Digestive Physiology - AP Biology
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The high concentration of __________ present in the stomach activates pepsinogen, allowing it to become active pepsin.
The high concentration of __________ present in the stomach activates pepsinogen, allowing it to become active pepsin.
Hydrochloric acid, produced by the parietal cells of the stomach, activates the zymogen pepsinogen.
Hydrochloric acid, produced by the parietal cells of the stomach, activates the zymogen pepsinogen.
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A patient is admitted to the hospital with severe abdominal pain. A scan reveals that the gall bladder has multiple stones in it, and one is blocking the cystic duct.
Which of the following molecules would be inadequately absorbed during gall bladder obstruction?
A patient is admitted to the hospital with severe abdominal pain. A scan reveals that the gall bladder has multiple stones in it, and one is blocking the cystic duct.
Which of the following molecules would be inadequately absorbed during gall bladder obstruction?
The gall bladder is important because of its storage and release of bile during digestion. Bile is important in the emulsification (or breaking up) of nonpolar fats in the aqueous small intestinal fluid. Cystic duct obstruction would result in bile being unable to reach the small intestine, and triglycerides would be unable to be properly emulsified and absorbed.
The gall bladder is important because of its storage and release of bile during digestion. Bile is important in the emulsification (or breaking up) of nonpolar fats in the aqueous small intestinal fluid. Cystic duct obstruction would result in bile being unable to reach the small intestine, and triglycerides would be unable to be properly emulsified and absorbed.
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Where is bile stored when digestion is not occurring?
Where is bile stored when digestion is not occurring?
The liver produces bile, which travels down the bile duct to be released into the small intestine, specifically the duodenum. When the duct is not open, bile backs up and gets stored in the gall bladder. Once the duct is open, when the small intestine senses the presence of food, the gall bladder will release the bile to emulsify fats during digestion.
The liver produces bile, which travels down the bile duct to be released into the small intestine, specifically the duodenum. When the duct is not open, bile backs up and gets stored in the gall bladder. Once the duct is open, when the small intestine senses the presence of food, the gall bladder will release the bile to emulsify fats during digestion.
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Which of the following does NOT play a role in the emulsification of dietary lipids?
Which of the following does NOT play a role in the emulsification of dietary lipids?
Both bile salts and phospholipids are excreted from the bile duct into the upper small intestine (duodenum) to emulsify lipids. They are both amphipathic molecules, which means they have non-polar/lipophilic ends that can bind to lipids and polar/hydrophilic ends that can bind to water, thus emulsifying the lipids that they contact.
As these compounds are excreted from a single duct, small intestine motility allows them to mix with the contents of the small intestine and emulsify more lipids than they would be able to in a still environment. Small intestine motility also helps to break up large globules of dietary fat.
Once emulsified, dietary fat can be broken down by lipase, but lipase itself does not enhance emulsification.
Both bile salts and phospholipids are excreted from the bile duct into the upper small intestine (duodenum) to emulsify lipids. They are both amphipathic molecules, which means they have non-polar/lipophilic ends that can bind to lipids and polar/hydrophilic ends that can bind to water, thus emulsifying the lipids that they contact.
As these compounds are excreted from a single duct, small intestine motility allows them to mix with the contents of the small intestine and emulsify more lipids than they would be able to in a still environment. Small intestine motility also helps to break up large globules of dietary fat.
Once emulsified, dietary fat can be broken down by lipase, but lipase itself does not enhance emulsification.
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Which organ stores the compound responsible for emulsifying lipids during digestion?
Which organ stores the compound responsible for emulsifying lipids during digestion?
Fats are generally composed of nonpolar lipids, making them hydrophobic and insoluble. In order to digest fats, they must be grouped together to increase their surface area and allow for enzyme interaction, digestion, and absorption.
Fat emulsification is the process of increasing the surface area of fats in the small intestine by grouping them into small clusters. This is the responsibility of bile, a liquid created by the liver and stored in the gallbladder. Actual digestion of the fats is then accomplished by lipase, an enzyme from the pancreas. Digested lipids are then transported into the lacteals of the microvilli for transportation through the lymphatic system before entering the blood.
