Chapter 23 Digestive System
Chemical or mechanical process of breaking down foodstuffs to substances that can be absorbed
Digestion
The ________ phase of gastric secretions occurs before food enters the stomach
cephalic or reflex
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 ________.
chemical digestion
Pepsinogen, a digestive enzyme, is secreted by the ________.
chief cells of the stomach
Chemical digestion in the small intestine involves ________.
cholecystokinin (CCK), an intestinal hormone responsible for gallbladder contraction
Which hormone causes an increased output of enzyme-rich pancreatic juice and stimulates gallbladder contraction to release bile?
cholecystokinin CCK
The function of the hepatic portal circulation is to ________.
collect absorbed nutrients for metabolic processing or storage
Which of the following is not true of saliva?
contains enzymes that begin the breakdown of proteins
Pancreatic amylase does not get to the small intestine via the ________.
cystic duct
The chemical and mechanical processes of food breakdown are called ________.
digestion
The solutes contained in saliva include ________.
electrolytes, digestive enzyme, mucin, lysozyme, wastes, and IgA
What part of the tooth bears the force of chewing?
enamel
The mucosa of the developing alimentary tube comes from ________
endoderm
Gastrin, histamine, endorphins, serotonin, cholecystokinin, and somatostatin are hormones or paracrines that are released directly into the lamina propria. Which of the following cell types synthesize and secrete these products?
enteroendocrine cells
Which of the following is not a phase of gastric secretion
enterogastric
Which of the following are types of papillae on the tongue that contain taste buds?
fungiform and circumvallate
The ducts that deliver bile and pancreatic juice from the liver and pancreas, respectively, unite to form the ________.
hepatopancreatic ampulla
Parietal cells of the stomach produce ________
hydrochloric acid
The enzymatic breakdown of any type of food molecule is called ________.
hydrolysis
The longest portion of the small intestine is the ________.
ileum
The terminal portion of the small intestine is known as the ________.
ileum
The mechanical and chemical receptors that control digestive activity are located ________.
in the walls of the tract organs
Which of these is not part of the splanchnic circulation?
inferior vena cava
In addition to storage and mechanical breakdown of food, the stomach ________.
initiates protein digestion and denatures proteins
What stomach secretion is necessary for normal hemoglobin production in RBCs?
intrinsic factor
Which of the following is not characteristic of the large intestine? It ________.
is longer than the small intestine
The capillaries that nourish the epithelium and absorb digested nutrients lie in the ________.
lamina propria
You have just eaten french fries, buttered toast, ice cream, and whole milk. Which of the following glands would be active in helping you to digest this food
the pancreas
Surgical cutting of the lingual frenulum would occur in which part of the body?
tongue
Which of the following enzymes is specific for proteins?
trypsin
The round ligament is a remnant of the fetal ________.
umbilical vein
Peristaltic waves are ________.
waves of muscular contractions that propel contents from one point to another
Chyme is created in the ________
stomach
Only digestive structure with three muscle layers
stomach
Produces a mucoid barrier
stomach
Produces intrinsic factor.
stomach
Which of the following is an essential role played by large intestine bacteria?
synthesize vitamin K and B-complex vitamins
The function of the goblet cells is to ________.
) produce mucus that protects parts of the digestive organs from the effects of powerful enzymes needed for food digestion
The layer of the digestive tube that contains blood vessels, lymphatic nodes, and a rich supply of elastic fibers is the ________.
) submucosa
) Nervous control of gastric secretion is provided by ________.
) the vagus nerve and enteric plexus
Chemical digestion reduces large complex molecules to simpler compounds by the process of ________.
catabolism
A fluid secreted into the small intestine during digestion that contains cholesterol, emulsification agents, and phospholipids is ________.
bile
The chief bile pigment is ________
bilirubin
Process by which the products of digestion pass through the lumen of the gastrointestinal tract into the blood or lymph.
Absorption
________ is the principal enzyme for breaking down carbohydrates.
Amylase
Which vitamin requires intrinsic factor in order to be absorbed?
B12
Choose the incorrect statement regarding bile.
Bile contains enzymes for digestion.
What is bile and where is it produced? What is its digestive function? Where is it stored and concentrated?
Bile is an alkaline solution containing bile salts, bile pigments, cholesterol, neutral fats, phospholipids, and a variety of electrolytes. It is produced in the liver. Its digestive function is to emulsify fats. It is stored and concentrated in the gallbladder.
The ingestion of a meal high in fat content would cause which of the following to occur?
Bile would be released from the gallbladder to emulsify the fat in the duodenum.
________ is locally regulated in the blood by the active form of vitamin D, which acts as a cofactor
Calcium
________ is (are) not important as a stimulus in the gastric phase of gastric secretion.
Carbohydrates
What are chylomicrons?
Chylomicrons are tiny fatty droplets composed of triglycerides, small amounts of phospholipids, cholesterol, free fatty acids, and some protein.
