitted dentures,masticatory efficiency is reduced compared with that of patients with their natural teeth.

Accepted Answer

The first statement is false; the second is true.Masticatory efficiency refers to how well a patient prepares food for swallowing.Gustatory sensations,more commonly known as the sense of smell,are intricately involved with appetite,but this is not definitive of masticatory efficiency.When masticatory efficiency declines,people frequently choose foods that require less chewing or they use techniques to soften foods,such as stewing meats,steaming vegetables,or dunking cookies in fluids.

Question 5

Alveolar bone is primarily composed of bony spikes forming a meshwork of spaces within cancellous bone.This spikelike formation is called interdental bone.

Accepted Answer

The first statement is true; the second is false.The spikelike formation of bone that forms a meshwork of spaces within cancellous bone is called trabecular bone.Cancellous bone is internal bone that appears spongy with little hollows that contain bone marrow.

Question 6

Missing teeth increase the potential for food obstruction in the airway because an inability to masticate food can result in larger chunks of food being swallowed.

Accepted Answer

Both the statement and the reason are correct and related.The act of chewing reduces food particle size.An inability to masticate food adequately can result in large chunks of food being swallowed,which increases the potential for food obstruction in the airway.Loss of even one permanent molar can decrease masticatory efficiency,which is defined as how well a patient prepares food for swallowing.

Question 7

A patient who reports stomach ulcers should avoid all the following foods,except one.Which is the exception?

Accepted Answer

Patients with ulcers of certain gastrointestinal tract disorders should avoid dietary constituents that increase hydrochloric acid and pepsin secretion.Foods to avoid include proteins,calcium,caffeine,coffee,and alcohol.Conversely,wheat (a whole grain),brown rice,and pastas are usually well tolerated because they do not typically stimulate gastric secretions.Note that although wheat is problematic in patients with gluten sensitivity,it is not contraindicated in patients with ulcers.

Question 8

Which is most likely to be absorbed within the stomach?

Accepted Answer

Most of the energy-providing nutrients are completely hydrolyzed and absorbed within the small intestine.The only nutrients completely absorbed within the stomach are water,alcohol,and a few water-soluble substances such as amino acids and glucose.Note that little absorption occurs in the stomach because few foods are completely hydrolyzed to nutrients that the body can use at this point.

Question 9

Each is true of swallowing and processing food,except one.Which is the exception?

Accepted Answer

The bolus is transported to the stomach by peristalsis,not osmosis,and gravity.Peristalsis is a series of contractile waves that mechanically move the bolus through the alimentary tract.Note that osmosis is the passage of water through a semipermeable membrane to equalize osmotic pressure.This process involves ionic control of movement of water (fluids)across membranes.

Question 10

The lower esophageal sphincter is a bony structure located within the stomach.It relaxes to permit food to move within the stomach on its way to the intestines.

Accepted Answer

The lower esophageal sphincter comprises a group of strong circular muscle fibers located just above the stomach.The lower esophageal sphincter relaxes to permit food into the stomach.

Question 11

Most nutrients are absorbed from the small to the large intestine,where the majority of digestion occurs.As the large intestine reabsorbs water and electrolytes,it forms the residue,also called feces.

Accepted Answer

The first statement is false; the second is true.Almost no absorption occurs in the large intestine; most absorption occurs in the small intestine.The large intestine forms and stores the residue,or feces,until defecation.Residue in the intestinal tract is defined as the total amount of fecal solids.

Question 12

Proteolytic enzymes are most likely to break down which food type?

Accepted Answer

Proteolytic enzymes target and break down proteins.Notice that the names of most enzymes begin with the type of food it targets and end in -ase.For example,lipase breaks down fats,also known as lipids.Other enzymes,such as pancreatic enzymes,contain the full name of the organ from which it originates.

Question 13

Nutrients are absorbed from the small intestine through the mucosa into the portal circulation.Nutrients are transported through the portal vein to the liver where metabolism is initiated.

Accepted Answer

Both statements are true.The portal circulation enables passage of nutrients from the gastrointestinal tract and spleen through the portal vein to the liver.Most nutrients are absorbed from the small intestine through the mucosa into the portal circulation.The portal circulation delivers the nutrients to the liver where metabolism is initiated.

Question 14

Passage of a permeable substance from a more concentrated solution to an area of lower concentration is called osmosis.Transport requiring a carrier and cellular energy is active transport.

Accepted Answer

The first statement is false; the second is true.Osmosis,active transport,and passive diffusion are three mechanisms that aid in transporting materials during absorption of nutrients.Passage of a permeable substance from a more to a less concentrated solution is called passive diffusion.Osmosis is the passage of water through a semipermeable membrane to equalize osmotic pressure exerted by ions in solutions.Active transport is accurately described in the question.

Question 15

An adult stomach functions as a reservoir to hold an average meal for 6 to 8 hours.The rate of passage through the stomach (fastest to slowest)is liquids,proteins,carbohydrates,and fats.

Accepted Answer

The first statement is false; the second is true.An adult stomach functions as a reservoir to hold an average meal for 3 to 4 hours.The stomach empties at different rates depending on its size and the composition of the chyme.The rate of passage,fastest to slowest,is liquids,carbohydrates,proteins,and fats.Note that fats remain in the stomach longer,increasing satiety for a longer time than proteins or carbohydrates.

Question 16

In a well-functioning alimentary tract,stomach contents do not "back wash" into the esophagus because the pyloric sphincter prevents foodstuff from seeping back into the esophagus.

Accepted Answer

The first statement is true; the second is false.When all components are functioning correctly,the lower esophageal,not pyloric,sphincter prevents backwash of foodstuff (chyme).The pyloric sphincter performs a similar task in a different location.It releases small amounts of chyme from the stomach into the small intestine for digestion and absorption.

Question 17

Each accurately describes aspects of the villi,except one.Which is the exception?

Accepted Answer

Villi increase,rather than decrease,the surface area of the alimentary tract to approximately 3000 square feet.Note that microvilli are minute cylindrical processes located on the surface of intestinal cells,greatly increasing their absorptive surface area.

Question 18

Most absorption occurs in the stomach because the gastric juices secreted by the stomach effectively hydrolyze and prepare nutrients for absorption.

Accepted Answer

Neither the statement nor the reason is correct.Very little absorption occurs in the stomach because few foods are completely hydrolyzed to nutrients that the body can use at this stage.Nutrients that can be absorbed from the stomach include some water,alcohol,and a few water-soluble substances such as amino acids and glucose.Most of the energy-providing nutrients are completely hydrolyzed and absorbed within the small intestine.

Question 19

Intestinal digestion of fats and insoluble molecules is enhanced because emulsification by bile salts facilitates breakdown of such substances into smaller particles.

Accepted Answer

Both the statement and the reason are correct and related.This question accurately describes emulsification,or breakdown of fats and soluble substances within the intestine.Importantly,emulsification allows greater exposure of fats to intestinal and pancreatic lipases.Peristalsis facilitates mixing and emulsification processes.

Question 20

Pancreatic enzymes enter the colon through the pancreatic duct.Produced and stored in the pancreas,these enzymes hydrolyze carbohydrates,proteins,and fats.

Accepted Answer

The first statement is false; the second is true.Pancreatic enzymes enter the duodenum,not the colon,through the pancreatic duct.The duodenum is the first section of the small intestine.

Quiz 3: The Alimentary Canal: Digestion and Absorption