Stomach and Small Intestine - MCAT Biological and Biochemical Foundations of Living Systems
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Which important structure(s) line the small intestine and are key for maximizing nutrient absorption?
Which important structure(s) line the small intestine and are key for maximizing nutrient absorption?
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Microvilli surround villa which line the small intestine. These structures greatly increase the surface area (and therefore nutrient absorption capability) of the small intestine.
Microvilli surround villa which line the small intestine. These structures greatly increase the surface area (and therefore nutrient absorption capability) of the small intestine.
Heart burn is experienced when stomach acid and contents enter the esophagus through which sphincter?
Heart burn is experienced when stomach acid and contents enter the esophagus through which sphincter?
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The lower esophageal sphincter separates the esophagus from the stomach. When stomach acid and contents leak through the lower esophageal sphincter, the acid irritates the esophagus and can lead to pain around the area of the heart. The heart is not actually affected.
The lower esophageal sphincter separates the esophagus from the stomach. When stomach acid and contents leak through the lower esophageal sphincter, the acid irritates the esophagus and can lead to pain around the area of the heart. The heart is not actually affected.
At what point in the small intestine are pancreatic secretions and bile mixed with chyme?
At what point in the small intestine are pancreatic secretions and bile mixed with chyme?
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The duodenum is the first part of the small intestine. This is where the acidic chyme from the stomach mixes with pancreatic secretions and bile. The pancreatic secretions and bile contain bicarbonate, which helps to neutralize the acidic chyme.
The duodenum is the first part of the small intestine. This is where the acidic chyme from the stomach mixes with pancreatic secretions and bile. The pancreatic secretions and bile contain bicarbonate, which helps to neutralize the acidic chyme.
What is the order that food moves through the small and large intestines?
What is the order that food moves through the small and large intestines?
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The small intestine is before the large intestine. It consists of the duodenum, followed by the jejunum, then ileum. The large intestine comes directly after the small intestine and constists of the cecum, followed by the colon, then rectum.
The small intestine is before the large intestine. It consists of the duodenum, followed by the jejunum, then ileum. The large intestine comes directly after the small intestine and constists of the cecum, followed by the colon, then rectum.
A patient who complains of acid reflux is given a drug which raises the pH of the stomach. Which macromolecule's digestion will be affected by this drug?
A patient who complains of acid reflux is given a drug which raises the pH of the stomach. Which macromolecule's digestion will be affected by this drug?
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A low pH in the stomach is necessary in order to activate pepsinogen, the zymogen form of pepsin. Pepsin is necessary for breaking down proteins into smaller polypeptides. In a stomach with a higher pH (less acidic), pepsin production will be decreased, and proteins will not be digested as well.
A low pH in the stomach is necessary in order to activate pepsinogen, the zymogen form of pepsin. Pepsin is necessary for breaking down proteins into smaller polypeptides. In a stomach with a higher pH (less acidic), pepsin production will be decreased, and proteins will not be digested as well.
The stomach secretes large quantities of acid (HCl) into its lumen. What protects the epithelial cells that line the stomach from being broken down by the strong acid?
The stomach secretes large quantities of acid (HCl) into its lumen. What protects the epithelial cells that line the stomach from being broken down by the strong acid?
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A layer of mucous forms between the epithelial cells of the stomach and the acid within the stomach. This mucous is secreted by mucous cells lining the stomach. When the mucous layer is broken down, certain complications can take place (e.g. stomach ulcers).
A layer of mucous forms between the epithelial cells of the stomach and the acid within the stomach. This mucous is secreted by mucous cells lining the stomach. When the mucous layer is broken down, certain complications can take place (e.g. stomach ulcers).
Chyme found in the stomach enters the duodenum via which sphincter?
Chyme found in the stomach enters the duodenum via which sphincter?
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The pyloric sphincter is found between the stomach and the duodenum of the small intestine. The other 3 sphincters are found in different parts of the body.
