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Questions and Answers
Which substances stimulate acid secretion in the stomach?
Which substances stimulate acid secretion in the stomach?
Which phase of acid secretion occurs during eating?
Which phase of acid secretion occurs during eating?
What role does bile play in digestion?
What role does bile play in digestion?
What vessel primarily supplies blood to the small intestine?
What vessel primarily supplies blood to the small intestine?
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Where in the intestinal tract does the absorption of vitamin B12 primarily occur?
Where in the intestinal tract does the absorption of vitamin B12 primarily occur?
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What is the function of the sphincter of Oddi?
What is the function of the sphincter of Oddi?
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Which of the following is NOT a function of the small intestine?
Which of the following is NOT a function of the small intestine?
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Which structure prevents backflow from the large intestine to the small intestine?
Which structure prevents backflow from the large intestine to the small intestine?
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What are the primary functions of the gastrointestinal tract?
What are the primary functions of the gastrointestinal tract?
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Which layer is NOT part of the gastrointestinal tract walls?
Which layer is NOT part of the gastrointestinal tract walls?
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What is the role of the lower esophageal sphincter?
What is the role of the lower esophageal sphincter?
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Where does digestion first begin in the gastrointestinal tract?
Where does digestion first begin in the gastrointestinal tract?
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What type of muscle is found in the upper part of the esophagus?
What type of muscle is found in the upper part of the esophagus?
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Which hormone is involved in delaying gastric emptying?
Which hormone is involved in delaying gastric emptying?
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What substance do chief cells in the stomach secrete?
What substance do chief cells in the stomach secrete?
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Which of the following is NOT a part of the nerve control of the gastrointestinal tract functions?
Which of the following is NOT a part of the nerve control of the gastrointestinal tract functions?
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What role does cholecystokinin play in the digestive process?
What role does cholecystokinin play in the digestive process?
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What enzymes does the exocrine pancreas secrete for digestion?
What enzymes does the exocrine pancreas secrete for digestion?
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Which of the following is a significant indicator of pancreatic dysfunction?
Which of the following is a significant indicator of pancreatic dysfunction?
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How does aging affect the gastrointestinal system?
How does aging affect the gastrointestinal system?
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What stimulates the pancreas to secrete alkaline fluid?
What stimulates the pancreas to secrete alkaline fluid?
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What diagnostic tests are used to evaluate liver function?
What diagnostic tests are used to evaluate liver function?
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What effect does aging have on gastric digestions and emptying?
What effect does aging have on gastric digestions and emptying?
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Which test would likely indicate an obstructive disease of the gallbladder?
Which test would likely indicate an obstructive disease of the gallbladder?
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What is the primary function of the hepatic portal vein?
What is the primary function of the hepatic portal vein?
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Which process describes the recycling of bile acids and salts back to the liver?
Which process describes the recycling of bile acids and salts back to the liver?
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Which statement about bilirubin is correct?
Which statement about bilirubin is correct?
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What substance is synthesized by hepatocytes from cholesterol?
What substance is synthesized by hepatocytes from cholesterol?
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Which of the following proteins is NOT synthesized by the liver?
Which of the following proteins is NOT synthesized by the liver?
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What are the major components of fat synthesized by the liver?
What are the major components of fat synthesized by the liver?
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What role do Kupffer cells play in the liver?
What role do Kupffer cells play in the liver?
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What is the primary storage form of glucose in the liver?
What is the primary storage form of glucose in the liver?
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What role do the villi play in fat absorption in the intestines?
What role do the villi play in fat absorption in the intestines?
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Which type of reflex is triggered by distention of the ileum?
Which type of reflex is triggered by distention of the ileum?
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What are haustra in the context of the large intestine?
What are haustra in the context of the large intestine?
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Which part of the large intestine does NOT include haustra?
Which part of the large intestine does NOT include haustra?
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What occurs during defecation?
What occurs during defecation?
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Which statement accurately describes the liver's functions?
Which statement accurately describes the liver's functions?
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What triggers the intestinointestinal reflex?
What triggers the intestinointestinal reflex?
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Which of the following correctly describes the composition of the intestinal bacteria in the colon?
Which of the following correctly describes the composition of the intestinal bacteria in the colon?
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Study Notes
Gastrointestinal Tract Functions
- The gastrointestinal tract breaks down food mechanically and chemically, absorbing digested nutrients.
- It's a hollow tube from mouth to anus.
- Layers include mucosa, muscularis mucosa, submucosa, muscularis, and serosa (or adventitia).
- Functions (besides swallowing and defecation) are controlled by autonomic nerves (vagus, sympathetic, splanchnic) and intrinsic enteric nerves and hormones.
Digestion Begins in the Mouth
- Digestion starts with chewing and saliva containing amylase, which digests carbohydrates.
Esophagus
- Transports food from mouth to stomach.
- Upper part has striated muscle; lower part has smooth muscle.
- Controlled by a swallowing center in the brainstem.
Two Phases of Swallowing
- Oropharyngeal (voluntary)
- Esophageal (involuntary)
Food Propulsion
- Peristalsis: sequential muscular contractions move food through the tract.
- Lower esophageal sphincter controls movement into the stomach, preventing regurgitation.
Stomach
- Bag-like structure storing and mixing food, producing digestive juices.
- Smooth muscle layers (longitudinal, circular, oblique) mix and propel food.
- Vagus nerve stimulates gastric secretion and motility, while gastrin and motilin stimulate emptying; secretin and cholecystokinin slow emptying.
- Gastric glands produce intrinsic factor (for vitamin B12 absorption) and hydrochloric acid (dissolving fibers, killing microbes, activating pepsin).
- Chief cells secrete pepsinogen, converted to pepsin by acid.
- Acid secretion is stimulated by vagus nerve, gastrin, histamine, and inhibited by sympathetic stimulation and cholecystokinin. Acetylcholine stimulates pepsin secretion.
Small Intestine
- 5 meters long, with three sections: duodenum, jejunum, and ileum.
- Digestion and absorption of most nutrients and water occur here.
- Bile from liver and enzymes from pancreas aid digestion.
- Bile is produced by the liver, essential for fat digestion and absorption, and has alkaline properties to neutralize chyme for optimal enzyme action.
- Enzymes (maltase, sucrase, lactase, proteases, amylase, lipase) digest various food groups.
- Digested products are absorbed into the blood via the hepatic portal vein for further processing.
- Villi increase surface area for absorption.
Large Intestine
- Three bands of longitudinal muscle (teniae coli) form pouches (haustra), aiding in mass movements of feces.
- Absorbs water and electrolytes.
- Stores and eliminates feces.
Accessory Digestive Organs
-
Liver: Largest organ, involved in digestion, metabolism, blood composition, and immune functions.
- Produces bile to aid fat digestion, stored in the gallbladder.
- Hepatocytes are the functional cells of the liver; they produce bile, process blood, and synthesise various substances in the body.
- Gallbladder: Stores and concentrates bile.
-
Pancreas: Endocrine and exocrine functions
- Endocrine: produces hormones (insulin and glucagon) regulating blood sugar.
- Exocrine: secretes enzymes and alkaline fluid assisting in digestion of food.
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Description
This quiz explores the functions and structure of the gastrointestinal tract, including the processes of digestion from the mouth to the esophagus. It covers the mechanics of food propulsion and the roles of various muscles and nerves involved in swallowing. Assess your understanding of how food is processed in the body.
