Ch.23 Digestive System Part 2

Which of these best describes a lacteal? a deep pocket in the intestinal wall where endocrine and antimicrobial cells are located special blood capillaries in the villi designed for absorbing food effectively

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 enzymes is important for the digestion of fat? pancreatic amylase pepsin trypsin pancreatic lipase

pancreatic lipase Yes, pancreatic lipase is important for the digestion of fats. It is secreted by the pancreas and works in the small intestine.

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 vast array of digestive enzymes Brunner's glands and Peyer patches the rugae and haustra

villi, and microvilli

Which of the following is the primary physiological function of the large intestine? Flexures and external structures of the large intestine. nutrient absorption water absorption and feces elimination primary digestion of food mechanical breakdown of food

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.

The formation of diverticula involves, most significantly, the ______. atrophy of the muscularis externa atrophy of the mucosa weakening of the colon's submucosa thickening of the serosa

weakening of the colon's submucosa The submucosa is composed of dense connective tissue containing elastic fibers, blood and lymphatic vessels, lymph nodes, and nerves.

The human GI tract is home to a complex ecosystem of microbial cells, which comprise the gut microbiota. Which of the following is true of the microbiota? Generally, the highest concentration of GI tract microbes is found in the colon. Metabolism by the gut microbiota results in small amounts of vitamins and short-chain fatty acids which can be absorbed and utilized by cells of the body. Normally, beneficial bacteria vastly outnumber harmful bacteria in the microbiota. All of the above.

All of the above. Review information about the bacterial microbiota in your textbook.

Which of the following is a source of dietary fiber and promotes timely movement through the colon? polypeptides cellulose triglycerides amylase

Cellulose Yes, the polysaccharide cellulose is not digested and is used as a source of dietary fiber.

__________ can result if food passes too slowly through the large intestine. Colitis Constipation Diarrhea Irritable bowel syndrome

Constipation When food remains in the colon for extended periods, too much water is absorbed and the stool becomes hard and difficult to pass. This condition, called constipation, may result from insufficient fiber or fluid in the diet, improper bowel habits (failing to heed the "call"), lack of exercise, or laxative abuse.

Which is NOT true of lipid absorption? Enterocytes require the presence of lipoprotein lipase to effectively absorb micelles. Fatty acids and monoglycerides are packaged with proteins to form chylomicrons. Products of lipid digestion are transported to the blood by the lymphatic system. Fatty acids and monoglycerides are absorbed passively by diffusion.

Enterocytes require the presence of lipoprotein lipase to effectively absorb micelles.

The submucosal nerve plexus provides the major nerve supply to the GI tract wall and controls GI motility. True False

False

Bacteria that reside in the large intestine make vitamin C. True False

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.

The breakdown products of which of the following are absorbed into lacteals? proteins carbohydrates fats

Fats Yes, chylomicrons are absorbed into lacteals because they are too large to pass through the basement membrane of a capillary and into the blood.

Select the correct statement about absorption. Amino acid transport is linked to chloride transport. Carbohydrates diffuse across the mucosal endothelium and are then actively transported into blood capillaries. Eighty percent of ingested materials have been absorbed by the end of the large intestine. In the rare case that intact, whole proteins are transported across the mucosal endothelium, an immune response may be generated.

In the rare case that intact, whole proteins are transported across the mucosal endothelium, an immune response may be generated.

Which of the following is NOT characteristic of the large intestine? It has pocket-like sacs called haustra. It does not contain villi. It is longer than the small intestine. It exhibits external muscular bands called teniae coli

It is longer than the small intestine.

Which of the following enzymes is important for breaking down protein? amylase lipase pepsin bile salts

Pepsin Yes, pepsin breaks down proteins in the stomach.

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 alkaline secretions of the small intestine aid in the growth of bacteria and these bacteria must be controlled. The digestive systems first and foremost job is to digest and absorb nutrients so it puts off immunity for last. 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. The body will actively excrete pathogens out of the body, into the digestive system, to be removed from the body in feces.

