26.2 Upper Gastrointestinal Tract and Associated Accessory Digestive Structures
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Questions and Answers

What is the function of the esophagus?

  • Production of digestive enzymes
  • Storage of bile
  • Absorption of nutrients
  • Passage of food and drink (correct)

    • Which part of the body connects the mouth to the esophagus?

  • Glottis
  • Oropharynx (correct)
  • Larynx
  • Epiglottis

    • What causes reflux esophagitis?

  • Consumption of dairy products
  • Poorly protected stomach epithelium (correct)
  • Excess intake of vitamin C
  • Ingestion of large amounts of water

    • What condition may be mistakenly thought to be a heart attack due to its intense pain posterior to the sternum?

    <p><strong>Heartburn</strong></p> Signup and view all the answers

    Who is most likely to experience reflux esophagitis?

    <p><strong>Overweight individuals</strong></p> Signup and view all the answers

    Which factor can exacerbate the symptoms in individuals affected by reflux esophagitis?

    <p><strong>Eating spicy foods</strong></p> Signup and view all the answers

    What is the role of the tactile sensory receptors around the fauces during the swallowing reflex?

    <p>Stimulate nerve signals to the swallowing center</p> Signup and view all the answers

    What prevents ingested material from entering the trachea during swallowing?

    <p>Elevation of the larynx</p> Signup and view all the answers

    What is the function of the soft palate and uvula during the swallowing reflex?

    <p>Block the passageway between oropharynx and nasopharynx</p> Signup and view all the answers

    Why is a breath not taken during swallowing?

    <p>Nerve signals prevent it at the respiratory center</p> Signup and view all the answers

    What causes swallowed material to move from the pharynx into the esophagus?

    <p>Contraction of pharyngeal constrictors creating a pressure difference</p> Signup and view all the answers

    What is the duration of the pharyngeal phase during swallowing?

    <p>~1 second</p> Signup and view all the answers

    What is one of the most surprising changes noted following surgery?

    <p>Induction of type 2 diabetes into remission</p> Signup and view all the answers

    What is the purpose of gastric folds in the stomach lining?

    <p>Allow the stomach to expand greatly when filled with food</p> Signup and view all the answers

    Which structure extends inferiorly from the greater curvature of the stomach?

    <p>Greater omentum</p> Signup and view all the answers

    What is the purpose of the stress-relaxation response in the stomach wall?

    <p>To accommodate varying quantities of food</p> Signup and view all the answers

    Which smooth muscle response occurs after a prolonged stretch?

    <p>Relaxation after a period of time</p> Signup and view all the answers

    What endorsement does the International Diabetes Foundation give regarding gastric bypass surgery?

    <p>It endorses it for treating type 2 diabetes</p> Signup and view all the answers

    What is the primary function of smooth muscle activity in the stomach wall?

    <p>Mixing the bolus with gastric juice to form chyme</p> Signup and view all the answers

    Which hormone enters the blood instead of the lumen of the stomach?

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

    What is the consistency of chyme?

    <p>Pastelike soup</p> Signup and view all the answers

    Which cells produce somatostatin, a hormone that modulates nearby cells?

    <p>Enteroendocrine cells</p> Signup and view all the answers

    What occurs during gastric emptying in the stomach?

    <p>The pyloric sphincter opens to release chyme into the duodenum</p> Signup and view all the answers

    How does gastric mixing contribute to digestion?

    <p>By reducing the size of swallowed particles through churning</p> Signup and view all the answers

    What stimulates contraction of the pyloric sphincter to slow stomach emptying?

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

    Which phase of digestion involves processes following chyme reaching the small intestine?

    <p>Intestinal phase</p> Signup and view all the answers

    What hormone is released by the duodenum primarily in response to fatty chyme?

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

    Which reflex protects the small intestine from being overloaded with chyme?

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

    What causes a decrease in nerve signals relayed to the medulla oblongata in the intestinal phase?

    <p>Acidic chyme entering the duodenum</p> Signup and view all the answers

    What hormone causes a decrease in stomach motility in response to fatty chyme in the small intestine?