Fats are generally composed of nonpolar lipids, making them hydrophobic and insoluble. In order to digest fats, they must be grouped together to increase their surface area and allow for enzyme interaction, digestion, and absorption.
Fat emulsification is the process of increasing the surface area of fats in the small intestine by grouping them into small clusters. This is the responsibility of bile, a liquid created by the liver and stored in the gallbladder. Actual digestion of the fats is then accomplished by lipase, an enzyme from the pancreas. Digested lipids are then transported into the lacteals of the microvilli for transportation through the lymphatic system before entering the blood.
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Bile is produced in the __________, stored in the __________, and released into the __________.
Bile is produced in the __________, stored in the __________, and released into the __________.
The liver is responsible for synthesizing bile salts; these salts are transferred into the gallbladder as bile. The gallbladder stores bile, which it then secretes into the small intestine. Bile contributes to digestion by breaking up large fat globules, a process known as emulsification. Fats are insoluble in water, so emulsification provides pancreatic lipase with more surface area on which to act.
Neither the spleen nor the large intestine are relevant answers to this sentence. The large intestine helps remove undigested waste from the body, absorbs water from waste, and produces/absorbs vitamins (due to colonies of beneficial bacteria that live in the large intestine). The spleen is an organ responsible for filtering the blood and housing white blood cells; it is not involved in digestion.
The liver is responsible for synthesizing bile salts; these salts are transferred into the gallbladder as bile. The gallbladder stores bile, which it then secretes into the small intestine. Bile contributes to digestion by breaking up large fat globules, a process known as emulsification. Fats are insoluble in water, so emulsification provides pancreatic lipase with more surface area on which to act.
Neither the spleen nor the large intestine are relevant answers to this sentence. The large intestine helps remove undigested waste from the body, absorbs water from waste, and produces/absorbs vitamins (due to colonies of beneficial bacteria that live in the large intestine). The spleen is an organ responsible for filtering the blood and housing white blood cells; it is not involved in digestion.
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Bile salts are amphipathic and essential for fat absorption. Which of the following nutrients will be difficult to absorb in a patient with an inability to secrete bile salts into the stomach?
I. Vitamin A
II. Vitamin B
III. Vitamin C
Bile salts are amphipathic and essential for fat absorption. Which of the following nutrients will be difficult to absorb in a patient with an inability to secrete bile salts into the stomach?
I. Vitamin A
II. Vitamin B
III. Vitamin C
Bile salt emulsifies fat into chylomicrons to allow for absorption. Of the choices, only vitamin A is fat-soluble. Vitamins B and C are both water-soluble.
Bile salt emulsifies fat into chylomicrons to allow for absorption. Of the choices, only vitamin A is fat-soluble. Vitamins B and C are both water-soluble.
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Bile salts emulsify dietary fats by breaking them down into smaller clusters and creating a molecule called a __________.
Bile salts emulsify dietary fats by breaking them down into smaller clusters and creating a molecule called a __________.
Bile salts surround fat droplets in order to create micelles. These micelles are more accessible to the enzymes that have the ability to break them down further. Chylomicrons are lipoproteins that are important in transport and metabolism of lipids.
Bile salts surround fat droplets in order to create micelles. These micelles are more accessible to the enzymes that have the ability to break them down further. Chylomicrons are lipoproteins that are important in transport and metabolism of lipids.
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Bile salts make fat droplets more accessible to the enzyme __________.
Bile salts make fat droplets more accessible to the enzyme __________.
Once large fat clusters are broken down by bile salts to become smaller micelles, pancreatic lipase has more surface area to access fats. The enzymes are able to reach the fat droplet through the gaps between bile salts. Fats are not emulsified by bile yet in the mouth, so lingual lipase acts upstream of bile to hydrolize long chain hydrocarbons. The other answer choices are proteases.
Once large fat clusters are broken down by bile salts to become smaller micelles, pancreatic lipase has more surface area to access fats. The enzymes are able to reach the fat droplet through the gaps between bile salts. Fats are not emulsified by bile yet in the mouth, so lingual lipase acts upstream of bile to hydrolize long chain hydrocarbons. The other answer choices are proteases.
