chapter 23 digestive system

How many total permanent teeth should an adult have, assuming none have been lost or removed?

32 There are two incisors (2I), one canine (1C), two premolars (2PM) and three molars (3M) for a total of 8 on each side of each jaw. Multiply by 4 for a total of 32 adult teeth.

Select the description below that illustrates a difference between a sphincter and circular muscle.

A sphincter is a thickening of circular muscle that can prevent the movement of digesting materials while circular muscle is involved in propulsion digesting material.

Which vitamin requires intrinsic factor in order to be absorbed?

B12

Choose the incorrect statement regarding bile.

Bile contains enzymes for digestion.

Which of the following is NOT a function of saliva?

Saliva contains enzymes that begin the chemical breakdown of proteins. Saliva contains components with functions ranging from starch breakdown to fighting bacterial infection, but it does not contain any enzymes that digest protein.

Salivary amylase is a digestive enzyme not featured in the Concept Map. Which of the following describes its function? breaks down complex starches into smaller units, and where in the body does this occur?

Salivary amylase breaks down complex starches into smaller units in the mouth. Salivary amylase in saliva breaks down starch into oligosaccharides.

Which of the following best describes the capillary wall structure found in the liver lobules?

The capillary walls have openings that allow large proteins and small cells to pass through. The capillary walls in the lobules of the liver are sinusoidal and allow large proteins and even blood cells to pass, permitting the liver to perform its functions.

Which of the following does NOT correctly describe basic regulation of digestive activity?

The enteric nervous system is under conscious control. Neural control over the digestive system is through the autonomic nervous system, which does not function under conscious control mechanisms.

All of the following are true of swallowing (deglutition) except one. Select the statement that is NOT true of swallowing.

The epiglottis assists in propelling food into the trachea.

Peristaltic waves are ________.

Waves of muscular contractions that propel the contents of a tubular organ along its tract

Chemical or mechanical process of breaking down foodstuffs into simpler units.

digestion

When we ingest large molecules such as lipids, carbohydrates, and proteins, they must undergo catabolic reactions whereby enzymes split these molecules. This series of reactions is called ________.

digestion

The __________ is the first segment of the small intestine.

duodenum

The mechanical and chemical receptors that control digestive activity are located ________.

in the walls of the tract organs

Which teeth in the permanent dentition are best suited for cutting or nipping off pieces of food?

incisors The location and shape of the incisors make them ideally suited for cutting and nipping food.

A ruptured appendix is life threatening because ________.

it is likely to cause massive infection of the abdominopelvic cavity

The ________ contains lobules with sinusoids (lined with macrophages) that lead to a central venous structure.

liver

In the enteric nervous system, a long reflexive pathway has an advantage over a short reflexive pathway in the fact that ________.

long reflexive pathways can be stimulated by things outside of the GI tract

The lamina propria is composed of ________.

loose connective tissue

How would you classify chewing food?

mechanical breakdown Chewing breaks apart and grinds food and mixes it with saliva.

The sheets of peritoneal membrane that hold the digestive tract in place are called ________.

mesentaries

What muscle forms the labia of the mouth and controls most lip movement, including puckering?

orbicularis oris The orbicularis oris muscle is positioned surrounding the mouth and within the labia. It acts to control the movement of the lips.

This group of enzymes digests the majority of ingested fat.

pancreatic lipases Pancreatic lipases break the bonds between fatty acid chains and glycerol after the fats have been emulsified.

Which of the following produce intrinsic factor?

parietal cells

Where does the process of segmentation occur?

small intestine Several areas of the digestive tract are capable of peristalsis, which propels food onward, but only the small intestine undergoes segmentation. The purpose is to mix food with enzymes and bring it close to intestinal walls.

Absorption of nutrients primarily occurs in the __________.

small intestine Most nutrients are absorbed in the small intestine before the chime reaches the ileum.

Stellate macrophages are found in the liver and are responsible for removing bacteria and worn-out cells.

true

The major means of propulsion through the alimentary canal is peristalsis.

true

Which of the following is not an important contribution of the bacterial microbiota found in the large intestine?

Digestion of proteins Digestion of proteins is performed in the stomach and small intestine using enzymes produced by the body, not by gut bacteria.

Which of these enzymes is NOT produced in the pancreas?

Enteropeptidase Enteropeptidase is a protein produced by and bound to the membranes of intestinal cells.