The pyloric sphincter is found between the stomach and the duodenum of the small intestine. The other 3 sphincters are found in different parts of the body.
Which answer choice incorrectly matches the type of digestion with the location in the body?
Which answer choice incorrectly matches the type of digestion with the location in the body?
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Digestion in the mouth involves the mechanical chewing of food and the action of salivary amylase, which breaks down starch. Proteins do not start getting digested until they are in the stomach, where pepsin breaks them down. Fats and carbohydrates are broken down in the small intestne by lipases and other enzymes like lactase.
Digestion in the mouth involves the mechanical chewing of food and the action of salivary amylase, which breaks down starch. Proteins do not start getting digested until they are in the stomach, where pepsin breaks them down. Fats and carbohydrates are broken down in the small intestne by lipases and other enzymes like lactase.
A patient is recovering from a bacterial toxin that has damaged a large majority of the microvilli in their small intestine. Which is the most immediate issue they should be concerned about?
A patient is recovering from a bacterial toxin that has damaged a large majority of the microvilli in their small intestine. Which is the most immediate issue they should be concerned about?
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The patient should be most concerned with nutrient absorption. Microvilli provide additional surface area to the small intestine, allowing for nutrient absorption. If the lining of the intestine were completely smooth, nutrients would pass too quickly through the digestive system. Enzyme secretion is primarily provided by the liver and pancreas.
The patient should be most concerned with nutrient absorption. Microvilli provide additional surface area to the small intestine, allowing for nutrient absorption. If the lining of the intestine were completely smooth, nutrients would pass too quickly through the digestive system. Enzyme secretion is primarily provided by the liver and pancreas.
The majority of enzymatic digestion occurs in which section of the digestive system?
The majority of enzymatic digestion occurs in which section of the digestive system?
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The small intestine is the location of where the majority of enzymatic digestion occurs because enzymes from the pancreas are incorporated into the digestive process at this point. It is important to begin the enzymatic breakdown of food as early as possible to maximize nutrient absorption through the intestinal system.
The large intestine is responsible for water absorption and waste removal. The mouth begins enzymatic digestion with salivary amylase, and the stomach introduces pepsin, but these do not constitute the majority of enzymatic activity in the digestive tract.
The small intestine is the location of where the majority of enzymatic digestion occurs because enzymes from the pancreas are incorporated into the digestive process at this point. It is important to begin the enzymatic breakdown of food as early as possible to maximize nutrient absorption through the intestinal system.
The large intestine is responsible for water absorption and waste removal. The mouth begins enzymatic digestion with salivary amylase, and the stomach introduces pepsin, but these do not constitute the majority of enzymatic activity in the digestive tract.
If person A has less microvilli in his small intestine than person B, this likely means that .
If person A has less microvilli in his small intestine than person B, this likely means that .
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Microvilli increase the surface area in the small intestine, and thus allow a greater amount of absorption of nutrients once digestion occurs. They do not actually participate in digestion, nor are they linked to intestinal cancer.
Microvilli increase the surface area in the small intestine, and thus allow a greater amount of absorption of nutrients once digestion occurs. They do not actually participate in digestion, nor are they linked to intestinal cancer.
Which of the following junctions allows food to enter the stomach from the esophagus?
Which of the following junctions allows food to enter the stomach from the esophagus?
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Food enters the stomach from the esophagus through the cardiac sphincter.
The pyloric sphincter connects the stomach to the duodenum. The ileocecal sphincter connects the ileum to the large intestine, while the internal (anal) sphincter controls the exit of fecal matter from the body. There is also an external anal sphincter, which is under voluntary control, while the internal is involuntary.
Food enters the stomach from the esophagus through the cardiac sphincter.
The pyloric sphincter connects the stomach to the duodenum. The ileocecal sphincter connects the ileum to the large intestine, while the internal (anal) sphincter controls the exit of fecal matter from the body. There is also an external anal sphincter, which is under voluntary control, while the internal is involuntary.
