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Questions and Answers
The digestive tract is an internal passageway, which begins at the mouth and ends at the:
The digestive tract is an internal passageway, which begins at the mouth and ends at the:
All of the following are components of the digestive system EXCEPT:
All of the following are components of the digestive system EXCEPT:
Most of the digestive tract is lined by:
Most of the digestive tract is lined by:
There are three pairs of salivary glands, which produce saliva, which contains all of the following EXCEPT:
There are three pairs of salivary glands, which produce saliva, which contains all of the following EXCEPT:
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Chewing (mastication) breaks up large food particles and mixes the food with the secretions of the:
Chewing (mastication) breaks up large food particles and mixes the food with the secretions of the:
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Salivary secretion is under neural control and food in the mouth causes ____________ secretion of saliva.
Salivary secretion is under neural control and food in the mouth causes ____________ secretion of saliva.
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Swallowing is initiated by a voluntary action of collecting oral contents on the tongue and propelling them backwards into the:
Swallowing is initiated by a voluntary action of collecting oral contents on the tongue and propelling them backwards into the:
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A travelling wave of smooth muscle contractions that propels food along the digestive tract is called a:
A travelling wave of smooth muscle contractions that propels food along the digestive tract is called a:
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The entrance to the stomach is guarded by the lower esophageal ______________, which allows food to enter the stomach but prevents gastric reflux of stomach contents.
The entrance to the stomach is guarded by the lower esophageal ______________, which allows food to enter the stomach but prevents gastric reflux of stomach contents.
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Which of the following is NOT a region of the stomach?
Which of the following is NOT a region of the stomach?
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Mucus is secreted by goblet cells, hydrochloric acid (HCl) is secreted by parietal cells, while pepsin is secreted from the ___________________ of the stomach.
Mucus is secreted by goblet cells, hydrochloric acid (HCl) is secreted by parietal cells, while pepsin is secreted from the ___________________ of the stomach.
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A major function of mucus is to protect the lining of the stomach from the digestive actions of:
A major function of mucus is to protect the lining of the stomach from the digestive actions of:
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All of the following are phases of gastric secretion EXCEPT:
All of the following are phases of gastric secretion EXCEPT:
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The pyloric sphincter regulates the release of chyme INTO the:
The pyloric sphincter regulates the release of chyme INTO the:
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The small intestine plays a key role in digestion and absorption of nutrients while the large intestine:
The small intestine plays a key role in digestion and absorption of nutrients while the large intestine:
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In healthy individuals, the small intestine is divided into:
In healthy individuals, the small intestine is divided into:
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The large intestine consists of all of the following except:
The large intestine consists of all of the following except:
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Exocrine pancreatic cells include the acinar cells and epithelial cells, which secrete pancreatic juice into:
Exocrine pancreatic cells include the acinar cells and epithelial cells, which secrete pancreatic juice into:
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Which of the following is NOT a specific pancreatic exocrine enzyme?
Which of the following is NOT a specific pancreatic exocrine enzyme?
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The liver is one of the most versatile organs of the body, which provides essential metabolic and synthetic functions and secretes a fluid called:
The liver is one of the most versatile organs of the body, which provides essential metabolic and synthetic functions and secretes a fluid called:
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Bile salts are involved with __________________, which dramatically increases the surface area of lipid droplets to enhance enzyme attack, and facilitates interaction between the lipids and lipid-digesting enzymes.
Bile salts are involved with __________________, which dramatically increases the surface area of lipid droplets to enhance enzyme attack, and facilitates interaction between the lipids and lipid-digesting enzymes.