Which of the following constitute a portal triad?

a bile duct along with a portal venule and arteriole A bile duct along with a portal venule and arteriole constitute a portal triad. The blood vessels provide blood flow to the lobule and the bile duct drains bile.

Which of these best describes a lacteal?

a lymphatic vessel designed to help introduce fats to the blood Lacteals are lymphatic vessels located in the intestinal villi. Their ability to accept large materials makes them helpful in transporting large fat particles (called chylomicrons) into the lymph for eventual transport to the bloodstream.

Which of the following would likely be absorbed in the stomach?

a serving of alcohol

Process by which simpler chemical units pass through the lumen of the gastrointestinal tract into the blood or lymph

absorption

Which major process involves the removal of water from intestinal contents?

absorption Absorption is the passage of digested end products and water from the lumen of the gastrointestinal tract through the mucosal cells into blood or lymph.

What structural modification of the small intestine slows the movement of chyme through the lumen?

circular folds The circular folds of the small intestine help slow the progress of food through the intestine so that it can be digested and absorbed more effectively. These folds also increase surface area and help mix chyme.

Most gastric ulcers are due to excessive production of hydrochloric acid.

false

Peyer's patches are primarily found in the submucosa of the duodenum.

false

The only essential function of the stomach is to begin the digestion of proteins.

false

The soft palate reflexively opens the nasopharynx to allow the passage of food, which is now called a bolus.

false

When swallowing, the glottis covers the epiglottis.

false

Bacteria that reside in the large intestine make vitamin C.

false Bacteria that reside in the large intestine make B complex vitamins and vitamin K. Enteric bacteria also form gases such as CO2, methane, H2, and N2 as byproducts of metabolizing nondigested starches such as cellulose.

Chief cells secrete inactive pepsinogen in order to prevent acid erosion inside of the chief cells.

false Chief cells do secrete pepsinogen, but the result is unrelated to acidity. When pepsinogen is activated by HCl secreted by the parietal cells, it is converted into pepsin, an active enzyme that digests proteins. Pepsinogen is produced and secreted in the inactive form to avoid self-digestion of the very cells/glands that produce this protein-digesting enzyme.

Peritoneal organs are completely covered in a serous membrane and have a dorsal and ventral mesentery.

false Peritoneal organs are covered in a serous membrane, the peritoneum. However, many peritoneal organs only have a dorsal mesentery. A ventral mesentery is only evident on a few peritoneal organs.

Which of the following are types of papillae on the tongue that contain taste buds?

fungiform and vallate

Which cells in the small intestine's mucosa secrete mucus?

goblet cells Goblet cells, which secrete mucus and are found in several areas of the digestive tract, are located on the villi of the small intestine.

The __________ circulation collects nutrient-rich venous blood draining from the digestive viscera.

hepatic portal The hepatic portal circulation drains all of the blood from the digestive organs and routes that blood through the liver for processing.

Which vessel delivers nutrient-rich blood to the liver from the digestive tract?

hepatic portal vein All blood from the digestive organs as well as the spleen is delivered to the liver in the hepatic portal vein before being returned to the general circulation.

The ducts that deliver bile and pancreatic juice from the liver and pancreas, respectively, unite to form the ________.

hepatopancreatic ampulla

Enzymatic breakdown of any type of food molecule.

hydrolysis

This type of chemical reaction typically occurs as nutrients are digested in the body.

hydrolysis Hydrolysis refers to the enzymatic breakdown of large polymers into monomers while adding the parts of a water molecule to the broken bonds.

Which of the following is the major process or function that occurs in the stomach?

mechanical breakdown Mechanical breakdown occurs in the stomach by churning.

Which layer of the stomach contains the gastric pits that secrete mucus, acid, and digestive enzymes?

mucosa The mucosa of the stomach contains the epithelial lining and the gastric pits, which extend down into the mucosa but do not penetrate the submucosa.

An individual diagnosed with celiac disease would be prescribed a gluten-free diet in order to __________.

prevent inflammation caused by malabsorption of gluten protein In a person with celiac disease, gluten breakdown products interact with the immune system in the digestive tract, leading to damage of the intestinal lining.