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

    What initiates sensory nerve signals to the salivary nuclei when one eats spoiled food?

    <p>Bacterial toxins in the stomach</p> Signup and view all the answers

    What leads to a more viscous saliva by decreasing the water content during exercise or excitement?

    <p>Sympathetic stimulation</p> Signup and view all the answers

    What results in additional saliva being released into the oral cavity?

    <p>Glossopharyngeal nerve (CN IX) innervation</p> Signup and view all the answers

    What is the possible cause of bad breath (halitosis) and dental problems when one has a dry mouth?

    <p>Decreased saliva production</p> Signup and view all the answers

    What is another term for chewing in the oral cavity?

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

    What decreases the fluid added to saliva by constricting blood vessels in the salivary gland?

    <p>'Sympathetic stimulation</p> Signup and view all the answers

    What is the main function of the esophagus?

    <p>Passage of food and drink</p> Signup and view all the answers

    What is a characteristic feature of reflux esophagitis?

    <p>Commonly known as heartburn</p> Signup and view all the answers

    Which factor is NOT associated with an increased risk of reflux esophagitis?

    <p>Having a small meal before bedtime</p> Signup and view all the answers

    What type of muscle tissue makes up the wall of the esophagus?

    <p>Skeletal muscle</p> Signup and view all the answers

    Why is reflux esophagitis more commonly seen in individuals with hiatal hernias?

    <p>Protrusion of part of the stomach through the diaphragm</p> Signup and view all the answers

    What distinguishes the esophageal epithelium from the stomach epithelium in terms of protection against acidic contents?

    <p>Esophageal epithelium lacks adequate protection</p> Signup and view all the answers

    What is one of the surprising changes noted following surgery?

    <p>Induction of type 2 diabetes into remission</p> Signup and view all the answers

    What is the function of the gastric folds in the stomach lining?

    <p>To accommodate varying quantities of food</p> Signup and view all the answers

    Which structure covers the anterior surface of abdominal organs like a fatty apron?

    <p>Greater omentum</p> Signup and view all the answers

    What is the characteristic response of smooth muscle to a prolonged stretch in the stomach wall?

    <p>Initial contraction followed by relaxation</p> Signup and view all the answers

    What endorsement does the International Diabetes Foundation give regarding gastric bypass surgery?

    <p>Endorsement for treating type 2 diabetes</p> Signup and view all the answers

    What is a function of the serous membrane known as the lesser omentum?

    <p>To connect the stomach to other abdominal organs</p> Signup and view all the answers

    What is the primary function of parietal cells in the stomach?

    <p>Creating a low pH environment</p> Signup and view all the answers

    Which cells in the stomach produce gastric lipase?

    <p>Chief cells</p> Signup and view all the answers

    What is the role of chief cells in the stomach?

    <p>Releasing pepsinogen</p> Signup and view all the answers

    What is the primary function of gastric emptying?

    <p>Moving chyme from stomach to duodenum</p> Signup and view all the answers

    What facilitates the movement of chyme through the pyloric sphincter into the duodenum?

    <p>Wave of peristaltic muscular contraction</p> Signup and view all the answers

    How does the pyloric sphincter prevent chyme from moving back into the stomach after gastric emptying?

    <p>By exerting higher pressure than the contents</p> Signup and view all the answers

    What is the primary function of the mucus layer produced by mucous cells in the stomach?

    <p>Preventing ulceration of the stomach lining</p> Signup and view all the answers

    Why is pepsinogen activated into pepsin in the stomach?

    <p>To prevent the destruction of chief cell proteins</p> Signup and view all the answers

    Where are mucous neck cells located in relation to the gastric pit?

    <p>Deep to the base of the gastric pit</p> Signup and view all the answers

    Which type of cells release an alkaline mucin to coat the epithelial lining in the stomach?

    <p>Mucous neck cells</p> Signup and view all the answers

    What is the main function of chief cells in the stomach glands?

    <p>Secrete pepsinogen granules</p> Signup and view all the answers

    How do mucous neck cells differ from surface mucous cells in terms of mucus production?

