chapter 41

When used appropriately, antibiotic treatment can effectively reduce bacteria populations and help fight infections. However, antibiotic treatments can have unintended effects. What is one concern when using antibiotics

Antibiotics may also kill the beneficial bacteria of the microbiome, thereby disrupting digestive health

_____ is secreted by the _____ and acts to emulsify _____ in the ____

Bile ... liver ... fats ... small intestine

Choose the correct statement from the list below: Carbohydrate absorption occurs primarily in the large intestine. Bile salts from the gall bladder are essential to the digestion of carbohydrates. Carbohydrates are fully digested after passage through the stomach . Carbohydrate digestion begins in the mouth with salivary amylase

Carbohydrate digestion begins in the mouth with salivary amylase

Which process is not required for an animal to obtain energy from food

Excretion

True or false? One advantage of having a tube-like digestive tract is that digestion of all compounds can take place simultaneously down the tract

False

Choose the correct statement from the list below: Fat digestion begins in the stomach with the activation of trypsinogen to trypsin. Free fatty acid absorption occurs in the small intestine. Bile salts from the pancreas are essential to the digestion of fats Fats are fully digested after passage through the mouth and stomach.

Free fatty acid absorption occurs in the small intestine

How do hydrogen ions (H+) and chloride ions (Cl-) get into the lumen of the stomach

H+ is actively transported from parietal cells into the lumen, while Cl- diffuses from parietal cells into the lumen

Pepsinogen is converted to its active form in the stomach by _______

HCl

What is one function of mucus in the lumen of the stomach

It protects the epithelium from being digested by gastric juice

Animals cannot produce enzymes to digest cellulose, yet many termite species consume cellulose from plant material as a main part of their diet. How do termites access the nutrients contained in cellulose

Mutualistic bacteria in the hindgut of the termite digest the cellulose into sugars

If you put the following events in the order they occur in the human digestive system, the third event in the series would be:

Pepsin activates pepsinogen

Which of the following is an example of positive feedback in the lumen of the stomach

Pepsin digests molecules of pepsinogen, producing more pepsin

Choose the correct statement from the list below: Mechanical digestion of proteins is more important than chemical digestion. Protein digestion begins in the small intestine with the activation of trypsinogen to trypsin The stomach has a high pH which allows for the activation of digestive enzymes. Proteins that are consumed in the diet are absorbed as individual amino acids following digestion

Proteins that are consumed in the diet are absorbed as individual amino acids following digestion

If you place a small piece of a cracker on your tongue, what would you expect to happen

Salivary amylase degrades the starch from the cracker into maltose

Which structure is not part of the alimentary canal

Salivary glands

What benefit is gained by intestinal bacteria living in a mutualistic relationship with an animal

The bacteria are provided with a regular source of nutrients

A researcher added a mixture of animal proteins to a physiological buffer solution (pH 7.4) in a test tube incubated at 37°C. The researcher then added purified pepsin to the mixture, but even after several hours, the proteins were not digested. Which of the following would explain this result

The pH was too high

Why do the cells of the digestive system secrete proteolytic enzymes, such as pepsin, in their inactive forms

These proteolytic enzymes, in active form, would digest the very tissues that synthesize them

What is the importance of the mucus that are released by salivary glands

They are glycoproteins that make food slippery enough to slide easily through the esophagus.

The epithelium that lines the stomach has many deep infoldings, or pits. In what way do these pits function as glands

They secrete gastric juice into the main chamber of the stomach

Stomach cells are moderately well adapted to the acidity and protein-digesting activities in the stomach by having ____

a thick, mucous secretion and active mitosis of epithelial cells

The large surface area in the gut directly facilitates _____

absorption

The process by which digested dietary substances cross cell membranes to be used by the body is known as ________

absorption

Fat digestion yields fatty acids and glycerol, whereas protein digestion yields amino acids. Both digestive processes _________

add a water molecule to break bonds

When digested, proteins are broken down into ____

amino acids

Which of these enzymes begins the breakdown of starch

amylase

birth defects of the neural tube in humans ____

are reduced from about 6% without folic acid supplements in the periconception interval to about 1% when the supplements were taken

To survive, all animals must _____

balance consumption of food with use and storage of nutrients

When digested, fats are broken down into ____

both glycerol and fatty acids

Animals obtain the energy they need for growth by

breaking down organic molecules

The "essential nutrients" for proper human nutrition include _____

calcium, sodium, potassium, and other minerals

Different types of food are eaten by various groups of animals, but it is usually true that _____

cellulose digestion in ruminant mammals occurs before the ingested foods reach the small intestine

