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Questions and Answers
What is the main function of the outer longitudinal layers of muscle in the digestive tract?
What is the main function of the outer longitudinal layers of muscle in the digestive tract?
Which structure covers the muscularis externa in most portions of the digestive tract?
Which structure covers the muscularis externa in most portions of the digestive tract?
What major digestive function occurs in the oral cavity?
What major digestive function occurs in the oral cavity?
Which organ processes blood leaving the absorptive surfaces of the digestive tract?
Which organ processes blood leaving the absorptive surfaces of the digestive tract?
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What general category does the function of converting ammonia to urea fall under in the liver?
What general category does the function of converting ammonia to urea fall under in the liver?
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Which of the following is NOT considered an accessory digestive organ?
Which of the following is NOT considered an accessory digestive organ?
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What initiates carbohydrate digestion in the oral cavity?
What initiates carbohydrate digestion in the oral cavity?
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Which vitamin is absorbed and broken down by the liver?
Which vitamin is absorbed and broken down by the liver?
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What is the function of bicarbonate secreted by the pancreas in the small intestine?
What is the function of bicarbonate secreted by the pancreas in the small intestine?
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Which segment of the small intestine is primarily responsible for the most nutrient absorption?
Which segment of the small intestine is primarily responsible for the most nutrient absorption?
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What distinguishes the colon from the small intestine?
What distinguishes the colon from the small intestine?
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What is the primary role of bile salts in digestion?
What is the primary role of bile salts in digestion?
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Which of the following is NOT a function of the large intestine?
Which of the following is NOT a function of the large intestine?
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What happens to bile while it is stored in the gall bladder?
What happens to bile while it is stored in the gall bladder?
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Where does the small intestine begin and end?
Where does the small intestine begin and end?
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Which cells in the stomach secrete hydrochloric acid?
Which cells in the stomach secrete hydrochloric acid?
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Which part of the large intestine serves as the first section that receives chyme from the ileum?
Which part of the large intestine serves as the first section that receives chyme from the ileum?
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What is the pH range of the gastric acid produced in the stomach?
What is the pH range of the gastric acid produced in the stomach?
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Which vitamins are produced by bacteria in the large intestine?
Which vitamins are produced by bacteria in the large intestine?
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Which enzyme is activated by hydrochloric acid in the stomach?
Which enzyme is activated by hydrochloric acid in the stomach?
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What is the primary role of the rectum in the digestive system?
What is the primary role of the rectum in the digestive system?
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What role does the pancreas serve in digestion?
What role does the pancreas serve in digestion?
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What neutralizes the hydrochloric acid that enters the duodenum?
What neutralizes the hydrochloric acid that enters the duodenum?
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Which of the following indicates that a protease is inactive?
Which of the following indicates that a protease is inactive?
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What is the primary role of glucagon in the body?
What is the primary role of glucagon in the body?
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What is produced as a byproduct of protein catabolism?
What is produced as a byproduct of protein catabolism?
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Which hormone is released in response to stress and increases blood glucose levels?
Which hormone is released in response to stress and increases blood glucose levels?
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What is the process of forming peptide bonds between amino acids called?
What is the process of forming peptide bonds between amino acids called?
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What do metabolic intermediates from amino acid processing contribute to?
What do metabolic intermediates from amino acid processing contribute to?
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Which of the following is NOT a function of the thyroid hormone?
Which of the following is NOT a function of the thyroid hormone?
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Under what condition does the body primarily break down muscle protein?
Under what condition does the body primarily break down muscle protein?
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What role do ribosomes play in proteogenesis?
What role do ribosomes play in proteogenesis?
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What is the primary function of mastication in the digestive process?
What is the primary function of mastication in the digestive process?
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What role does the tongue play during mastication?
What role does the tongue play during mastication?
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What is the term for the contractions that move food through the digestive tract?
What is the term for the contractions that move food through the digestive tract?
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Once food enters the small intestine, what is it transformed into?
Once food enters the small intestine, what is it transformed into?
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What is the function of the pyloric sphincter during digestion?
What is the function of the pyloric sphincter during digestion?