    <p>Mucous neck cells release alkaline mucin</p> Signup and view all the answers

    What enzyme in saliva initiates the chemical digestion of starch?

    <p>Salivary amylase</p> Signup and view all the answers

    Which structure provides lubrication to facilitate swallowing by secreting mucus in the superior part of the pharynx?

    <p>Soft palate</p> Signup and view all the answers

    What is the term for the wet mass formed when saliva mixes with ingested materials in the oral cavity?

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

    In which part of the upper gastrointestinal tract is the bolus mixed with gastric secretions?

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

    Which organ transports the bolus from the pharynx through itself into the stomach?

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

    What initiates mastication, the process of mechanical digestion, in the oral cavity?

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

    What is the primary effect of secretin on the stomach?

    <p>Inhibition of secretory activity</p> Signup and view all the answers

    Which hormone primarily regulates the release of insulin in response to increased glucose concentration in the small intestine?

    <p>Glucose-dependent insulinotropic peptide (GIP)</p> Signup and view all the answers

    What is the revised name for the hormone initially believed to regulate stomach activity but is now thought to primarily regulate insulin release?

    <p>Glucose-dependent insulinotropic peptide (GIP)</p> Signup and view all the answers

    What do both secretin and cholecystokinin (CCK) inhibit?

    <p>Release of gastrin</p> Signup and view all the answers

    In what specific section are the details about gastrin, secretin, and cholecystokinin (CCK) hormones discussed?

    <p>26.3c</p> Signup and view all the answers

    What was the initial belief about the hormone released from the small intestine called gastric inhibitory peptide?

    <p>It primarily regulated stomach activity</p> Signup and view all the answers

    What type of epithelium is found in the stomach mucosa?

    <p>Simple columnar epithelium</p> Signup and view all the answers

    Which cells in the stomach mucosa are often replaced within a week?

    <p>Surface mucous cells</p> Signup and view all the answers

    What structures extend deep into the mucosa from the base of each gastric pit?

    <p>Gastric glands</p> Signup and view all the answers

    Which part of the stomach lining is indented by numerous depressions called gastric pits?

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

    What surrounds the gastric glands and helps expel their secretions when it contracts?

    <p>Muscularis mucosae</p> Signup and view all the answers

    Which characteristic feature of the stomach wall contributes to digestion by containing invaginations within the mucosa?

    <p>Gastric pits</p> Signup and view all the answers

    What physiological responses occur prior to vomiting?

    <p>Increase in heart rate and sweating, feeling nauseous, increase in saliva production</p> Signup and view all the answers

    What is the primary force for the expulsion of digestive tract contents during vomiting?

    <p>Skeletal muscle contraction</p> Signup and view all the answers

    Why is it critical for individuals undergoing surgical procedures to have an empty stomach and small intestine?

    <p>To avoid inducing nausea and vomiting under general anesthesia</p> Signup and view all the answers

    What can extensive vomiting lead to?

    <p>Metabolic alkalosis</p> Signup and view all the answers

    What happens as pressure increases in the stomach during vomiting?

    <p>Gastric contents move up the digestive tract and are expelled through the mouth</p> Signup and view all the answers

    What region of the brain controls the vomiting reflex?

    <p>Vomiting center in the medulla oblongata</p> Signup and view all the answers

    What allows the stomach to expand greatly when filled with food and drink?

    <p>Gastric rugae</p> Signup and view all the answers

    Which smooth muscle response is a characteristic response of the stomach wall to a prolonged stretch?

    <p>Contraction then relaxation</p> Signup and view all the answers

    What is the term for the structure extending inferiorly from the greater curvature of the stomach?

    <p>Greater omentum</p> Signup and view all the answers

    Which organization now endorses gastric bypass surgery for treatment of type 2 diabetes?

    <p>International Diabetes Foundation</p> Signup and view all the answers

    What is an additional term for the serous membrane that forms a fatty apron over abdominal organs?

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

    What is one of the most surprising changes noted following surgery as mentioned in the text?

