Chapter 22: The Digestive System
From deep (innermost) to superficial (outermost), the layers of the organs of the alimentary canal are:1. mucosa2. muscularis externa3. serosa (adventitia)4. submucosa
1, 4, 2, 3
Why might the drug orlistat, which blocks pancreatic lipase, helps an individual lose weight?
Blocking pancreatic lipase will, in turn,, block the chemical digestion and absorption of lipids, potentially leading to weight loss.
Which of the following intestinal hormones stimulates the release of bile from the gall bladder?
CCK (cholecystokinin)
Why would a disorder of the digestive system disrupt homeostasis?
The digestive system plays a critical role in many physiological processes that contribute to the maintenance of homeostasis, including supplying dietary nutrients, absorbing water, minerals, and vitamins for healthy body tissues, and eliminating wastes.
What is accomplished by the enterogastric reflex?
The enterogastric reflex decreases vagal activity and acid secretion by the stomach.
What cells compose the liver lobules?
hepatocytes
The pattern of slow, rhythmic contractions of the small intestine during fasting is called the __________.
migrating motor complex (MMC)
What best exemplifies enzymatic hydrolysis?
nutrient breakdown
Inactive precursors to enzymes are released by this organ to catalyze reactions that digest proteins in the small intestine
pancreas
Which of the following is not part of the gastrointestinal (GI) tract?
pancreas
Acinar cells of the pancreas release:
pancreatic juice
Which of the following enzymes is important for the digestion of fat?
pancreatic lipase
Which nervous system primarily controls and increases salivation?
parasympathetic nervous system
Proton-pump inhibitors are drugs that block the secretions of gastric acids. Which cells are affected by these drugs?
parietal cells
Which cells release hydrochloric acid (HCl) into the stomach?
parietal cells
Which of the following enzymes is important for breaking down protein?
pepsin
Which of the following is paired incorrectly?
pepsin - oligopeptides
Chief cells release:
pepsinogen.
Enzymatic breakdown of which of the following compounds doesn't begin until it reaches the stomach?
proteins
In what portion of the gastrointestinal tract does most salt and water absorption occur?
small intestine
Lipids are assembled into triglycerides and packaged into chylomicrons within enterocytes of this organ
small intestine
Most nutrient absorption in the GI tract occurs in the __________.
small intestine
Hormone produced by a diffuse neuroendocrine system (DNES) cell of the stomach to inhibit acid secretion by the stomach
somatostatin
Which of the following is NOT an effect of the vagus nerve on the stomach's activities?
stimulation of somatostatin secretion
The enzyme pepsin catalyzes reactions that digest proteins in this organ
stomach
Norepinephrine is the neurotransmitter released by which fibers?
sympathetic postganglionic fibers
Which cranial nerve stimulates acid secretion during the stomach's gastric phase?
vagus nerve
What creates the mesentery?
visceral peritoneum
There are methods of treating and living with celiac disease. Select the treatment method that you think would be most beneficial.
A gluten-free diet
What is the primary effect of gastric-inhibitory peptide (GIP)?
GIP inhibits acid secretion from parietal cells.
Would bile salts be effective if they were polar molecules instead of amphiphilic molecules?
If bile salts were polar molecules they would be ineffective because they would not be able to interact with lipids.
Which antibody class is secreted by the salivary glands?
IgA
bilirubin
When red blood cells are old or injured, the spleen breaks them down and converts the heme from their hemoglobin into
cholecytokinin
When you eat fat, the cells of your small intestine release the hormone
Where are the enzymes for digestion of disaccharides and small polypeptides located?
brush border
Before carbohydrates are absorbed, __________ digest disaccharides into monosaccharides.
brush border enzymes
The esophagus empties into the __________ region of the stomach.
cardia
What region of the stomach does food first enter after its passage through the relaxed gastroesophageal sphincter?
cardia
The first portion of the large intestine is the:
cecum
Which of the following is a source of dietary fiber and promotes timely movement through the colon?
cellulose
The smell of croissants in a bakery would trigger the __________ phase of gastric secretion.
cephalic
Voluntary relaxation of the external anal sphincter that triggers defecation is controlled by the __________.
cerebral cortex
HCl secretions convert pepsinogen to the active hormone pepsin. What cells in the gastric pits produce pepsinogen?
chief
Hormone released by the duodenum in response to lipids and partially digested proteins in the duodenum
cholecystokinin (CCK)
Which hormone stimulates the acinar cells of the pancreas to secrete digestive enzymes?
cholecystokinin (CCK)
What does the gastric pacemaker regulate?
churning and peristalsis of the stomach
The largest folds in the small intestine are the __________.
circular folds (plicae circulares)
The portion of a tooth that is visible above the gum line is known as the:
crown
Gallstones may block the flow of bile from the gallbladder by becoming lodged in the:
cystic duct.