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.

An ileostomy is a surgical opening (stoma) constructed by bringing the ileum to the skin and attaching it there, thus bypassing the colon and rectum entirely. A colostomy is created by bringing a part of the colon to the body surface. Which of the following might occur for a person who has had an ileostomy or colostomy? A person with an ileostomy or ascending colostomy would have very firm bowel movements. A person with a descending colostomy would have a stoma on the right side of the abdomen. The stoma (i.e., the surgical opening created at the body surface) will normally look red and moist. A person with a descending colostomy would normally have watery bowel movements.

The stoma (i.e., the surgical opening created at the body surface) will normally look red and moist. The stoma will be red and moist, in contrast to the appearance of skin, because the intestinal wall is brought to the body surface and the mucosal lining is exposed there.

Most nutrients are absorbed through the mucosa of the intestinal villi by active transport. True False

True

The circular folds of the small intestine enhance absorption by causing the chyme to spiral, rather than to move in a straight line, as it passes through the small intestine. True False

True

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

True

The end products of protein digestion are transported across the apical membranes of enterocytes by __________. phagocytosis diffusion osmosis active transport

active transport Amino acids, the end products of protein digestion, are transported across the apical membranes of enterocytes via cotransport with sodium. This form of transport is called secondary active transport; while one substance (amino acid) is moving against its concentration gradient the other (sodium) is moving down its concentration gradient—thereby providing the energy to run the transporter and move both substances in the same direction.

You have just eaten a meal high in complex carbohydrates. Which of the following enzymes will help to digest the meal? cholecystokinin amylase gastrin trypsin

amylase

Which enzyme(s) is/are responsible for the chemical breakdown of carbohydrates? proteases amylases nuclease trypsin

amylases Amylases hydrolyze carbohydrate chains.

Where are the enzymes for digestion of disaccharides and small polypeptides located? stomach saliva brush border secretions from the pancreas

brush border Yes, the enzymes for digestion of disaccharides and small polypeptides are found in the brush border of most the absorptive cells of the small intestine.

How are vitamins A, D, E, and K absorbed by the body? by binding to intrinsic factor to trigger receptor-mediated endocytosis by being incorporated into micelles by active transport of vitamin pumps in the intestinal epithelia by direct simple diffusion in the jejunum

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.

What structural modification of the small intestine slows the movement of chyme through the lumen? villi intestinal crypts microvilli circular folds

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.

Which of the following is not an important contribution of the bacterial microbiota found in the large intestine? vitamin synthesis fermentation of carbohydrates suppress the growth of harmful bacteria digestion of proteins

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

When the diet lacks fiber and the volume of residues in the colon is small, the colon narrows and its contractions become more powerful, increasing the pressure on its walls. This promotes formation of __________. diverticula cystic fibrosis gallstones irritable bowel syndrome (IBS)

diverticula When the diet lacks fiber and the volume of residues in the colon is small, the colon narrows and its contractions become more powerful, increasing the pressure on its walls. This promotes formation of diverticula, small herniations of the mucosa through the colon walls. This condition, called diverticulosis, most commonly occurs in the sigmoid colon, and affects over half of people over age 70. In 4-10% of cases, diverticulosis progresses to diverticulitis, in which the diverticula become inflamed and may rupture, leaking into the peritoneal cavity, which can be life-threatening.

In the small intestine, which of the following enzymes breaks down oligosaccharides? sucrase lactase pancreatic amylase glucoamylase

glucoamylase Yes, glucoamylase breaks down oligosaccharides.

Which cells in the small intestine's mucosa secrete mucus? absorptive cells Paneth cells goblet cells enteroendocrine cells

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.