Select the correct statement about digestive processes.
Chyme entering the duodenum can decrease gastric motility via the enterogastric reflex
The dental formula for an adult is 2-1-2-
canine tooth
________ is another word for vomiting.
Emesis
Pepsinogen is the precursor to the gastric enzyme for protein digestion and is secreted by the parietal cells.
FALSE
The pharyngeal-esophageal phase of swallowing is involuntary and is controlled by the swallowing center in the thalamus and lower pons
FALSE
Dentin anchors the tooth in place
False
The soft palate rises reflexively to open the nasopharynx when we swallow food.
False
The stomach's contractile rhythm is set by pacemaker cells found in the spinal cord.
False
Select the correct statement about the regulation of gastric secretion.
Gastric secretion can be stimulated before food has entered the mouth.
Why is it necessary for the stomach contents to be so acidic? How does the stomach protect itself from digestion?
HCl is necessary for the activation and optimal activity of pepsin, and it kills many of the bacteria ingested with food. Mucous cells in the lining of the stomach secrete an alkaline mucus that clings to the stomach wall and helps to shield it from the acid. The epithelial cells of the mucosa are joined together by tight junctions that prevent gastric juice from leaking into underlying tissue layers. Damaged epithelial cells are shed and quickly replaced by cell division.
What is heartburn and what causes it?
Heartburn is the discomfort felt in the chest area when the acidic gastric juices get regurgitated into the esophagus. This may happen when someone has eaten or drunk too much, or it can be caused by extreme obesity or the discomfort of pregnancy. It is sometimes due to obstructions or structural faults in the esophagus as well
Enzymatic breakdown of any type of food molecule.
Hydrolysis
Select the correct statement about absorption
If intact proteins are transported across the villus epithelium, an immune response may be generated.
There are some 20 known pathogens found in the large intestine; our Ig ________ antibody-mediated response restricts them from going beyond the mucosa and causing problems.
IgA
Select the correct statement about electrolyte absorption.
Iron and calcium are absorbed mostly by the duodenum
________ cells are found in the sinusoids of the liver, and they remove debris from the blood as it flows past.
Kupffer
Name two regions of the digestive tract where mechanical food breakdown processes are very important. Name two organs that are primarily food conduits. Name the organ where protein digestion is begun. Name the organ where fat digestion begins.
Mechanical food processes are very important in the mouth (mastication) and stomach (contractions causing mixing of food into chyme). The esophagus and pharynx are primarily food conduits. Protein digestion begins in the stomach. Fat digestion begins in the small intestine.
) ________ cells of the stomach secrete HCl
Parietal
Wavelike smooth muscle contractions that move foodstuffs through the alimentary tube.
Peristalsis
Compare and contrast the structure and function of a premolar and a molar.
Premolars have a broad crown with rounded cusps but have only one root. Molars also have broad crowns with rounded cusps but are larger than premolars. Molars have at least two roots.
How is digestive activity provoked after eating? What activates the secretion of digestive juices into the lumen or hormones into the blood?
Sensors (mechanoreceptors and chemoreceptors) located in the walls of the gastrointestinal tract respond to stretching by the introduction of food into the lumen. Also, the sensors are able to respond to changes in solute concentration and pH as well as the presence of substrates and end products of digestion.
How are most nutrients absorbed through the mucosa of the intestinal villa?
active transport driven directly or indirectly by metabolic energy
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
Another term for swallowing is deglutition
TRUE
As food passes through the digestive tract, it becomes less complex and the nutrients are more readily available to the body
TRUE
Fats significantly delay the emptying of the stomach
TRUE
Food is contained in the gastrointestinal tract from the time of ingestion until it is completely digested and the waste prepared for elimination.
TRUE
Ionic iron is actively transported into the mucosal cells, where it binds to the protein ferritin, a phenomenon called the mucosal iron barrier.
TRUE
Kupffer cells are found in the liver and are responsible for removing bacteria and worn-out cells.
TRUE
Most nutrients are absorbed through the mucosa of the intestinal villi by active transport.
TRUE
Mumps is an inflammation of the parotid glands caused by myxovirus.
TRUE
Peyer's patches are found in the submucosa of the distal end of the small intestine.
TRUE
Some of the microbes that often invade other organs of the body are rarely found in the stomach. The reason for this is the presence of HCl
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
The digestive function of the liver is to produce bile
TRUE
The first teeth to appear are the deciduous teeth.
TRUE
The intrinsic ability of visceral smooth muscle to exhibit the stress-relaxation response is termed plasticity
TRUE
The main chemical activity of the stomach is to begin the digestion of proteins.
TRUE
The major role of absorption in the ileum is to reclaim bile salts to be recycled back to the liver.
TRUE
The major stimulus for production of intestinal fluid is distention or irritation of the intestinal mucosa by hypertonic or acidic chyme
TRUE
The myenteric nerve plexus provides the major nerve supply to the GI tract wall and controls GI motility.
