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Questions and Answers

What is the function of the sphincter of Oddi in the GI tract?

  • Delivers stored bile to the intestine (correct)
  • Facilitates the movement of food and waste caudally
  • Enhances digestion and absorption of nutrients
  • Coordinates with exocrine secretions of pancreas/liver

    • How long does it take for significant absorption of nutrients to occur in the GI tract, based on the information provided?

  • 1-3 days
  • 12-24 hours
  • 7-10 hours (correct)
  • 1-4 hours

    • Which part of the GI tract mixes and grinds food while it stays in it for 1-4 hours?

  • Small intestine
  • Esophagus
  • Stomach (correct)
  • Mouth

    • What is the purpose of mastication of food in the digestive process?

    <p>Creates bolus that can be swallowed</p> Signup and view all the answers

    Which organ is essential for secreting digestive enzymes in the GI tract?

    <p>Pancreas</p> Signup and view all the answers

    What is the main purpose of the large intestine in the digestive process?

    <p>Transports fluids and electrolytes</p> Signup and view all the answers

    What is the main function of internal and external anal sphincters?

    <p>Maintain positive resting pressure</p> Signup and view all the answers

    Which stimuli induce sphincteric contraction?

    <p>Distal stimuli</p> Signup and view all the answers

    What innervates most muscles of mastication?

    <p>Motor branch of CN V</p> Signup and view all the answers

    What is the purpose of chewing in digestion?

    <p>Act on food particle surface only</p> Signup and view all the answers

    What happens when a bolus of food is in the mouth?

    <p>Jaw drops</p> Signup and view all the answers

    During swallowing, what prevents food from entering the trachea?

    <p>Epiglottis covering the glottis</p> Signup and view all the answers

    What initiates mixing waves in the stomach after food ingestion?

    <p>Antral peristaltic contractions</p> Signup and view all the answers

    What is the function of the pyloric pump in the stomach?

    <p>To force chyme into the duodenum</p> Signup and view all the answers

    When do hunger contractions typically begin post-prandially?

    <p>12-24 hours after eating</p> Signup and view all the answers

    What triggers the receptive relaxation of the stomach?

    <p>Movement of pharynx and esophagus</p> Signup and view all the answers

    Which factor most prominently enhances the activity of the pyloric pump?

    <p>Gastrin secretion</p> Signup and view all the answers

    What is one factor that inhibits gastric emptying according to the text?

    <p>Inhibitory signals from the duodenum</p> Signup and view all the answers

    Which of the following can inhibit gastric emptying?

    <p>Excessive acidity in the chyme</p> Signup and view all the answers

    What is the role of CCK in the hormonal feedback related to gastric emptying?

    <p>Inhibiting gastric emptying</p> Signup and view all the answers

    What is the main function of Ileocecal valve?

    <p>To resist reflux from the cecum</p> Signup and view all the answers

    Which signals greatly increase peristalsis in the small intestine after meals?

    <p>Nervous signals</p> Signup and view all the answers

    What types of movements help to propel chyme in the small intestine?

    <p>Segmentation and peristalsis</p> Signup and view all the answers

    How does the mucosal muscle contribute to the movement of lymph in the small intestine?

    <p>By extending into intestinal villi to facilitate lymph flow</p> Signup and view all the answers

    Which sphincter is most critical for preventing aspiration of stomach contents?

    <p>Lower esophageal sphincter</p> Signup and view all the answers

    What process involves signaling between the pharynx and the swallowing center in the brain stem?

    <p>Deglutition</p> Signup and view all the answers

    Which structure is responsible for determining if a food bolus is small enough to be swallowed?

    <p>Epiglottis</p> Signup and view all the answers

    What increases barrier pressure to reduce the likelihood of aspiration during medical procedures?

    <p>Administering cricoid pressure during induction</p> Signup and view all the answers

    Which movement involves signaling between the pharynx and the brain stem?

    <p>Pharyngeal peristalsis</p> Signup and view all the answers

    What is the main function of the sphincter of Oddi in the GI tract?