What is the condition called where a proximal portion of the stomach pushes through an opening in the diaphragm, allowing stomach acid to pass into the esophagus? hiatal hernia esophageal varices dyspepsia dysphagia

hiatal hernia

In cystic fibrosis, blockage of the pancreatic duct by thick mucus will prevent the flow of pancreatic juice into the duodenum; this will directly cause ______. backup of pancreatic juice into the liver via the bile duct hyposecretion of pancreatic hormones impaired digestive function due to lack of pancreatic enzymes decreased motility of the small intestine

impaired digestive function due to lack of pancreatic enzymes The pancreatic acini function to secrete pancreatic juice and enzymes. Blockage of the the ducts will greatly impair the chemical digestion of many types of foods in the duodenum.

In what form do fats first enter the bloodstream? in the form of chylomicrons in the form of micelles in the form of glycerol in the form of fatty acids and glycerol

in the form of chylomicrons Within enterocytes, fats are combined with phospholipids and cholesterol, and coated with proteins to form water-soluble lipoprotein droplets called chylomicrons. Chylomicrons are secreted first into lymphatic vessels where they are eventually emptied into the bloodstream.

One of the direct consequences of lactose intolerance is ______. increased intestinal absorption of this disaccharide increased osmotic pressure of the large intestine contents decreased motility of the small and large intestines increased blood glucose levels

increased osmotic pressure of the large intestine contents Osmosis is the diffusion of water (down its concentration gradient) across a semipermeable membrane. Recall that the rate and direction of osmosis is dictated by the concentration of non-diffusible solutes in a solution.

Chyme entering the large intestine normally consists of __________. indigestible fiber, enteric bacteria, and water large proteins, nucleic acids, and other molecules not generally utilized as an energy source excess nutrients that the body does not need all fat-soluble molecules that are unable to cross the small intestine epithelium

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.

An effective way to medically treat diarrhea would be to use a drug that ______. increases the activity of the longitudinal layer of the muscularis increases the activity of the parasympathetic division of the ANS inhibits muscle tone in the anal sphincters inhibits the activity of the myenteric nerve plexus

inhibits the activity of the myenteric nerve plexus The myenteric nerve plexus is the major nerve supply that controls gastrointestinal tract motility.

A ruptured appendix is life threatening because ________. it is likely to cause severe internal bleeding the large intestine will no longer be able to receive digested material from the small intestine loss of the appendix's function will cause an immune deficiency in the digestive system it is likely to cause massive infection of the abdominopelvic cavity

it is likely to cause massive infection of the abdominopelvic cavity

Most absorption of nutrients occurs in the __________. descending and sigmoid colon jejunum and ileum cecum and ascending colon stomach and duodenum

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.

Short-chain triglycerides found in foods such as butterfat molecules in milk are split by a specific enzyme in preparation for absorption. Which of the following enzymes is responsible? pepsin lipase amylase chymotrypsin

lipase

Bile salts break up the fat globule into smaller fat droplets. This role of bile salts is best described as ________. lipid ingestion lipid absorption lipid digestion lipid emulsification

lipid emulsification

When a baby ingests breast milk, the milk's IgA antibodies may be absorbed into the baby's bloodstream because ______. many pepsinogen molecules remain unchanged the antibodies specifically trigger pinocytosis (also called fluid-phase endocytosis) by the intestinal epithelial cells the baby's duodenal mucosa has not yet initiated its gastric acid secretion the antibody molecules have binding sites capable of binding to blood-borne antigens

many pepsinogen molecules remain unchanged Pepsinogen is the inactive form of the enzyme pepsin. Pepsin functions to initiate the breakdown of proteins.

Which of the following propels food residue over large areas of the colon three to four times a day? Flexures and external structures of the large intestine. haustral contractions mass movement defecation reflex Valsalva's maneuver

mass movement Mass movement propels food residue over large areas of the colon three to four times a day. The defecation reflex occurs when the rectal wall stretches as mass movements force feces into it.