What is NOT a major function of the normal flora of the large intestine?
inhibit the immune system
The sympathetic nervous system:
inhibits digestive processes.
During which phase in the control of the digestive system would bicarbonate and bile be stimulated?
intestinal phase
Cherise is lactose-intolerant because she produces insufficient amounts of an enzyme called:
lactase
Which enzyme catalyzes the reaction of lactose into glucose and galactose?
lactase
Which organ functions to absorb significant quantities of water, electrolytes, and vitamins?
large intestine
The most inferior division of the pharynx is the __________.
laryngopharynx
The gallbladder is located on the posterior side of the:
liver
The hepatic portal vein takes the breakdown products of nucleic acids to this organ for metabolism
liver
What creates the taeniae coli?
longitudinal layer of the muscularis externa
Which of the following is NOT a major job of the digestive system?
manufacturing blood cells
Peristaltic contractions that propel the contents of the colon toward the distal large intestine are:
mass movements.
Which modification of the small intestine creates a brush border appearance upon microscopic examination?
microvilli
Damage to the enteric nervous system that innervates the digestive organs could affect:
motility.
The enzyme salivary amylase catalyzes the reactions that break polysaccharides into oligosaccharides in this organ
mouth
Absorption is best described as the:
movement of food particles through the wall of the alimentary canal.
Jerry had an ulcer affecting the innermost epithelium of the stomach facing the lumen. Which layer of the alimentary canal was ulcerated?
mucosa
What do goblet cells secrete?
mucus
Many chemotherapy treatments for cancer kill rapidly dividing cells. What happens to a patient's digestive system on this kind of treatment?
Chemotherapy treatments will reduce the ability of the mucosa to maintain its epithelial lining.
What would happen with the defecation reflex if the spinal cord were damaged?
Defecation would no longer be under voluntary control since the cerebral cortex would not be able to communicate with the external anal sphincter and levator ani muscle.
Which of the following is a protective function of the liver related to absorption of chemicals found in the body?
Detoxification.
Celiac disease can also cause more significant issues in the digestive system. Based on your knowledge of the function of the small intestine, which of the following do you think may occur as a result of the resulting inflammation and damage to the lining of the small intestine?
Loss of the villi surface area and a decrease in absorption of nutrients, causing malabsorption.
What enzyme is responsible for digesting emulsified fats?
Pancreatic lipase
Which of the following enzymes digests proteins?
Pepsin
In celiac disease, gluten found in wheat products triggers an inflammatory response in the mucosal lining of the small intestine, disrupting the structure and function of villi. Loss of villi would be expected to have the greatest impact on nutrient absorption in which division of the small intestine?
The jejunum.
Choose the answer that best describes the liver's role in lipid digestion.
The liver creates bile, a soapy compound that emulsifies lipids.
Gallbladder
The liver further converts it into bile
What is the first process to occur in the digestive system?
ingestion
Why are patients encouraged to take supplements that contain bacteria found in the natural flora when they are on antibiotics?
Antibiotics often destroy the natural flora of bacteria in the large intestine which can lead to greater infections.
A blood test that can be used to see if celiac disease is possible is the tissue transglutaminase (tTG)-IgA antibodies (tTG-IgA test). Why do you think this test is a good tool as a screening for possible celiac disease?
Antibodies are produced by B cells of the immune system in response to specific antigens. In celiac disease, the immune system recognizes gluten as an allergen and produces antibodies against it.
Persistent diarrhea is a common complaint of both celiac disease and Crohn's disease. Which of the following statements best describes how large intestine motility and diarrhea are related?
Any event that increases large intestine motility does not allow enough time to absorb excess water from fecal material.
Which of the following sphincters is voluntary?
External anal sphincter
The terminal portion of the large intestine is the rectum.
False
Which of the following functions is not associated with the digestive system?
Filtration
Celiac disease affects the small intestine. The immune system attacks the gluten protein found in wheat, rye and barely, and also damages the lining of the small intestine. What is the primary function of the small intestine?
It produces and secretes most enzymes needed for chemical digestion.
What effect would a poison that stimulates the parasympathetic nervous system, by activating the vagus nerve; have on the motility of the stomach?
Much of the churning of the stomach is under the control of hormones and enteric nervous system (ENS) neurons so this poison would have little effect on these control mechanisms.
Certain diseases, such as Parkinson's disease, will weaken the swallowing reflex and decrease the muscularis externa activity in the esophagus. What is one type of complication that can result?