The major site of digestion in the small intestine occurs in the .
The major site of digestion in the small intestine occurs in the .
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The majority of digestion in the small intestine (and the body in general) occurs in the duodenum, the first section of the small intestine, after passing through the stomach. The digestive enzymes secreted by the pancreas enter the digestive tract in the duodenum.
The next two sites, the jejunum and ileum, are sites of absorption. The cecum is part of the large intestine, not the small intestine.
The majority of digestion in the small intestine (and the body in general) occurs in the duodenum, the first section of the small intestine, after passing through the stomach. The digestive enzymes secreted by the pancreas enter the digestive tract in the duodenum.
The next two sites, the jejunum and ileum, are sites of absorption. The cecum is part of the large intestine, not the small intestine.
What peptide hormone, produced by D cells in the antrum of the stomach, inhibits the release of acid from the stomach parietal cells?
What peptide hormone, produced by D cells in the antrum of the stomach, inhibits the release of acid from the stomach parietal cells?
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D cells in the antrum of the stomach are neuroendocrine cells that secrete somatostatin, a neuropeptide that increases stomach pH by decreasing gastric acid secretion from fundal parietal cells. In a negative feedback mechanism, when the stomach pH falls too low, hydrogen ions (H+) will stimulate D cells to secrete somatostatin. This somatostatin blocks histamine release from enterochromaffin-like (ECL) cells in the stomach, preventing the stimulation of parietal cells to release hydrochloric acid.
Histamine is released by ECL cells, stimulating acid secretion from parietal cells. Gastrin is released by G cells, also stimulating acid secretion from parietal cells. Ghrelin is a neurohormone that stimulates hunger.
D cells in the antrum of the stomach are neuroendocrine cells that secrete somatostatin, a neuropeptide that increases stomach pH by decreasing gastric acid secretion from fundal parietal cells. In a negative feedback mechanism, when the stomach pH falls too low, hydrogen ions (H+) will stimulate D cells to secrete somatostatin. This somatostatin blocks histamine release from enterochromaffin-like (ECL) cells in the stomach, preventing the stimulation of parietal cells to release hydrochloric acid.
Histamine is released by ECL cells, stimulating acid secretion from parietal cells. Gastrin is released by G cells, also stimulating acid secretion from parietal cells. Ghrelin is a neurohormone that stimulates hunger.
The low pH of the stomach is important in many digestive processes of macro- and micro-nutrients, including the conversion of zymogens into active enzymes by the high hydrogen ion concentration, and acid-base reactions with many ingested micronutrients such as vitamins and minerals. The absorption of which metal, important especially in red blood cell function, requires reduction in the stomach?
The low pH of the stomach is important in many digestive processes of macro- and micro-nutrients, including the conversion of zymogens into active enzymes by the high hydrogen ion concentration, and acid-base reactions with many ingested micronutrients such as vitamins and minerals. The absorption of which metal, important especially in red blood cell function, requires reduction in the stomach?
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Iron, usually ingested in the Fe3+ form (ferric iron), must be reduced to Fe2+ (ferrous form) in order to be absorbed in the duodenum of the small intestine. The iron undergoes an oxidation-reduction reaction in the stomach, facilitated by the low pH of the stomach lumen.
Iron, usually ingested in the Fe3+ form (ferric iron), must be reduced to Fe2+ (ferrous form) in order to be absorbed in the duodenum of the small intestine. The iron undergoes an oxidation-reduction reaction in the stomach, facilitated by the low pH of the stomach lumen.
Calcium, a metal important in many functions including neuronal action potentials and bone strength, is absorbed in what location in the gastrointestinal system?
Calcium, a metal important in many functions including neuronal action potentials and bone strength, is absorbed in what location in the gastrointestinal system?
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Calcium is absorbed in the jejunum of the small intestine. Iron is absorbed in the duodenum, calcium in the jejunum, and vitamin B12 (complexed with intrinsic factor) is absorbed in the ileum.