Carbohydrates are digested into __________. monosaccharides nucleotides amino acids glycerol

monosaccharides Monosaccharides are simple sugars, the building blocks of complex carbohydrates such as starch or glycogen.

Which of the following is NOT an effect of aging on digestive system activity? more frequent bowel movements less efficient absorption fewer digestive juices are produced slowing of peristalsis

more frequent bowel movements During old age, GI tract activity declines. This results in less frequent (not more frequent) bowel movements. In addition, fewer digestive juices are produced, absorption is less efficient, and peristalsis slows.

Fat absorption through the plasma membrane of epithelial cells ________. requires vesicular, active transport of the relatively large fatty acids and monoglyceride occurs by simple diffusion because lipids are able to penetrate the hydrophobic fatty acid tails within the plasma membrane requires enzymes attached to the brush border to further breakdown the fats is accomplished by cotransporters that use the concentration gradient of Na+ outside of the cells

occurs by simple diffusion because lipids are able to penetrate the hydrophobic fatty acid tails within the plasma membrane

An individual diagnosed with celiac disease would be prescribed a gluten-free diet in order to __________. prevent inflammation caused by malabsorption of gluten protein reduce absorption of dietary fats increase vitamin absorption reduce absorption of high-calorie dietary carbohydrates

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.

The function of goblet cells is to ________. provide protection against invading bacteria and other disease-causing organisms that enter the digestive tract in food produce mucus that protects parts of the digestive organs from the effects of powerful enzymes needed for food digestion absorb nutrients from digested food and store them for future use secrete buffers in order to keep the pH of the digestive tract close to neutral

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

Which of the following are NOT correctly matched? amylase: carbohydrate digestion nuclease: DNA and RNA digestion lipase: fat digestion protease: lipid digestion

protease: lipid digestion Proteases digest proteins.

Enzymatic breakdown of which of the following compounds doesn't begin until it reaches the stomach? proteins lipids carbohydrates

proteins Yes, enzymatic breakdown of proteins begins in the stomach.

Which of the following is NOT a structural modification of the small intestine that increases surface area? rugae circular folds microvilli villi

r Rugae are a structural modification that allow expansion of the stomach wall. Three structural modifications of the small intestine—circular folds, villi, and microvilli—amplify its absorptive surface enormously (by a factor of more than 600 times). The result is an intestinal surface area equal to about 200 square meters, the size of a singles tennis court!

Paneth cells ________. secrete bicarbonate ions secrete digestive enzymes secrete enzymes that kill bacteria secrete hormones

secrete enzymes that kill bacteria

Which of the following is not a common risk factor for acid reflux disease? sitting upright after a meal being overweight or obese eating fatty or spicy foods snacking near bedtime

sitting upright after a meal

Absorption of nutrients primarily occurs in the __________. mouth stomach large intestine small intestine

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

In what portion of the gastrointestinal tract does most salt and water absorption occur? stomach small intestine colon mouth

small intestine Yes, most absorption of salt and water occur in the small intestine.

Which other organ can affect small-intestine motility? large intestine stomach pancreas mouth

stomach As the stomach releases its contents into the small intestines, enterogastric reflexes and gastrin released by the stomach affect the motility of the small intestine.

Which of the following is NOT a function of the large intestine? synthesis of intrinsic factor absorption of water absorption of electrolytes synthesis of vitamins

synthesis of intrinsic factor Intrinsic factor is produced in the stomach; it is required for absorption of vitamin B12 in the small intestine.

Which of the following is an essential role played by large intestine bacteria? synthesis of vitamin K synthesize vitamins C and D absorb bilirubin produce gas

synthesis of vitamin K

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 ______. these bacteria are resistant to attack these bacteria are not resistant but they are immune to attack by the leukocytes there is an inadequate blood supply to the appendix wall feces provide protection to the bacteria

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.

Which of the following enzymes would be most active in the presence of high concentrations of protein fragments? trypsin dextrinase lipase amylase

trypsin