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Which of the following enzymes does NOT directly contribute to protein digestion?
Which of the following enzymes does NOT directly contribute to protein digestion?
Gastrin is secreted in the stomach, and stimulates the secretion of hydrochloric acid by parietal cells. The other three enzymes directly aid in the digestion of proteins. Trypsin and chymotrypsin are released from the pancreas into the duodenum, and pepsin digests proteins located in the stomach. Each of these has different cleavange targets within protein sequences and can be used as a restriction enzyme in experimental procedures.
Gastrin is secreted in the stomach, and stimulates the secretion of hydrochloric acid by parietal cells. The other three enzymes directly aid in the digestion of proteins. Trypsin and chymotrypsin are released from the pancreas into the duodenum, and pepsin digests proteins located in the stomach. Each of these has different cleavange targets within protein sequences and can be used as a restriction enzyme in experimental procedures.
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Ammonia is a byproduct of digestive absorption. It is converted to urea by the liver and expelled in the urine.
Which macromolecule is responsible for the presence of the ammonia byproduct during digestion and absorption?
Ammonia is a byproduct of digestive absorption. It is converted to urea by the liver and expelled in the urine.
Which macromolecule is responsible for the presence of the ammonia byproduct during digestion and absorption?
In order to answer this question, visualize the macromolecules as their monomers. The chemical formula for ammonia is 
, so the monomer will need to include nitrogen. Carbohydrates are chains of monosaccharides and are only composed of carbon, hydrogen, and oxygen. Fatty acids are nonpolar molecules, and are composed of only carbon and hydrogen. Proteins are composed of amino acid monomers. Amino acids have an amino terminus, which includes a nitrogen atom. As a result, only proteins have the nitrogen atom which can be used in the byproduct of ammonia.
In order to answer this question, visualize the macromolecules as their monomers. The chemical formula for ammonia is
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Which of the following functions is NOT accomplished by the liver?
Which of the following functions is NOT accomplished by the liver?
The liver is a very important organ with many interrelated functions, however, the liver is not responsible for the creation of antibodies. This is done by plasma cells, a key cell type in the immune system.
The liver is a very important organ with many interrelated functions, however, the liver is not responsible for the creation of antibodies. This is done by plasma cells, a key cell type in the immune system.
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Which of the following cells in the stomach is necessary for the activation of pepsinogen?
Which of the following cells in the stomach is necessary for the activation of pepsinogen?
Pepsinogen is released by chief cells in the stomach, and is the zymogen form of pepsin. Pepsinogen requires an acidic environment in order to be converted to pepsin. Parietal cells release hydrochloric acid into the stomach lumen, thus activating the enzyme.
G cells and goblet cells secrete gastrin and mucous, respectively, into the stomach.
Pepsinogen is released by chief cells in the stomach, and is the zymogen form of pepsin. Pepsinogen requires an acidic environment in order to be converted to pepsin. Parietal cells release hydrochloric acid into the stomach lumen, thus activating the enzyme.
G cells and goblet cells secrete gastrin and mucous, respectively, into the stomach.
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Which of the following statements about the pancreas is incorrect?
Which of the following statements about the pancreas is incorrect?
Glycogen is stored primarily in cells of the liver and muscles. The pancreas is responsible for secreting hydrolytic enzymes into the small intestine via the pancreatic duct. Along with these digestive enzymes the pancreas releases bicarbonate, which reacts in an acid-base reaction with acidic stomach chyme to pervent it from damaging the intestine. The pancreas also releases insulin and glucagon, among other hormones.
Glycogen is stored primarily in cells of the liver and muscles. The pancreas is responsible for secreting hydrolytic enzymes into the small intestine via the pancreatic duct. Along with these digestive enzymes the pancreas releases bicarbonate, which reacts in an acid-base reaction with acidic stomach chyme to pervent it from damaging the intestine. The pancreas also releases insulin and glucagon, among other hormones.
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Which of the following statements about the hormone secretin is false?
Which of the following statements about the hormone secretin is false?