TRUE
The pancreas has both an endocrine and an exocrine function.
TRUE
The peritoneum is the most extensive serous membrane in the body
TRUE
Assume you have been chewing a piece of bread for 5 or 6 minutes. How would you expect its taste to change during this time? Why?
The bread will begin to taste sweet as some of the starch is broken down into sugar due to the chemical digestion of carbohydrates by salivary amylase.
A baby is admitted to the hospital with a history of projectile vomiting after each feeding. On examination, it is found that the sphincter controlling food passage from the stomach to the duodenum is thickened and does not open readily. Because of the baby's loss of gastric juice, his blood probably indicates ________
alkalosis
You have just eaten a meal high in complex carbohydrates. Which of the following enzymes will help to digest the meal?
amylase
Name the three pairs of major salivary glands. Describe their relative locations and their microscopic differences.
The parotid glands lie anterior to the ears between the masseter muscle and the skin. They open into the vestibule next to the second molars of the upper jaw. The submandibular glands lie along the medial aspect of the mandibular body. Their ducts run beneath the mucosa of the oral cavity floor and open at the base of the lingual frenulum. The small sublingual glands lie anterior to the submandibular glands under the tongue. They open via many ducts into the floor of the mouth. Parotid glands contain only serous cells; submandibular glands have equal numbers of serous and mucous cells; and sublingual glands are mostly mucous cells.
Identify three ways the small intestine is modified to increase the surface area for digestion and absorption.
The plicae circulares, villi, and microvilli are modifications of the small intestine for digestion and absorption. The plicae circulares are circular folds of the mucosa and submucosa. They force chyme to move spirally through the lumen. The villi are fingerlike projections of the mucosa. They increase the absorptive surface area. Microvilli are projections of the plasma membrane of the absorptive cells of the mucosa that bear intestinal digestive enzymes. They also increase surface area and enhance absorption.
Chief cells ________
are found in the basal regions of the gastric glands
here are three phases of gastric secretion. The cephalic phase occurs ________.
before food enters the stomach and is triggered by aroma, sight, or thought
Increases surface area for absorption via villi and microvilli.
small. intestines
Select the statement that is true concerning primary teeth.
There are 20 primary teeth, and by 24 months of age most children have all 20.
Which of the following is true concerning the number and type of permanent teeth?
There are 32 permanent teeth, and the wisdom teeth are the last to emerge
________ peritoneum covers the external surfaces of most digestive organs
Visceral
Define constipation and diarrhea. Note possible causes of each.
Watery stools are called diarrhea. Constipation is a condition in which too much water has been absorbed and the stool becomes hard and difficult to pass. Any condition (such as irritation of the colon by bacteria) that rushes food residue through the large intestine before that organ has had sufficient time to absorb the remaining water is known as diarrhea. Constipation may ensue from the lack of fiber in the diet, improper bowel habits, laxative abuse, or anything that decreases motility.
How is salivation controlled
When we ingest food, chemoreceptors and pressoreceptors in the mouth send signals to the salivatory nuclei in the brain stem. The parasympathetic nervous system activity increases and motor fibers trigger the increase in serous, enzyme-rich saliva.
The portal triad contains ________.
a branch of the hepatic artery, a branch of the hepatic portal vein, and a bile duct
Bacteria process undigested chyme from the small intestine
large. intestine
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?
lipase
Digestion of which of the following would be affected the most if the liver were severely damaged
lipids
Main function is to filter and process the nutrient-rich blood delivered to it.
liver
Receives blood via the hepatic portal system
liver
The ________ contains lobules with sinusoids (lined with macrophages) that lead to a central venous structure.
liver
The lamina propria is composed of ________.
loose connective tissue
The sheets of peritoneal membrane that hold the digestive tract in place are called ________.
mesenteries
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
Which of these is not a component of saliva?
nitric oxide
Produces enzymes that break down all categories of foodstuffs.
pancreas
Hydrochloric acid is secreted by which of the secretory cells of the stomach?
parietal cells
Which of the following produce intrinsic factor?
parietal cells
The ________ ligament anchors a tooth in the alveolus of the jaw.
periodontal
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?
plicae circulares and intestinal villi
Hepatocytes do not ________
produce digestive enzymes
Gastrin is a digestive hormone that is responsible for the stimulation of acid secretions in the stomach. These secretions are stimulated by the presence of ________.
protein and peptide fragments
Which of the following is not a factor that helps create the stomach mucosal barrier?
rennin
Important peritoneal folds do not include the ________
round ligament
Paneth cells ________
secrete enzymes that kill bacteria
ormones or paracrines that inhibit gastric secretion include _______
secretin
If an incision has to be made in the small intestine to remove an obstruction, the first layer of tissue to be cut is the ________.
serosa
The salivary glands are composed of which two types of secretory cells?
serous cells and mucous cells
Contains the brush border enzymes that complete digestion of carbohydrates and proteins
small intestine