Patients with Parkinson's disease may aspirate their food because the swallowing reflex may not properly trigger the elevation of the larynx.
Which digestive processes are missed by a patient who has a feeding tube placed in their stomach?
Patients with feeding tubes placed in their stomachs will not go through mastication and the initial chemical digestion of carbohydrates.
Why would a pharmacist recommend a patient with liver damage to be given a lower dose of medication over a longer period than what the doctor originally prescribed?
Patients with liver disease metabolize drugs slower and they remain in the system longer than individuals with normal liver function.
Which of the following statements about digestive system processes is true?
Peristalsis involves rhythmic contractions that are not only involved in propulsion, but also aid in mechanical digestion in some segments of the alimentary canal.
Chronic gastritis affects the normal function of the cells found in the gastric pits. Which of the following events revolving around hydrogen ion secretion is NOT associated with the cephalic phase of digestion?
Presence of food in the stomach distends the stomach wall and stimulates acetylcholine release, increasing acid secretion.
What symptoms will a patient with pyloric stenosis (a narrowing due to hypertrophy of the pyloric sphincter) have?
Pyloric stenosis may cause a patient to experience excessive vomiting, leading to electrolyte imbalance and malnutrition.
What digestive functions would be affected by the removal of the pancreas from a patient with pancreatic cancer?
Removal of the pancreas would severely impact chemical digestion because the pancreatic juices contain multiple digestive enzymes needed to digest all types of nutrients.
Why would decreased saliva lead to tooth decay?
Saliva helps to moisten and cleanse the oral cavity and contains lysozymes and IgA to kill pathogenic bacteria, preventing tooth decay.
Why do chemical warfare agents (nerve gases) that block the enzyme acetylcholinesterase cause drooling in individuals affected by them?
Salivation is stimulated by the release of acetylcholine by the parasympathetic nervous system. If ACh cannot be broken down by acetylcholinesterase, excess salivation will occur.
What additional affects will a vagotomy (severing the vagus nerve) have on a patient, besides lowering stomach acid secretion?
Stomach acids are needed to activate pepsinogen so lower acid secretion will affect protein digestion in the stomach.
Which of the following functions is not associated with the liver?
Stores and concentrates bile
What will happen to supplemental digestive enzymes in the stomach after they are ingested?
Supplemental digestive enzymes are proteins and will be broken down in the stomach by the acids and pepsin, rendering them useless.
Why does peritonitis, inflammation of the peritoneal membrane, affect multiple digestive organs?
The peritoneal membrane surrounds many abdominal organs, so inflammation of the membrane will affect multiple organs rapidly.
From large to small, the types of folds associated with the small intestine are circular folds, villi, and microvilli.
True
The internal anal sphincter is controlled involuntarily while the external anal sphincter is controlled voluntarily.
True
The vagus nerve appears to regulate both peristalsis and segmentation in the small intestine.
True
Celiac disease disrupts the absorption of all of the macronutrients, which include lipids, carbohydrates, and proteins. Which of the following events is NOT associated with lipid absorption in the small intestine?
Trypsinogen is converted to active trypsin.
Enteric interneurons that are inhibitory to smooth muscle use which of the following neurotransmitters?
VIP (vasoactive intestinal peptide)
Which of the following vitamins is absorbed in the ileum after binding to intrinsic factor?
Vitamin B12
A patient has been taking large doses of diphenhydramine, an over-the-counter antihistamine medication, for a severely pruritic (itchy) skin rash. The medication has caused her to develop a very dry mouth (xerostomia). Which of the following statements inaccurately describes how xerostomia would affect a process associated with saliva?
Xerostomia would lead to a dramatic increase in Hydrogen ions (H+) that are added to saliva as a means for neutralizing bicarbonate ions that may be regurgitated into the esophagus during eating.
Celiac disease is caused by an allergy to gluten, a protein found naturally in some grains. The disease damages the lumen of the small intestine, specifically the villi and microvilli. Several symptoms associated with celiac disease would be
abdominal bloating and pain, chronic diarrhea due to excess unabsorbed water, and weight loss.
Splanchnic circulation involves the blood supply that feeds and drains:
abdominal digestive organs.
Which process is NOT a main function of the stomach?
absorption
Which of the following does NOT transport bile?
accessory pancreatic duct
In response to a steak dinner, certain secretions are needed to aid digestion. What cells in the pancreas would provide these secretions?
acinar cells
A molecule of glucose being absorbed in the small intestine will first be transported __________.
across the apical membrane of enterocytes
Which is not an endocrine hormone secreted by the pancreas?
aldosterone
The conversion of pepsinogen into the active form, pepsin, requires:
an acidic pH.