Secretin is a hormone released by the duodenum in response to an influx of acid. The hormone targets the stomach, to reduce the amount of acid that can pass through to the small intestine, and the pancreas, to increase secretion of bicarbonate, which neutralizes the acidity.
Secretin is a hormone released by the duodenum in response to an influx of acid. The hormone targets the stomach, to reduce the amount of acid that can pass through to the small intestine, and the pancreas, to increase secretion of bicarbonate, which neutralizes the acidity.
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Which of the following statements about cholecystokinin (CCK) and gastrin is true?
Which of the following statements about cholecystokinin (CCK) and gastrin is true?
Cholecystokini (CCK) targets the stomach to inhibit motility, while gastrin targets the stomach to increase motility. Gastrin is secreted by the duodenum and the stomach, but targets only the stomach. CCK, however, targets the stomach, pancreas, and gall bladder.
Cholecystokini (CCK) targets the stomach to inhibit motility, while gastrin targets the stomach to increase motility. Gastrin is secreted by the duodenum and the stomach, but targets only the stomach. CCK, however, targets the stomach, pancreas, and gall bladder.
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Which digestive system organ secretes enzymes vital for lipid digestive, and where are these enzymes introduced into the digestive tract?
Which digestive system organ secretes enzymes vital for lipid digestive, and where are these enzymes introduced into the digestive tract?
Lipase is synthesized and secreted from the pancreas into the duodenum of the small intestine. Lipase plays a key role in the digestion of lipids.
Lipase is synthesized and secreted from the pancreas into the duodenum of the small intestine. Lipase plays a key role in the digestion of lipids.
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Which enzyme operates at the lowest pH?
Which enzyme operates at the lowest pH?
Pepsin is the only enzyme out of the given choices that functions in the stomach, where the pH is very low (acidic). Trypsin, carboxypeptidase, and lipase all function within the small intestine, where the pH is usually more basic to neutralize the pH of chyme as food is digested. Amylase is found in saliva and functions in the mouth, where pH is about neutral.
Pepsin is the only enzyme out of the given choices that functions in the stomach, where the pH is very low (acidic). Trypsin, carboxypeptidase, and lipase all function within the small intestine, where the pH is usually more basic to neutralize the pH of chyme as food is digested. Amylase is found in saliva and functions in the mouth, where pH is about neutral.
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One of the functions of the liver is __________.
One of the functions of the liver is __________.
The liver has a large number of functions, including metabolizing toxins, synthesizing proteins, and storing glucose in the form of glycogen. The only answer choice that describes liver functions is the production of bile, triglycerides, and cholesterol.
The pancreas produces insulin from beta cells, the gall bladder stores bile, and the adrenal medulla secretes epinephrine and norepinephrine. Physical digestion takes place mainly in the mouth and stomach, not the liver.
The liver has a large number of functions, including metabolizing toxins, synthesizing proteins, and storing glucose in the form of glycogen. The only answer choice that describes liver functions is the production of bile, triglycerides, and cholesterol.
The pancreas produces insulin from beta cells, the gall bladder stores bile, and the adrenal medulla secretes epinephrine and norepinephrine. Physical digestion takes place mainly in the mouth and stomach, not the liver.
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What macromolecule is digested first by chemical means?
What macromolecule is digested first by chemical means?
Carbohydrates begin their digestion in the mouth, where salivary amylase is produced.
Fats are emulsified by bile and digested by lipase in the small intestine. Nucleic acids are also digested in the small intestine by nucleases. Proteins begin their digestion in the stomach, where the low pH of gastric juice begins the breakdown process and pepsin begins to cleave peptide bonds. Protein digestion continues in the small intestine with other protease enzymes.
Carbohydrates begin their digestion in the mouth, where salivary amylase is produced.
Fats are emulsified by bile and digested by lipase in the small intestine. Nucleic acids are also digested in the small intestine by nucleases. Proteins begin their digestion in the stomach, where the low pH of gastric juice begins the breakdown process and pepsin begins to cleave peptide bonds. Protein digestion continues in the small intestine with other protease enzymes.
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