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Questions and Answers
What type of saliva is produced as a result of sympathetic stimulation?
What type of saliva is produced as a result of sympathetic stimulation?
Which cells in the gastric glands are responsible for producing intrinsic factors necessary for B12 absorption?
Which cells in the gastric glands are responsible for producing intrinsic factors necessary for B12 absorption?
What function does hydrochloric acid (HCl) serve in the stomach?
What function does hydrochloric acid (HCl) serve in the stomach?
During which phase does the stomach prepare to receive food triggered by the thought or smell of food?
During which phase does the stomach prepare to receive food triggered by the thought or smell of food?
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What stimulates the release of gastrin during the gastric phase?
What stimulates the release of gastrin during the gastric phase?
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What is the primary role of chief cells in the gastric glands?
What is the primary role of chief cells in the gastric glands?
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What type of epithelium lines the stomach?
What type of epithelium lines the stomach?
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Which hormone is produced by G cells and stimulates secretion by parietal and chief cells?
Which hormone is produced by G cells and stimulates secretion by parietal and chief cells?
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What is the primary function of the ileum in the small intestine?
What is the primary function of the ileum in the small intestine?
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What enables the small intestine to increase its surface area for absorption?
What enables the small intestine to increase its surface area for absorption?
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Which cells in the intestinal mucosa secrete mucus?
Which cells in the intestinal mucosa secrete mucus?
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During which phase is the release of small intestine secretions stimulated before food arrives?
During which phase is the release of small intestine secretions stimulated before food arrives?
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What types of enzymes are mostly produced in the small intestine?
What types of enzymes are mostly produced in the small intestine?
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What is the main secretion produced by the duodenal glands in the small intestine?
What is the main secretion produced by the duodenal glands in the small intestine?
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Which hormone is secreted by S cells in the intestinal crypts?
Which hormone is secreted by S cells in the intestinal crypts?
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What is the role of the sphincter of Oddi?
What is the role of the sphincter of Oddi?
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Which part of the small intestine is primarily involved in more digestion than absorption?
Which part of the small intestine is primarily involved in more digestion than absorption?
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What role does water play in intestinal secretion?
What role does water play in intestinal secretion?
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Which process involves the physical breakdown of food into smaller pieces?
Which process involves the physical breakdown of food into smaller pieces?
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What role does saliva play in the digestive process?
What role does saliva play in the digestive process?
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What is the primary function of the cephalic phase in digestion?
What is the primary function of the cephalic phase in digestion?
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Which component of saliva specifically helps in lubricating food?
Which component of saliva specifically helps in lubricating food?
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Which structure is not part of the alimentary canal?
Which structure is not part of the alimentary canal?
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What initiates the release of saliva?
What initiates the release of saliva?
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What is the primary function of the excretion process in digestion?
What is the primary function of the excretion process in digestion?
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Which type of digestion occurs at a molecular level using enzymes?
Which type of digestion occurs at a molecular level using enzymes?
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What stimulates the release of pepsinogen from chief cells?
What stimulates the release of pepsinogen from chief cells?
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What is the primary effect of gastrin?
What is the primary effect of gastrin?
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What effect does a drop in pH below 2 have on gastrin release?
What effect does a drop in pH below 2 have on gastrin release?
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Which of the following hormones is released from the small intestine when the pH of chyme is less than 3?
Which of the following hormones is released from the small intestine when the pH of chyme is less than 3?
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What primarily regulates gastric emptying?
What primarily regulates gastric emptying?
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What is a consequence of the stretch in the small intestine?
What is a consequence of the stretch in the small intestine?
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Which region of the small intestine is primarily involved in digestion and absorption?
Which region of the small intestine is primarily involved in digestion and absorption?
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What is the main function of gastrin released from the small intestine when the pH of chyme is 3 or above?
What is the main function of gastrin released from the small intestine when the pH of chyme is 3 or above?
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What is the primary role of the large intestine regarding vitamin absorption?
What is the primary role of the large intestine regarding vitamin absorption?
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What is the process by which carbohydrates are broken down into absorbable monomers called?
What is the process by which carbohydrates are broken down into absorbable monomers called?
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Which of the following sugars is considered a monosaccharide?
Which of the following sugars is considered a monosaccharide?
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Which enzyme is responsible for breaking down starches into smaller pieces in the small intestine?
Which enzyme is responsible for breaking down starches into smaller pieces in the small intestine?
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What component is essential for fats, polysaccharides, and proteins to enter the citric acid cycle?
What component is essential for fats, polysaccharides, and proteins to enter the citric acid cycle?
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What is cellulose classified as in the human diet?
What is cellulose classified as in the human diet?
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Which vitamin is synthesized by bacteria in the large intestine and is necessary for blood clotting?
Which vitamin is synthesized by bacteria in the large intestine and is necessary for blood clotting?