The secretion in the large intestine consists of which of the following?
bicarbonate- and potassium-rich mucus
What liver secretion is responsible for the emulsification of lipids in the duodenum?
bile
Damaged hepatocytes will impair:
bile production.
What is the most potent stimulus for a positive feedback loop that results in the release of bile by the liver?
bile salt re-entry into the liver
Emulsification requires:
bile salts.
The removal of the gallbladder will affect:
bile storage.
A disease that attacks and disables the myenteric plexus would:
decrease the motility of muscularis externa.
The final process to occur in the alimentary canal is:
defecation
Mary's stroke left her unable to swallow. What specialized type of propulsion was affected?
deglutition
At the splenic flexure, the colon becomes the:
descending colon.
In which organ is chyme mixed with pancreatic juice and bile?
duodenum
Which segment of the small intestine receives chyme from the stomach?
duodenum
The pancreatic juices transported in the main pancreatic duct are destined for the:
duodenum.
The crown of a tooth is covered by:
enamel
Which nervous system controls the migrating motor complex of the small intestine?
enteric nervous system
Which of the following is an organ of the alimentary canal?
esophagus
Which of the following operates voluntarily and is controlled by the cerebral cortex?
external anal sphincter
How is fructose absorbed across the apical enterocyte membrane?
facilitated diffusion
The breakdown products of which of the following are absorbed into lacteals?
fats
Salivation is controlled almost entirely by the nervous system. Which of the following stimuli would inhibit salivation?
fear
Which of the following tongue papillae do not contain taste buds?
filiform
Which tongue papillae lack taste buds?
filiform
Contraction of galbladder
forces the bile into the duodenum, where it emulsifies fats and aids in their digestion.
Hormone produced by the duodenum to reduce acid secretion by the stomach
gastric-inhibitory peptide (GIP)
Hormone produced by a diffuse neuroendocrine system (DNES) cell of the stomach called a G cell
gastrin
What is released by the diffuse neuroendocrine system (DNES) cells of the gastric glands?
gastrin
Which hormone increases acid secretion by the stomach?
gastrin
In the small intestine, which of the following enzymes breaks down oligosaccharides?
glucoamylase
What separates the oral cavity from the nasal cavity?
hard palate and soft palate
Most digestive enzymes catalyze __________ reactions.
hydrolysis
What prevents bacteria and materials in the large intestine from flowing backward into the ileum of the small intestine?
ileocecal valve
What is the final segment of the small intestine?
ileum
Villi in the small intestine ________________.
increase the surface area for absorption
Sjögren's syndrome is an autoimmune disorder in which the body's white blood cells attack and destroy exocrine glands, specifically the salivary glands. What could a patient with this syndrome expect?
increased risk of dental cavities, or caries
What region of the esophagus is composed of smooth muscle only?
inferior third of the esophagus
The function of lysozyme in saliva is to __________.
perforate bacterial plasma membranes
The bolus is able to move down the esophagus even if you are upside-down, because of __________.
peristalsis
Ben had most of his stomach removed in an attempt for drastic weight loss. He is at the greatest risk for:
pernicious anemia.
During the Gastric phase, which of the following is a trigger for gastrin release?
presence of partially digested proteins in gastric juice
What is the main job of the pharynx?
propulsion
The digestion of which food group may be affected by an inadequate amount of stomach acid?
proteins
Since her stomach was removed, Mrs. Lopez has the most difficulty initiating digestion of:
proteins.
What controls the passage of chyme from the last region of the stomach to the duodenum region of the small intestine?
pyloric sphincter
What can we consciously control about the defecation reflex?
relaxation of the external anal sphincter
The falciform ligament separates the:
right and left lobes of the liver.
Which of the following does NOT increase surface area in the small intestine?
rugae
Rolita had the mumps as a child and experienced swelling in the parotid glands. What do these glands secrete?
saliva
What enzyme catalyzes reactions that initiate carbohydrate digestion?
salivary amylase
Which of the following catalyzes carbohydrates in the mouth?
salivary amylase
An increase in HCl (hydrochloric acid) arriving in the duodenum would stimulate which hormone that would help to counteract the effects of HCl?
secretin
Hormone released by the duodenum in response to acids and lipids in the duodenum
secretin
Which of the following GI hormones promotes a pancreatic juice rich in bicarbonate ions?
secretin
Which of the following is NOT a process occurring in the oral cavity?
segmentation
Which process, known as intestinal churning, involves a squeezing motion of the circular layer of smooth muscle in the small intestine?
segmentation
During the swallowing reflex __________.
the epiglottis closes off the glottis
What stimulus initiates the defecation reflex?
the stretch of the rectum
The first sphincter encountered in the alimentary canal is the:
upper esophageal sphincter.