    <p>Regulate bile and pancreatic juice entry into the duodenum</p> Signup and view all the answers

    Which structure is responsible for determining if a food bolus is small enough to be swallowed?

    <p>Pharynx</p> Signup and view all the answers

    What triggers the receptive relaxation of the stomach?

    <p>Swallowing</p> Signup and view all the answers

    During swallowing, what prevents food from entering the trachea?

    <p>Larynx movement</p> Signup and view all the answers

    What increases barrier pressure to reduce the likelihood of aspiration during medical procedures?

    <p>Glottis closure</p> Signup and view all the answers

    What is one factor that inhibits gastric emptying according to the provided content?

    <p>High barrier pressure</p> Signup and view all the answers

    What role do internal and external anal sphincters play in the digestive system?

    <p>Maintain positive resting pressure to prevent involuntary defecation</p> Signup and view all the answers

    What stimulates mass movements in the colon after a meal?

    <p>Distention of the stomach</p> Signup and view all the answers

    What prevents fecal matter from dribbling through the anus?

    <p>Tonic constriction of the internal anal sphincter</p> Signup and view all the answers

    Which stimuli induce sphincteric contraction in the digestive system?

    <p>Distal stimuli</p> Signup and view all the answers

    What is the primary purpose of mastication in the digestive process?

    <p>To aid in the digestion of cellulose membranes</p> Signup and view all the answers

    Why are newborns and individuals with transected spinal cords unable to control their external anal sphincter?

    <p>Weak intrinsic myenteric reflex</p> Signup and view all the answers

    What is the primary function of large circular contractions in the colon?

    <p>Mixing of chyme</p> Signup and view all the answers

    How many times is a typical food bolus chewed before passing through the esophagus without pain?

    <p>25-30 times</p> Signup and view all the answers

    Which reflex is essential for fortifying the parasympathetic defecation reflex?

    <p>Duodenocolic reflex</p> Signup and view all the answers

    What triggers the stretch reflex leading to rebound contraction during chewing?

    <p>Jaw dropping when a bolus of food is in the mouth</p> Signup and view all the answers

    Which muscle group is primarily responsible for mastication and is innervated by a motor branch of CN V?

    <p>Muscles of mastication</p> Signup and view all the answers

    What is the main function of teniae coli in the colon?

    <p>Propulsion of feces into the rectum</p> Signup and view all the answers

    What is the role of migrating motor complexes (MMCs) in the small intestine?

    <p>Interrupt at 90-minute intervals to move indigestible components</p> Signup and view all the answers

    What is the main function of the ileocecal valve?

    <p>Prevent backflow from the colon to the small intestine</p> Signup and view all the answers

    How does the mucosal muscle contribute to intestinal function?

    <p>Increase barrier pressure to reduce aspiration risk</p> Signup and view all the answers

    Which signals greatly increase peristalsis in the small intestine after meals?

    <p>Gastrin, CCK, insulin, motilin</p> Signup and view all the answers

    What factor primarily affects gastric emptying based on the information provided?

    <p>Tonicity of the chyme</p> Signup and view all the answers

    Which type of movements help propel chyme in the small intestine?

    <p>Peristaltic movements</p> Signup and view all the answers

    What is the primary action of the soft palate during the pharyngeal stage of deglutition?

    <p>Prevent food reflux</p> Signup and view all the answers

    How does the cricopharyngeus muscle behave during the pharyngeal stage of deglutition?

    <p>Relaxes to allow food passage</p> Signup and view all the answers

    What is the main function of the upper esophageal sphincter (UES) during deglutition?

    <p>Prevents gastric reflux</p> Signup and view all the answers

    Which structure plays a significant role in preventing regurgitation and aspiration of gastric contents?

    <p>LES pressure</p> Signup and view all the answers

    How is the barrier pressure calculated in the context of gastroesophageal reflux prevention?

    <p>LES pressure - Intragastric pressure</p> Signup and view all the answers

    What effect does pregnancy have on the lower esophageal sphincter (LES)?

