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Questions and Answers
What is the primary function of the digestive system?
What is the primary function of the digestive system?
Which of the following is NOT part of the alimentary canal?
Which of the following is NOT part of the alimentary canal?
What process involves the rhythmic local constrictions of the small intestine?
What process involves the rhythmic local constrictions of the small intestine?
Which accessory digestive organ is primarily responsible for producing bile?
Which accessory digestive organ is primarily responsible for producing bile?
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During digestion, what are the main steps that break down complex food molecules?
During digestion, what are the main steps that break down complex food molecules?
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What is the process of eliminating indigestible substances from the body called?
What is the process of eliminating indigestible substances from the body called?
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What role do salivary glands play in digestion?
What role do salivary glands play in digestion?
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Which activity is considered a form of propulsion in the digestive system?
Which activity is considered a form of propulsion in the digestive system?
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What is one of the main functions of the tongue in the oral cavity?
What is one of the main functions of the tongue in the oral cavity?
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What is the primary enzyme found in saliva that initiates the breakdown of starch?
What is the primary enzyme found in saliva that initiates the breakdown of starch?
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Which structure is primarily responsible for closing off the nasopharynx during swallowing?
Which structure is primarily responsible for closing off the nasopharynx during swallowing?
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What type of salivary gland is located anterior to the ear and external to the masseter muscle?
What type of salivary gland is located anterior to the ear and external to the masseter muscle?
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Which type of cell in the salivary glands produces watery secretion and enzymes?
Which type of cell in the salivary glands produces watery secretion and enzymes?
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What provides the roughness to the superior surface of the tongue?
What provides the roughness to the superior surface of the tongue?
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What is the primary composition of saliva?
What is the primary composition of saliva?
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What function does saliva NOT perform?
What function does saliva NOT perform?
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What is the primary function of the serous fluid in the peritoneal cavity?
What is the primary function of the serous fluid in the peritoneal cavity?
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Which of the following organs is classified as an intraperitoneal organ?
Which of the following organs is classified as an intraperitoneal organ?
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What is the role of mesentery in the digestive system?
What is the role of mesentery in the digestive system?
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What term describes organs that are located outside the peritoneum?
What term describes organs that are located outside the peritoneum?
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Which layer of the alimentary canal is responsible for secretion and absorption?
Which layer of the alimentary canal is responsible for secretion and absorption?
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What does the enteric nervous system primarily control?
What does the enteric nervous system primarily control?
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Which structure suspends the liver from the diaphragm?
Which structure suspends the liver from the diaphragm?
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What condition results from inflammation of the peritoneum?
What condition results from inflammation of the peritoneum?
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Which layer of the alimentary canal is characterized by a smooth muscle layer responsible for segmentation and peristalsis?
Which layer of the alimentary canal is characterized by a smooth muscle layer responsible for segmentation and peristalsis?
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Which type of reflex is mediated entirely by enteric nerve plexuses?
Which type of reflex is mediated entirely by enteric nerve plexuses?
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What is the outermost layer of the alimentary canal called?
What is the outermost layer of the alimentary canal called?
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Which of the following is NOT a function of neurons in the digestive system?
Which of the following is NOT a function of neurons in the digestive system?
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What effect do sympathetic signals have on digestion?
What effect do sympathetic signals have on digestion?
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Which of the following factors can provoke digestive activity?
Which of the following factors can provoke digestive activity?
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What is the primary cause of dental caries?
What is the primary cause of dental caries?
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What condition results from neglected gingivitis?
What condition results from neglected gingivitis?
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What is the composition of the esophageal mucosa?
What is the composition of the esophageal mucosa?
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How does calculus affect the gums?
How does calculus affect the gums?
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What structure prevents food from entering the esophagus when not swallowing?
What structure prevents food from entering the esophagus when not swallowing?
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What can happen if an impacted tooth is left untreated?
What can happen if an impacted tooth is left untreated?
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Which layer of the esophagus has a mixed muscular composition?
Which layer of the esophagus has a mixed muscular composition?
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What happens during the process of plaque formation on teeth?
What happens during the process of plaque formation on teeth?
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What is the primary digestive function of the liver?
What is the primary digestive function of the liver?
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Which structure stores and concentrates bile?
Which structure stores and concentrates bile?
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What is the function of the liver sinusoids?
What is the function of the liver sinusoids?
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What substance is primarily responsible for giving feces its brown color?
What substance is primarily responsible for giving feces its brown color?
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What is the common result of gallstones obstructing bile flow?