Hepatocytes do NOT ________.

produce digestive enzymes

The function of goblet cells is to ________.

produce mucus that protects parts of the digestive organs from the effects of powerful enzymes needed for food digestion

Which of the following functions is NOT correctly matched with its description? propulsion: physical breakdown of ingested food in the GI tract mechanical breakdown: churning movements in the GI tract ingestion: taking food into the digestive tract absorption: transport of chemically digested nutrients into the blood or lymph

propulsion: physical breakdown of ingested food in the GI tract Propulsion is the movement of ingested food through the GI tract.

Which of the following digestive processes could be affected by a patient's taking a large amount of antacids?

protein digestion Protein digestion is partially accomplished by pepsin, an enzyme that works best in a pH range of 1.5 to 2.5.

Which area of the stomach directly adjoins the small intestine?

pylorus The pylorus is the lowest part of the stomach. It attaches to and empties food into the small intestine via the pyloric sphincter.

Which of the following is NOT a factor that helps create the stomach mucosal barrier?

secretion of pepsinogen

Which digestive process does NOT occur in the mouth? mechanical breakdown ingestion segmentation digestion

segmentation Segmentation is the back-and-forth mixing movement of food in the small intestine. The process of chewing and mixing food with saliva in the mouth is known as mastication.

From the esophagus to the anus, the walls of the alimentary canal have the same four basic tunics. The __________ is the outermost layer of the walls of the intraperitoneal organs.

serosa The visceral peritoneum, or serosa, forms the outermost layer (tunic) along most of the alimentary canal. In the esophagus, which is located in the thoracic instead of the abdominopelvic cavity, the serosa is replaced by an adventitia (dense connective tissue). Retroperitoneal organs have both an adventitia (on the side facing the dorsal body wall) and a serosa (on the side facing the peritoneal cavity).

Which organ of the digestive tract is the body's major digestive organ?

small intestine The small intestine is the major digestive organ because it is the site of the majority of enzymatic digestion and absorption of nutrients.

All the chemical and mechanical phases of digestion from the mouth through the small intestine are directed toward changing food into forms that can pass through the epithelial cells lining the mucosa into the underlying blood and lymphatic vessels.

true

The major role of absorption in the ileum is to reclaim bile salts to be recycled back to the liver.

true

The pancreas has both an endocrine and an exocrine function.

true

The peritoneum is the most extensive serous membrane in the body.

true

Which of the following is the best explanation of the benefit in the digestive system having the largest collection of lymphoid tissue (MALT) at the distal end of the small intestine?

The huge numbers of bacteria living in the large intestine must be prevented from entering the lumen of the small intestine so they do not absorb the nutrients before the host can.

Which of the following is NOT a characteristic of the stomach?

The stomach releases enzymes that digest carbohydrates. The chief cells of the stomach secrete enzymes that chemically digest lipids and proteins, but not carbohydrates.

All but one of the following is a function of the low pH found in the stomach. Select the description below that does NOT reflect a role of stomach acid.

The stomach's acid catabolically breaks down food stuffs in preparation for absorption.

The enterohepatic circulation reabsorbs bile salts in the distal portion of the small intestine (ileum). All of the following statements about the enterohepatic circulation are true except one. Select the statement below that is NOT true of the enterohepatic circulation?

All of the components of bile are recycled by this circulation.

Which of the following is NOT characteristic of the large intestine?

It is longer than the small intestine.

Which of these structures is found in the stomach but nowhere else in the alimentary canal?

an oblique muscle layer All areas of the alimentary canal have a circular and a longitudinal layer of muscle. The stomach has an additional oblique layer of muscle for "wringing" itself while processing food.

Which of the following inhibits salivation? the sight or smell of food being stressed or frightened ingestion of spicy foods relaxing after a meal

being stressed or frightened The sympathetic division of the autonomic nervous system is associated with fight-or-flight responses. Stimulation of the salivary glands by the SNS tends to inhibit flow, as when you are scared or nervous and your mouth "goes dry."

Which of the following is not a secretion of the pancreas?

bile Bile is secreted by the liver.

How are vitamins A, D, E, and K absorbed by the body?

by being incorporated into micelles Fat-soluble vitamins are incorporated into micelles when fats are present. Without dietary fats available, these vitamins are not absorbed.

Chemical digestion reduces large complex molecules to simpler compounds by the process of ________.

catabolism

Pepsinogen, an inactive digestive enzyme, is secreted by the ________.

chief cells of the stomach

Chyme entering the large intestine normally consists of __________.

indigestible fiber, enteric bacteria, and water The small intestine absorbs virtually all nutrients from chyme before it reaches the large intestine, leaving only indigestible wastes, water, and millions of bacteria.