The presence of fatty acids and amino acids in the chyme from the stomach triggers the small intestine to secrete a hormone known as _____

cholecystokinin, or CCK

The bile salts _____

emulsify fats in the duodenum

True or False? The liver is a component of the alimentary canal

false

After surgical removal of an infected gallbladder, a person must be especially careful to restrict dietary intake of

fat

After surgical removal of an infected gallbladder, a person must be especially careful to restrict dietary intake of _____

fat

Animals that migrate great distances would obtain the greatest energetic benefit of storing chemical energy as _____

fats

Your small intestine can absorb ____ without their being further digested

fructoses

The gastrovascular cavity differs from the alimentary canal in that only the gastrovascular cavity _____

has only a single opening

Cattle are able to survive on a diet consisting almost entirely of plant material because cattle _____

have cellulose-digesting, symbiotic microorganisms in chambers of their stomachs

Mechanical digestion, the process of breaking down large chunks of food into smaller pieces, is important because smaller pieces of food _______

have more surface area for chemical digestion than do larger pieces of food

Nutrient-rich blood from the intestine is carried through the ________ to the liver.

hepatic portal vein

What acid is responsible for stomach acidity

hydrochloric acid

list the four stages of food processing in the order in which they naturally occur

ingestion → digestion → absorption → elimination

Upon activation by stomach acidity, the secretions of the parietal cells ____

initiate the chemical digestion of protein in the stomach

In a healthy person, after a carbohydrate-rich meal, the production of ________ will increase, causing the uptake of ________ from the blood into liver cells

insulin; glucose

Which of the following organs is incorrectly paired with its function: stomach-protein digestion large intestine-bile production small intestine-nutrient absorption oral cavity-starch digestion pancreas-enzyme production

large intestine-bile production

Which of the following is hydrophobic and therefore insoluble in water

lipid

Bile is produced by the _____ and stored by the _____ until it is secreted into the small intestine

liver ... gall bladder

If you were to jog one kilometer a few hours after lunch, which stored fuel would you probably tap

liver glycogen and muscle glycogen

A fasting animal whose energy needs exceed those provided in its diet will draw on its stored resources in which order

liver glycogen, then muscle glycogen, then fat

Starch can be broken down into the disaccharide known as ____

maltose

The absorption of fats differs from that of carbohydrates in that _____

most absorbed fat first enters the lymphatic system, whereas carbohydrates directly enter the blood

For ingested foods, the first opportunity for enzymatic digestion occurs in the ____

mouth

If you were to jog 1 km a few hours after lunch, which stored fuel would you probably tap

muscle and liver glycogen

What is not a major activity of the stomach

nutrient absorption

Proteins consist of amino acids linked to

other amino acids

Part complete Secretin stimulates the _____ to secrete _____

pancreas ... bicarbonate

Cholecystokinin (CCK) stimulates the _____ to secrete _____

pancreas ... pancreatic enzymes

Over-the-counter medications for acid reflux or heartburn block the production of stomach acid. Which of the following cells are directly affected by this medication

parietal cells

The mammalian trachea and esophagus both connect to the

pharynx

Choose the correct anatomical sequence that presents the order in which food in the digestive system passes through

pharynx → esophagus → stomach → small intestine → large intestine

Starch is a type of _____

polysaccharide

The digestion of ________ begins in the stomach

protein

The lower esophageal sphincter surrounds the upper opening into the stomach. If this sphincter failed to properly constrict, there might be a problem with _____

regurgitation of acidic stomach contents into the esophagus, commonly called "heartburn"

The acidity of the stomach contents triggers the small intestine to secrete a hormone known as _____

secretin

Which of the following organs is correctly paired with its function: large intestine: bile production stomach: fat digestion pancreas: starch digestion small intestine: polysaccharide digestion

small intestine: polysaccharide digestion

Protein digestion begins in the ____

stomach

When the digestion and absorption of organic carbohydrates results in more energy-rich molecules than are immediately required by an animal, the excess is _____

stored as glycogen in the liver and muscles

Among mammals, it is generally true that _____.

the epiglottis prevents swallowed food from entering the trachea

The function of chylomicrons is to ________

transport lipids from the intestine to other organs

Part complete Among humans, increased interest in food intake normally occurs _____

via chemical signals released when the stomach is empty

What is the main component of gastric juice

water