What is the common result of gallstones obstructing bile flow?
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What is the primary role of stellate macrophages in liver sinusoids?
What is the primary role of stellate macrophages in liver sinusoids?
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What type of tissue regenerates faster than hepatocytes in cases of cirrhosis?
What type of tissue regenerates faster than hepatocytes in cases of cirrhosis?
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What percentage of bile salts are typically recycled during enterohepatic circulation?
What percentage of bile salts are typically recycled during enterohepatic circulation?
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What anatomical feature separates the right and left lobes of the liver?
What anatomical feature separates the right and left lobes of the liver?
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Which of the following best describes the composition of bile?
Which of the following best describes the composition of bile?
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What is the primary role of the pharynx and esophagus in digestion?
What is the primary role of the pharynx and esophagus in digestion?
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Which phase of deglutition involves voluntary muscle contraction?
Which phase of deglutition involves voluntary muscle contraction?
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What is the role of hydrochloric acid (HCl) in the stomach?
What is the role of hydrochloric acid (HCl) in the stomach?
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What is the primary function of the rugae in the empty stomach?
What is the primary function of the rugae in the empty stomach?
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What is the function of the gastric mucosal barrier?
What is the function of the gastric mucosal barrier?
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What typically triggers the cough reflex during swallowing?
What typically triggers the cough reflex during swallowing?
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Which cell type in the stomach secretes intrinsic factor?
Which cell type in the stomach secretes intrinsic factor?
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What can cause gastritis in the stomach?
What can cause gastritis in the stomach?
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Which of the following is a potential consequence of a gastric ulcer?
Which of the following is a potential consequence of a gastric ulcer?
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What is the primary reason for the stomach's ability to expand from 50 ml to 4 L?
What is the primary reason for the stomach's ability to expand from 50 ml to 4 L?
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Which stomach region is continuous with the duodenum through the pyloric valve?
Which stomach region is continuous with the duodenum through the pyloric valve?
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How often are surface mucosal cells in the stomach replaced?
How often are surface mucosal cells in the stomach replaced?
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What is one of the essential functions of the stomach related to vitamin B12?
What is one of the essential functions of the stomach related to vitamin B12?
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Which structure anchors the large intestine to the posterior abdominal wall?
Which structure anchors the large intestine to the posterior abdominal wall?
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What is the primary role of gastrin in gastric secretion?
What is the primary role of gastrin in gastric secretion?
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Which factor does NOT stimulate gastric secretion during the gastric phase?
Which factor does NOT stimulate gastric secretion during the gastric phase?
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What mechanism prevents overfilling of the duodenum?
What mechanism prevents overfilling of the duodenum?
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Which component does NOT contribute to the formation of HCl in the stomach?
Which component does NOT contribute to the formation of HCl in the stomach?
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What phase of gastric secretion is primarily initiated by the sight and smell of food?
What phase of gastric secretion is primarily initiated by the sight and smell of food?
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What effect does emotional stress have on gastric secretion?
What effect does emotional stress have on gastric secretion?
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Which hormone released by duodenal enteroendocrine cells inhibits gastric secretion?
Which hormone released by duodenal enteroendocrine cells inhibits gastric secretion?
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During which gastric phase is the majority of gastric juice released?
During which gastric phase is the majority of gastric juice released?
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What is released when the stomach is stimulated by distension?
What is released when the stomach is stimulated by distension?
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Which mechanism primarily initiates the formation of alkaline tide in the blood?
Which mechanism primarily initiates the formation of alkaline tide in the blood?
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What role does the vagus nerve play in gastric secretion?
What role does the vagus nerve play in gastric secretion?
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Which of the following is NOT part of the enterogastric reflex?
Which of the following is NOT part of the enterogastric reflex?
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Which component primarily contributes to gastric mixing through contractile activity?
Which component primarily contributes to gastric mixing through contractile activity?
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What is one common cause of vomiting (emesis)?
What is one common cause of vomiting (emesis)?
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What results from excessive vomiting in terms of blood pH?
What results from excessive vomiting in terms of blood pH?
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Study Notes
Digestive System Functions
- The digestive system takes in food, breaks it down into nutrients, absorbs these nutrients, and eliminates waste.
Digestive System Organs
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Alimentary Canal (GI Tract): A continuous muscular tube from mouth to anus. It digests food, absorbs nutrients, and expels waste. Includes the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus.
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Accessory Digestive Organs: These organs assist in digestion. Teeth, tongue, and gallbladder are accessory organs. Salivary glands, liver, and pancreas are digestive glands that produce secretions aiding in the breakdown of food.