    <p>Induction of type 2 diabetes into remission</p> Signup and view all the answers

    Study Notes

    Pharynx and Esophagus

    • The pharynx connects the mouth to the esophagus, and the esophagus is a muscular tube that extends from the pharynx to the stomach.
    • The esophagus is normally collapsed and functions in the passage of food and drink.
    • The esophagus has three tunics in its wall.

    Reflux Esophagitis and Gastroesophageal Reflux Disease (GERD)

    • Reflux esophagitis is an inflammation of the esophagus caused by backflow of acidic stomach contents into the esophagus.
    • It is commonly known as heartburn and is more frequent in overweight individuals, smokers, and people with hiatal hernias.
    • Eating spicy foods or ingesting too much caffeine can exacerbate the symptoms.

    Swallowing Reflex

    • The swallowing reflex is initiated by the arrival of the bolus at the entryway to the oropharynx.
    • The bolus stimulates tactile sensory receptors around the fauces, which initiate nerve signals to the swallowing center in the medulla oblongata.
    • The response includes elevation of the soft palate and uvula, elevation of the larynx, and sequential contraction of the pharyngeal constrictors.

    Stomach Structure

    • The internal stomach lining is composed of numerous gastric folds, or rugae, which allow the stomach to expand greatly when filling with food and drink.
    • The stomach is able to accommodate varying quantities of food due to the stress-relax response of the smooth muscle in the stomach wall.

    Gastric Secretions

    • The stomach has two serous membrane structures: the greater omentum and the lesser omentum.
    • The stomach lining has a simple columnar epithelium supported by lamina propria, with numerous gastric pits and gastric glands.
    • The gastric glands produce and secrete various substances, including pepsinogen, gastric lipase, and intrinsic factor.

    Gastric Emptying

    • Gastric emptying is the movement of acidic chyme from the stomach into the duodenum of the small intestine.
    • The process is facilitated by the progressive thickening of the muscularis layer in the pyloric region.
    • The pyloric sphincter closes after the peristaltic wave has moved past, and the process is repeated to empty the chyme into the duodenum.

    Hormonal Regulation

    • Gastrin, secretin, and cholecystokinin (CCK) are hormones that regulate the digestive process.
    • Gastrin stimulates the release of gastric acid and pepsin.
    • Secretin and CCK inhibit the release of gastrin and decrease stomach motility.
    • Secretin causes the release of bicarbonate-rich pancreatic juices and stimulates the release of bile from the gallbladder.

    Intestinal Phase

    • The intestinal phase involves the processes following the chyme reaching the small intestine.

    • The intestinal reflex opposes the other two reflexes (cephalic and gastric reflexes) and protects the small intestine from being overloaded with chyme.

    • The release of cholecystokinin and secretin is stimulated by the entry of acidic chyme into the duodenum.### Vomiting Reflex

    • The vomiting reflex is controlled by the vomiting center in the medulla oblongata.

    • It responds to head injury, motion sickness, infection, toxicity, or food irritation in the stomach and intestines.

    Physiological Changes Prior to Vomiting

    • Heart rate and sweating increase, nausea is felt, and saliva production increases.

    Vomiting Mechanism

    • Vomiting is initiated following a deep inspiration and the closure of nasal cavities.
    • Skeletal muscle contraction (abdominal muscles and diaphragm) increases pressure within the stomach.
    • The acidic gastric contents are forced into and through the esophagus and out of the oral cavity.

    Complications of Vomiting

    • Aspiration of vomit into the respiratory tract is a risk for semiconscious or unconscious individuals.
    • Vomiting causes increased formation of HCl, leading to increased HCO3− in the blood, raising blood pH.
    • Extensive vomiting can lead to metabolic alkalosis.

    Gastric Anatomy

    • The internal stomach lining is composed of numerous gastric folds, or rugae, which allow the stomach to expand greatly when it fills with food and drink.
    • The stomach is able to accommodate varying quantities of food due to the stress-relax response exhibited by the smooth muscle within the stomach wall.

    Associated Structures

    • Two serous membranes structures are associated with the stomach: the greater omentum and the lesser omentum.
    • The greater omentum extends inferiorly from the greater curvature of the stomach, forming the fatty apron that covers the anterior surface of abdominal organs.

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