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Questions and Answers
What is the primary function of the small intestine in the digestive system?
What is the primary function of the small intestine in the digestive system?
Which of the following organs is NOT an accessory organ of the digestive system associated with the small intestine?
Which of the following organs is NOT an accessory organ of the digestive system associated with the small intestine?
What is the term for the finger-like projections that increase the absorptive surface area of the small intestine?
What is the term for the finger-like projections that increase the absorptive surface area of the small intestine?
What is the main factor that regulates secretions in the small intestine?
What is the main factor that regulates secretions in the small intestine?
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What is the name of the hormone secreted by endocrine cells in the small intestine that stimulates the release of bile from the gallbladder?
What is the name of the hormone secreted by endocrine cells in the small intestine that stimulates the release of bile from the gallbladder?
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What is the approximate width of the small intestine?
What is the approximate width of the small intestine?
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Which of the following is NOT a part of the small intestine?
Which of the following is NOT a part of the small intestine?
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What is the approximate length of the small intestine?
What is the approximate length of the small intestine?
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Study Notes
Structure and Function of the Small Intestine
- The small intestine extends from the pyloric sphincter to the ileocecal valve, where it empties into the large intestine.
- It is the part of the gastrointestinal tract where the majority of digestion and absorption of food takes place.
- The small intestine finishes the process of digestion, absorbs the nutrients, and passes the residue on to the large intestine.
Associated Organs
- The liver, gallbladder, and pancreas are accessory organs of the digestive system that are closely associated with the small intestine.
Divisions of the Small Intestine
- The small intestine is divided into three parts: the duodenum, jejunum, and ileum.
Wall Structure
- The wall of the small intestine has a mucosa with simple columnar epithelium, submucosa, smooth muscle with inner circular and outer longitudinal layers, and serosa.
Absorptive Surface Area
- The absorptive surface area of the small intestine is increased by plicae circulares, villi, and microvilli.
Cell Types and Secretions
- Exocrine cells in the mucosa of the small intestine secrete mucus, peptidase, sucrase, maltase, lactase, lipase, and enterokinase.
- Endocrine cells secrete cholecystokinin and secretin.
Regulation of Secretions
- The presence of chyme is the most important factor for regulating secretions in the small intestine.
- This is a local reflex action in response to chemical and mechanical irritation from the chyme and in response to distention of the intestinal wall.
Dimensions
- The small intestine is approximately 2.5cm wide and 6m long.
- It fills most of the abdomen.
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Description
Learn about the small intestine's location, function, and role in digestion and absorption of nutrients. Understand its anatomy and importance in the gastrointestinal tract.