Digestive Processes
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Ingestion: Taking food into the body.
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Propulsion: Moving food through the alimentary canal. This includes:
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Swallowing: The process of moving food from the mouth to the pharynx.
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Peristalsis: Wave-like muscle contractions that propel food along the digestive tract.
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Mechanical Breakdown: Physical processes that break down food. This includes:
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Chewing: Mechanical breakdown in the mouth.
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Mixing food with saliva by the tongue: Movement and mixing of food.
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Churning food in the stomach: Mixing and grinding within the stomach.
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Segmentation: Rhythmic contractions of the small intestine to mix food and digestive juices, increasing absorption efficiency.
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Digestion: Chemical breakdown of complex food molecules into simpler ones with enzymes.
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Absorption: The uptake of digested nutrients, vitamins, minerals, and water into the bloodstream or lymph.
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Defecation: The elimination of indigestible waste from the body.
Digestive System Relationships
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Peritoneum: Serous membranes lining the abdominal cavity have two layers:
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Visceral peritoneum: Covers digestive organs.
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Parietal peritoneum: Lines the body wall.
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Peritoneal cavity: Space between the two layers; contains serous fluid for lubrication.
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Mesenteries: Double layers of peritoneum that connect organs to the body wall. They hold organs in place, provide routes for blood vessels and nerves, and store fat.
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Greater omentum: Drapes over the abdominal organs.
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Lesser omentum: Connects the liver to the stomach.
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Falciform ligament: Suspends the liver.
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Mesentery proper: Connects the small intestine to the posterior abdominal wall.
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Mesocolon: Connects the large intestine to the posterior abdominal wall.
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Intraperitoneal organs: Organs within the peritoneum (stomach, etc.).
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Retroperitoneal organs: Organs behind the peritoneum (most of the pancreas, etc.).
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Peritonitis: Inflammation of the peritoneum (potentially life-threatening).
Histology of the Alimentary Canal
- Four Basic Layers (Tunics): All digestive organs have the same four layers.
- Mucosa: Innermost lining involved in secretion, absorption, and protection. Primarily contains simple columnar epithelium (with stratified squamous in the mouth, esophagus and anus). Also contains lymphoid follicles (MALT).
- Submucosa: Connective tissue layer containing blood and lymphatic vessels, and elastic fibers.
- Muscularis: Smooth muscle layer responsible for mixing and movement (peristalsis and segmentation) with inner circular muscle and outer longitudinal layers. Sphincters are thickened circular areas that act as valves.
- Serosa: Outermost layer (visceral peritoneum) except in the esophagus (adventitia - dense connective tissue). Retroperitoneal organs have both serosa & adventitia.
Enteric Nervous System
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"Gut Brain": The enteric nervous system is the digestive system's own nervous system, consisting of enteric neurons communicating widely.
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Short & Long Reflexes:
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Short reflexes: Mediated entirely by the enteric nervous system; respond to stimuli within the GI tract.
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Long reflexes: Involve the central nervous system (CNS) and autonomic nerves. Affect digestive activity outside or inside the GI tract (Parasympathetic enhances, Sympathetic inhibits).
Control of Digestive Activity
- Digestive activities are triggered by mechanical and chemical stimuli (responding to stretch, osmolarity, pH, and substrate presence).
- Effectors (smooth muscles & glands) initiate reflexes for movement and activation/inhibition of digestive glands.
- Nervous system controls include intrinsic (short reflexes from the gut brain) and extrinsic (long reflexes through the autonomic nervous system).
- Hormones from digestive system organs trigger other cells in the same or different organs to secrete or contract.
Mouth and Associated Organs
- The mouth initiates ingestion, mechanical (chewing), propulsion (swallowing), and digestion.
- Palate: Divided into hard (bone) and soft (muscle) portions; important during swallowing.
- Tongue: Composed of skeletal muscle for repositioning, mixing, creating the food bolus, swallowing, and taste. Its papillae aid in texture recognition and speech.
- Salivary Glands: Produce saliva to cleanse, dissolve food for taste, moisten food for swallowing, and to initiate starch digestion. Contains water, salivary amylase, lysozyme, IgA antibodies, and defensins.
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Description
Explore the intricate workings of the digestive system, including its main functions and key organs. This quiz covers the alimentary canal, accessory organs, and various digestive processes such as ingestion and propulsion. Test your knowledge on how our body processes food and absorbs nutrients.