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The gallbladder stores and concentrates bile prior to release into the small intestine in response to stimulation by the intestinal hormone:
The gallbladder stores and concentrates bile prior to release into the small intestine in response to stimulation by the intestinal hormone:
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Duodenal enteroendocrine cells help co-ordinate and regulate digestive functions by production of hormones including which of the following:
Duodenal enteroendocrine cells help co-ordinate and regulate digestive functions by production of hormones including which of the following:
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Secretin increases secretions of bile and buffers by the:
Secretin increases secretions of bile and buffers by the:
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Cholecystokinin (CCK) accelerates production and secretion of digestive enzymes and pushes pancreatic secretion and bile into the:
Cholecystokinin (CCK) accelerates production and secretion of digestive enzymes and pushes pancreatic secretion and bile into the:
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Gastric inhibitory polypeptide (GIP) inhibits gastric activity and mainly stimulates:
Gastric inhibitory polypeptide (GIP) inhibits gastric activity and mainly stimulates:
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Vasoactive intestinal peptide (VIP) stimulates the secretion of intestinal glands and inhibits acid production in the:
Vasoactive intestinal peptide (VIP) stimulates the secretion of intestinal glands and inhibits acid production in the:
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Gastrin promotes increased ___________________ motility.
Gastrin promotes increased ___________________ motility.
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Carbohydrate digestion starts in the mouth (salivary amylase) and continues to digest food in the stomach for about ______________ before stomach acids inactivate the enzyme.
Carbohydrate digestion starts in the mouth (salivary amylase) and continues to digest food in the stomach for about ______________ before stomach acids inactivate the enzyme.
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Disaccharides and trisaccharides are broken down into monosaccharides by brush border enzymes of the intestinal microvilli before:
Disaccharides and trisaccharides are broken down into monosaccharides by brush border enzymes of the intestinal microvilli before:
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Which of the following is NOT a disaccharide:
Which of the following is NOT a disaccharide:
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Absorption of monosaccharides is by:
Absorption of monosaccharides is by:
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Lipid digestion involves pancreatic lipase from the pancreas, which transforms triglycerides into free fatty acids and:
Lipid digestion involves pancreatic lipase from the pancreas, which transforms triglycerides into free fatty acids and:
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The fatty acids produced from triglycerides interact with bile salts to form small lipid-bile salt complexes called:
The fatty acids produced from triglycerides interact with bile salts to form small lipid-bile salt complexes called:
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Lipids enter intestinal cells and generate new triglycerides, which associate with steroids, phospholipids and proteins to create _________________, which are secreted into the interstitial fluid.
Lipids enter intestinal cells and generate new triglycerides, which associate with steroids, phospholipids and proteins to create _________________, which are secreted into the interstitial fluid.
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Protein digestion is complex and time-consuming, where stomach acids, pepsin, trypsin and other enzymes break bonds in the protein to degrade it into constituent:
Protein digestion is complex and time-consuming, where stomach acids, pepsin, trypsin and other enzymes break bonds in the protein to degrade it into constituent:
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Amino acids are absorbed by each of the following EXCEPT:
Amino acids are absorbed by each of the following EXCEPT:
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Of the 9 litres of water passing through the intestine, ____________________ are reabsorbed and the remainder is excreted in stool.
Of the 9 litres of water passing through the intestine, ____________________ are reabsorbed and the remainder is excreted in stool.
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Most water-soluble vitamins are absorbed through the action of ________________ into the digestive epithelium in healthy individuals.
Most water-soluble vitamins are absorbed through the action of ________________ into the digestive epithelium in healthy individuals.
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Up to 80% of ingested calcium is absorbed and this process is regulated by the _______________________ derivative and facilitated by protein.
Up to 80% of ingested calcium is absorbed and this process is regulated by the _______________________ derivative and facilitated by protein.
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Study Notes
The Digestive Tract
- The digestive tract is a muscular tube responsible for breaking down food and absorbing nutrients.
- It begins with the mouth and ends at the anus.
- Main components: mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus.
- Accessory organs: salivary glands, liver, pancreas, gallbladder.
Digestive Tract Lining
- The digestive tract is lined with a mucous membrane for protection and secretion.
- This membrane is composed of simple columnar epithelium, which contains specialized cells for absorption and secretion.
Salivary Glands
- There are three pairs of salivary glands: parotid, submandibular, and sublingual.