Which of these is NOT part of the splanchnic circulation? hepatic portal vein inferior vena cava celiac artery superior mesenteric artery

inferior vena cava

Which of the following is produced in the stomach and contributes directly to the absorption of vitamin B12?

intrinsic factor Without the production of intrinsic factor by gastric parietal cells, the body would not be able to absorb vitamin B12 in the small intestine.

Most absorption of nutrients occurs in the __________.

jejunum and ileum The majority of nutrients are absorbed as digesting foods make their way through the jejunum (~8 feet long) and ileum (~12 feet long) of the small intestine. Although absorption begins in the duodenum, it is too short (~12 inches long) to account for the majority of nutrient absorption.

The capillaries that nourish the epithelium and absorb digested nutrients lie in the ________.

lamina propria

Which layer of the alimentary canal is constructed from either stratified squamous or simple columnar epithelium?

mucosa The mucosa's inner lining is composed of columnar epithelium for most of the alimentary canal. Stratified squamous is used in the esophagus, oral cavity, and anus.

From the esophagus to the anal canal, the walls of every organ of the alimentary canal are made up of the same four basic layers. Arrange them in order from the lumen.

mucosa, submucosa, muscularis externa, and serosa

Gastric pits, as opposed to gastric glands, are completely lined with ________.

mucous cells

Which layer of the alimentary canal is responsible for segmentation and peristalsis?

muscularis externa Contractions of the circular and longitudinal layers of the muscularis externa produce the effects of peristalsis and segmentation. In the stomach, an additional muscle layer adds a twisting action.

What is a major function of pancreatic juice?

neutralizing chyme entering the small intestine from the stomach Pancreatic juice contains bicarbonate (as baking soda does) that can neutralize the pH of acidic chyme coming from the stomach.

Wavelike smooth muscle contractions that move foodstuffs through the alimentary tube.

peristalsis

Which of the following is NOT a means of mechanically breaking down food?

peristalsis Peristalsis is a physical process used for propulsion, or movement, through the GI tract.

What event triggers the opening of the gastroesophageal sphincter?

peristalsis in the esophagus As the peristaltic wave triggered by deglutition reaches the stomach, the gastroesophageal sphincter relaxes and allows food into the stomach.

The uvula is an extension of the __________.

soft palate The uvula extends out from and past the soft palate area of the palatopharyngeal arch.

Which layer of the alimentary canal contains not only glands and blood vessels but also a nerve plexus that helps regulate digestive activity?

submucosa The submucosa layer contains blood and lymphatic vessels, lymphoid follicles, and the submucosal plexus of nerve fibers.

The palatine tonsils are located between which two structures?

the palatopharyngeal arch and the palatoglossal arch The palatine tonsils are located along the lateral margins of the oral cavity between the palatopharyngeal arch and the palatoglossal arch.

As wastes navigate the large intestine, which features do they pass through, in order?

the right colic, left colic, and sigmoid flexures Materials pass the cecum and then the right colic, left colic, and sigmoid flexures on their way to the rectum and anus.

The mucosa of the appendix contains masses of lymphoid tissue (MALT) and therefore leukocytes capable of attacking bacteria are present in the appendix. During appendicitis, bacteria trapped in the lumen of the appendix are not effectively attacked because ______.

there is an inadequate blood supply to the appendix wall Immune cells must move from the blood into infected tissues when an immune response is needed to fight off invading bacteria, viruses, or protozoa.

Impacted wisdom teeth is a problem that is never observed in children because ______.

they lack third molar teeth Wisdom teeth normally emerge between the ages of 17 and 25 years.

The absorptive effectiveness of the small intestine is enhanced by increasing the surface area of the mucosal lining. Which of the following accomplish this task?

villi, and microvilli

The __________ is the serous membrane that covers most digestive organs.

visceral peritoneum The visceral peritoneum covers the external surfaces of most digestive organs and is continuous with the parietal peritoneum that lines the body wall.

Which of the following is the primary physiological function of the large intestine?

water absorption and feces elimination Though most water is absorbed in the small intestine, the absorption of most remaining water and the elimination of feces are the primary physiological functions of the large intestine. The large intestine also provides a transport route and a surface for healthful bacteria.