Calcium is absorbed in the jejunum of the small intestine. Iron is absorbed in the duodenum, calcium in the jejunum, and vitamin B12 (complexed with intrinsic factor) is absorbed in the ileum.
What characteristic of the small intestine allows for the significant absorption of micro- and macronutrients?
What characteristic of the small intestine allows for the significant absorption of micro- and macronutrients?
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The villi, characteristic of the small intestine, serve to increase the surface area over which nutrients can be absorbed and allow for the appropriate uptake of micro- and macronutrients. While other parts of the gastrointestinal system contains pits and folds that allow for the secretion of digestive enzymes, only the high surface area of the small intestine allows for the necessary uptake of nutrients.
The villi, characteristic of the small intestine, serve to increase the surface area over which nutrients can be absorbed and allow for the appropriate uptake of micro- and macronutrients. While other parts of the gastrointestinal system contains pits and folds that allow for the secretion of digestive enzymes, only the high surface area of the small intestine allows for the necessary uptake of nutrients.
What sphincter leads from the esophagus to the stomach?
What sphincter leads from the esophagus to the stomach?
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The lower esophageal sphincter (LES) allows food to enter the stomach from the lower esophagus. The LES is under autonomic control, meaning that once food enters the esophagus, it is propelled via peristaltic waves towards the stomach through the lower esophageal sphincter. The pyloric sphincter is between the antrum of the stomach and the duodenum of the small intestine, while the ileocolic sphincter is between the ileum and the colon.
The lower esophageal sphincter (LES) allows food to enter the stomach from the lower esophagus. The LES is under autonomic control, meaning that once food enters the esophagus, it is propelled via peristaltic waves towards the stomach through the lower esophageal sphincter. The pyloric sphincter is between the antrum of the stomach and the duodenum of the small intestine, while the ileocolic sphincter is between the ileum and the colon.
Gastric emptying (the passage of stomach contents to the small intestine) is regulated by which sphincter of the gastrointestinal system?
Gastric emptying (the passage of stomach contents to the small intestine) is regulated by which sphincter of the gastrointestinal system?
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The pyloric sphincter, between the antrum of the stomach and the duodenum of the small intestine, regulates the passage of chyme from the stomach to the small intestine. The antrum has rhythmic contractions that force chyme against the pyloric sphincter, allowing approximately five milliliters to flow through every contraction; thus, the pyloric sphincter allows for the gradual but continual digestion of gastric contents.
The upper and lower esophageal sphincters are involved in the process of swallowing, while the ileocolic sphincter joins the small intestine and large intestine.
The pyloric sphincter, between the antrum of the stomach and the duodenum of the small intestine, regulates the passage of chyme from the stomach to the small intestine. The antrum has rhythmic contractions that force chyme against the pyloric sphincter, allowing approximately five milliliters to flow through every contraction; thus, the pyloric sphincter allows for the gradual but continual digestion of gastric contents.
The upper and lower esophageal sphincters are involved in the process of swallowing, while the ileocolic sphincter joins the small intestine and large intestine.
Which of the following is not part of the small intestine?
Which of the following is not part of the small intestine?
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The small intestine is composed of the duodenum, jejunum, and ileum. The duodenum receives chyme from the stomach and continues to breakdown food particles with additional enzymes from the pancreas. The jejunum is responsible for absorbing most micro- and macronutrients, and the ileum is responsible for absorption of bile salts, vitamin B12/IF, and ascorbic acid. The colon is a part of the large intestine and is primarily involved in water reabsorption.
The small intestine is composed of the duodenum, jejunum, and ileum. The duodenum receives chyme from the stomach and continues to breakdown food particles with additional enzymes from the pancreas. The jejunum is responsible for absorbing most micro- and macronutrients, and the ileum is responsible for absorption of bile salts, vitamin B12/IF, and ascorbic acid. The colon is a part of the large intestine and is primarily involved in water reabsorption.