- Saliva is produced by these glands and contains: water, electrolytes, mucin, and salivary amylase.
- Mucin lubricates food for easier swallowing.
- Salivary amylase begins the digestion of carbohydrates.
Swallowing
- The process of swallowing involves the mouth, pharynx, and esophagus.
- It is initiated voluntarily by collecting food on the tongue and propelling it towards the pharynx.
- After the voluntary stage, the swallowing reflex is triggered, moving food towards the esophagus.
Peristalsis
- This is a wave of smooth muscle contractions that propels food through the digestive tract.
Stomach
- The stomach is a J-shaped organ located in the upper abdomen.
- It has four regions: cardia, fundus, body, and pylorus.
- The lower esophageal sphincter regulates the passage of food into the stomach.
- The stomach churns and mixes food with gastric secretions.
Gastric Secretions
- The stomach secretes gastric juice, which contains hydrochloric acid, pepsin, and mucus.
- Hydrochloric acid activates pepsin, a protein-digesting enzyme.
- Mucus protects the stomach lining.
Phases of Gastric Secretion
- Cephalic phase: stimulated by sight, smell, or thought of food.
- Gastric phase: stimulated by food in the stomach, stretching the stomach walls.
- Intestinal phase: regulated by the small intestine, stimulated by chyme entering the duodenum.
Small Intestine
- The small intestine is the primary site for digestion and absorption of nutrients.
- It is divided into three sections: duodenum, jejunum, and ileum.
- It receives chyme from the stomach, pancreatic juice, and bile.
Large Intestine
- The large intestine absorbs water and electrolytes.
- It consists of the cecum, colon, rectum, and anus.
- The colon is further divided into four sections: ascending colon, transverse colon, descending colon, and sigmoid colon.
Pancreas
- The pancreas is both an endocrine and exocrine gland.
- Exocrine secretions include pancreatic juice, which contains enzymes like lipase, proteolytic enzymes, and amylase.
- These enzymes break down fats, proteins, and carbohydrates, respectively.
Liver
- The liver is a vital organ responsible for many metabolic processes.
- It produces bile, which aids in the digestion of fats.
Bile
- Bile is stored in the gallbladder and released into the small intestine.
- Bile salts emulsify fats, increasing their surface area and making them更容易被消化酶分解。
Hormones that Regulate Digestion
- Cholecystokinin (CCK): Stimulates the release of pancreatic enzymes and bile.
- Secretin: Stimulates the release of pancreatic bicarbonate and bile.
- Gastric inhibitory polypeptide (GIP): Inhibits gastric secretion and stimulates insulin release.
- Vasoactive intestinal peptide (VIP): Stimulates intestinal secretion and relaxes smooth muscle.
- Gastrin: Stimulates gastric acid secretion and motility.
Digestion and Absorption
- Carbohydrate digestion begins in the mouth with salivary amylase and continues in the small intestine with pancreatic amylase.
- Protein digestion begins in the stomach with pepsin and continues in the small intestine with pancreatic proteolytic enzymes.
- Lipid digestion occurs primarily in the small intestine with the aid of pancreatic lipase and bile salts.
- All three macronutrients are broken down into their monomers (monosaccharides, amino acids, fatty acids) for absorption.
- Nutrient absorption occurs primarily in the small intestine.
- Water absorption occurs in both the small and large intestines.
- Vitamin and mineral absorption occurs throughout the digestive tract.
Key Takeaways
- The digestive system is a complex organ system responsible for the breakdown of food and absorption of nutrients.
- It is composed of a muscular tube called the digestive tract and accessory organs, including the salivary glands, pancreas, liver, and gallbladder.
- The process of digestion involves mechanical and chemical breakdown of food.
- Digestive hormones play a crucial role in regulating the digestive process.
- Absorption of nutrients occurs primarily in the small intestine.
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Description
Explore the anatomy and functions of the digestive tract in this quiz. Discover the roles of various organs, salivary glands, and the processes involved in digestion and absorption. Test your knowledge of the entire digestive system from mouth to anus.