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Which enzyme is found on the brush border of the small intestine and acts on small glucose polymers?
Which enzyme is found on the brush border of the small intestine and acts on small glucose polymers?
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What is the primary function of maltase found on the brush border of the small intestine?
What is the primary function of maltase found on the brush border of the small intestine?
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Which method of carbohydrate absorption does NOT involve sodium?
Which method of carbohydrate absorption does NOT involve sodium?
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Pepsin is primarily active in which location and under what conditions?
Pepsin is primarily active in which location and under what conditions?
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What is the role of bile salts in lipid digestion?
What is the role of bile salts in lipid digestion?
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Which of the following describes the process of amino acid absorption?
Which of the following describes the process of amino acid absorption?
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What occurs to fatty acids and monoglycerides once they enter the intestinal cells?
What occurs to fatty acids and monoglycerides once they enter the intestinal cells?
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What happens to chylomicrons after they are formed in the intestinal cells?
What happens to chylomicrons after they are formed in the intestinal cells?
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Which enzyme is primarily responsible for breaking down polypeptides in the small intestine?
Which enzyme is primarily responsible for breaking down polypeptides in the small intestine?
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What form do lipoproteins take after triglycerides are combined with phospholipids and cholesterol?
What form do lipoproteins take after triglycerides are combined with phospholipids and cholesterol?
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Which type of amino acids has specific sodium-dependent transporters?
Which type of amino acids has specific sodium-dependent transporters?
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Study Notes
Digestive System Overview
- The digestive system breaks down nutrients into absorbable forms for cell use
- It involves ingestion, propulsion (swallowing, peristalsis), mechanical/chemical digestion, secretion, absorption, and excretion
- The alimentary canal (GI tract) is the main pathway (mouth, pharynx, esophagus, stomach, small intestine, large intestine)
- Accessory organs aid digestion (teeth, tongue, gallbladder, salivary glands, liver, pancreas)
Oral Cavity (Mouth)
- Processes: Analysis of materials, mastication (chewing), lubrication (mixing with saliva), limited digestion (saliva)
- Saliva: Mostly water, also contains amylase (breaks down polysaccharides), lipase (breaks down triglycerides), lysozyme (kills bacteria), IgA antibodies (block infections), and mucin (lubricates)
- Saliva Release: Controlled by autonomic nervous system (ANS), stimulated by sight, smell, or thought of food
Stomach
- Histology: Lined with simple columnar epithelium, gastric pits with gastric glands (mucous neck cells, parietal cells, chief cells, enteroendocrine cells)
- Parietal Cells: Produce HCl, which activates enzymes, kills microbes, denatures proteins, and releases iron for absorption
- Chief Cells: Produce pepsinogen (activated to pepsin by HCl), digests proteins to short peptide chains
- Enteroendocrine Cells: Produce hormones such as gastrin, which stimulates HCl and pepsinogen release.
- Stomach Functions: Food storage, mechanical breakdown, some limited protein & fat digestion, and sterilization of food due to acidity
Regulation of Gastric Secretion
- Cephalic Phase: Stimulated by sight, smell, thought of food via the vagus nerve
- Gastric Phase: Stimulated by distention, peptides, and low pH, involves hormonal and neural mechanisms, and slows gastric emptying by stretching the small intestine
- Intestinal Phase: Starts when acidic chyme enters the SI, stimulated by distention and hormones (secretin, CCK, GIP), this inhibits gastric secretions and motility.
Small Intestine
- Structure: Duodenum, jejunum, ileum, increasing surface area with villi, microvilli, and plica circulares to facilitate absorption
- Enzyme Production: Pancreas produces enzymes for carbs, proteins, and lipids; bile from the liver and gallbladder emulsifies fats
- Absorption: Most digestion and absorption in SI occur due to brush border enzymes, and active transport. Cells absorb the monomers.
Large Intestine
- Functions: Fermentation of some indigestible carbohydrates (bacteria produce gases like methane, hydrogen sulfide), absorption of water and electrolytes, and formation/elimination of feces
- Chemical Digestion: Major process is fermentation of indigestible carbohydrates by bacteria
Liver & Gallbladder
- Liver Functions: Carbohydrate, lipid, and amino acid metabolism, waste removal, detoxification, vitamin and mineral storage, plasma protein synthesis, phagocytosis
- Bile Production: Liver produces bile, stored in the gallbladder, important for fat emulsification and absorption
- Regulation: Some hormones regulate the release of bile and pancreatic enzymes in response to chyme in the SI
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Description
Test your knowledge on the digestive system, including the processes involved in digestion and the structure of the alimentary canal. This quiz covers the roles of the oral cavity, stomach, and accessory organs in breaking down nutrients for absorption. Challenge yourself to see how well you understand these fundamental biological concepts!