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What initiates the process of chemical digestion in the mouth?
What initiates the process of chemical digestion in the mouth?
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Which part of the digestive system is primarily responsible for mixing and churning of the bolus?
Which part of the digestive system is primarily responsible for mixing and churning of the bolus?
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What is the effect of the arrival of food in the stomach?
What is the effect of the arrival of food in the stomach?
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What initiates fat digestion in the mouth?
What initiates fat digestion in the mouth?
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Which enzyme is primarily responsible for fat digestion in the small intestine?
Which enzyme is primarily responsible for fat digestion in the small intestine?
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What is the primary role of bile in fat digestion?
What is the primary role of bile in fat digestion?
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At what pH range is pancreatic lipase most effective?
At what pH range is pancreatic lipase most effective?
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Why does lingual lipase have a limited role in fat digestion?
Why does lingual lipase have a limited role in fat digestion?
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Which type of lipase is predominantly active in children?
Which type of lipase is predominantly active in children?
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What happens to lingual lipase when food moves to the stomach?
What happens to lingual lipase when food moves to the stomach?
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What is the primary reason pancreatic lipase is more important than lingual lipase?
What is the primary reason pancreatic lipase is more important than lingual lipase?
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Study Notes
Digestive System Functions
- Ingestion: Food and liquids enter the oral cavity, an active process.
- Secretion: Digestive tract and glandular organs release water, acids, enzymes, buffers, and salts. This aids digestion and absorption, provides a defense against digestive acids/enzymes and mechanical stresses, and protects against swallowed bacteria.
- Mechanical processing: Physical breakdown of food into smaller particles to allow for easier transport and increased surface area for enzyme action.
- Digestion: Chemical breakdown of food into absorbable molecules.
- Absorption: Movement of organic molecules, electrolytes, vitamins, and water across the digestive epithelium into interstitial fluid, then blood or lymph.
- Defecation: Elimination of solid wastes.
Digestive Tract Layers
- Mucosa: Inner lining, composed of epithelium for absorption. Varied epithelium based on locations and stressors. (e.g. stratified squamous in oral cavity, simple columnar in absorption areas).
- Submucosa: Irregular connective tissue, contains blood vessels, lymphatic vessels, and sensory neurons, and glands that secrete buffers and enzymes.
- Muscularis externa: Dominated by smooth muscle. Inner circular muscles aid in agitation and valve formation, outer longitudinal muscles aid in movement.
- Serosa: Covers the muscularis externa in many parts of the digestive tract.
Organs
- Oral cavity: Ingestion, sensory analysis, lubrication, mechanical digestion (chewing), initiation of carbohydrate and lipid digestion.
- Stomach: Distensible organ that connects the esophagus to the duodenum. Temporarily stores ingested food. Contains gastric glands with parietal and chief cells that secrete intrinsic factor and HCl (for B12 absorption and protein breakdown). Chief cells release pepsinogen (converted to pepsin by HCl). Produces alkaline mucus to protect the stomach lining. Mechanical digestion occurs in stomach.
- Pancreas: Both endocrine and exocrine. Endocrine portion releases hormones (insulin, glucagon) into the blood. Exocrine portion releases pancreatic juice into the duodenum (including bicarbonate to neutralize stomach acid, and digestive enzymes: lipase, amylase, protease).
- Small intestine: Divided into duodenum, jejunum, and ileum. Has large surface area for nutrient absorption (circular folds, villi, microvilli). Receives chyme, digestive secretions (pancreatic, liver). Primary site of digestion and nutrient absorption.
- Large intestine: Begins at the end of the ileum, and ends at the anus. Divided into the Cecum, Colon (ascending, transverse, descending, sigmoid), Rectum, and Anal canal. Compacts and stores fecal material, reabsorbs water and electrolytes, produces vitamins, and excretes waste.
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Description
This quiz explores the essential functions of the digestive system, including ingestion, secretion, mechanical processing, digestion, absorption, and defecation. Additionally, it covers the layers of the digestive tract, particularly the mucosa and its varying epithelium types. Test your knowledge on how these processes work together to support bodily functions.