    <p>Decreases LES tone</p> Signup and view all the answers

    Which condition is characterized by the failure of smooth muscle motility and relaxation of the lower esophageal sphincter (LES)?

    <p>Achalasia</p> Signup and view all the answers

    'Barrett's esophagitis' is associated with which transformation in the lower esophagus?

    <p>'GI metaplasia'</p> Signup and view all the answers

    'Carcinoma of upper esophagus' is most commonly related to which lifestyle factor?

    <p>'Smoking/alcohol use'</p> Signup and view all the answers

    'Gastroesophageal Reflux Disease (GERD)' can lead to which critical issue for patients with heartburn?

    <p>'Lower barrier pressure'</p> Signup and view all the answers

    Study Notes

    Propulsion and Mixing of Food in the Alimentary Tract

    Ingestion of Food

    • Ingestion of food involves the breakdown of food into smaller particles and mixing with digestive enzymes and acids
    • Mastication (chewing) is important for breaking down cellulose membranes, allowing digestive enzymes to act on food particles

    Three Main Functions of GI Tract

    • Churning: enhances digestion and absorption of nutrients
    • Propulsion: caudal movement of food/waste
    • Acts as a reservoir: facilitated by sphincters

    Sphincters

    • Specialized circular muscles that act as one-way valves
    • Regulate antegrade and retrograde movement
    • Proximal stimuli cause sphincteric relaxation, distal stimuli induce sphincteric contraction
    • Separate low-pressure organs, maintain positive resting pressure, and coordinate with adjacent organs by intrinsic and neurohumoral stimuli

    Mastication

    • Most muscles of mastication are innervated by the motor branch of CN V
    • Chewing is important for breaking down cellulose membranes
    • A bolus of food in the mouth causes the jaw to drop, followed by a stretch reflex and rebound contraction

    Deglutition

    • Three stages: voluntary, pharyngeal, and esophageal
    • Pharyngeal stage: involuntary, stimulated by sensitive epithelial swallowing receptor areas, and controlled by CNs IX, X, and XII
    • Esophageal stage: involuntary, assisted by gravity, and controlled by primary and secondary peristalsis

    Structures of the Esophagus

    • Upper esophageal sphincter (UES): skeletal muscle, controlled by extrinsic cranial nerves
    • Esophageal body: skeletal and smooth muscle, remains relaxed
    • Lower esophageal sphincter (LES): circular smooth muscle, controlled by ENS, and tonically constricted

    Motor Functions of the Stomach

    • During fasting, the stomach is quiescent
    • With ingestion of food, the stomach undergoes receptive relaxation, mixing waves, and gastric emptying
    • Gastric emptying is regulated by signals from the duodenum and stomach

    Regulation of Stomach Emptying

    • Factors promoting emptying: stretching of the stomach wall, gastrin, and activity of the pyloric pump
    • Factors inhibiting emptying: inhibitory signals from the duodenum, including CCK and hormonal feedback

    Movements of the Small Intestine

    • Segmentation movements: "chop" the chyme
    • Peristalsis: propels chyme, increased after meals
    • Migrating motor complexes (MMCs): interrupt at 90-minute intervals to move indigestible components

    Ileocecal Valve

    • Prevents backflow from the colon to the small intestine
    • Forcefully closed when excess pressure builds in the cecum
    • Resists reflux, and normally 1500-2000 ml of chyme empty into the cecum each day

    Principle Functions of the Colon

    • Absorption of water and electrolytes from chyme to form solid feces
    • Storage of fecal matter until expelled
    • Mixing movements: haustrations, and large circular contractions

    Defecation

    • Rectum is usually empty of feces
    • Dribble of fecal matter through the anus is prevented by tonic constriction of the internal and external anal sphincters
    • Defecation is stimulated by the gastrocolic and duodenocolic reflexes, and occurs 1-3 times a day

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    Propulsion and Mixing of Food PDF

    Description

    Test your knowledge on the sequence of events in the digestive system, from mouth to stomach to small intestine. Identify the process of mastication, secretion of gastric acid, and food movement through different organs.

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