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GI Peristalsis: Comprehensive Test Questions and Answers for Medical Students, Exams of Biology

North Carolina State University (NCSU)Biology

A comprehensive set of test questions and answers related to upper and lower gastrointestinal (gi) peristalsis. It covers key topics such as gerd, barrett's esophagus, gastric emptying, intestinal motility, and defecation reflexes. The questions delve into the physiological mechanisms, clinical implications, and regulatory factors involved in gi function, making it a valuable resource for medical students and healthcare professionals studying gastroenterology. It explores the roles of various hormones, neural pathways, and anatomical structures in the digestive process, offering a detailed understanding of gi motility and its disorders. The document also addresses clinical conditions like gastroparesis and dumping syndrome, providing insights into their causes, symptoms, and treatments.

Typology: Exams

2024/2025

Available from 06/03/2025

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PHY 503: UPPER AND LOWER GI PERISTALSIS: TEST
QUESTIONS WITH CORRECT ANSWERS
What is GERD? -- Answer โœ”โœ” incomplete LES closure allows stomach contents to
enter the lower esophagus and damage the esophageal wall
What are some complications of GERD? -- Answer โœ”โœ” esophageal stricture from scar
tissue, asthma resulting in aspiration, chronic sinus infections from reflux into the throat,
Barrett's esophagus
What is Barrett's esophagus? -- Answer โœ”โœ” chronic exposure to stomach contents
results in the normal stratified squamous epithelium of the esophagus being replaced
with simple columnar epithelium with goblet cells (similar to intestinal lining) as
esophagus tries to heal the damage
What is Barrett's esophagus a risk factor for? -- Answer โœ”โœ” esophageal cancer
What are rugae? -- Answer โœ”โœ” folds in the stomach lining
What happens when food enters the stomach? -- Answer โœ”โœ” receptive relaxation
occurs to make room for each food bolus entering (involves the vagus)
Why is receptive relaxation in the stomach considered a vagovagal reflex? -- Answer
โœ”โœ” sensory stretch signals are carried from the stomach to the CNS by the vagus
nerve, and the vagus also conducts efferent impulses to the orad (upper stomach) to
receive the food
What occurs as food moves to the caudal area of the stomach? -- Answer โœ”โœ” mixing of
food with gastric juice
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PHY 503: UPPER AND LOWER GI PERISTALSIS: TEST

QUESTIONS WITH CORRECT ANSWERS

What is GERD? -- Answer โœ”โœ” incomplete LES closure allows stomach contents to enter the lower esophagus and damage the esophageal wall What are some complications of GERD? -- Answer โœ”โœ” esophageal stricture from scar tissue, asthma resulting in aspiration, chronic sinus infections from reflux into the throat, Barrett's esophagus What is Barrett's esophagus? -- Answer โœ”โœ” chronic exposure to stomach contents results in the normal stratified squamous epithelium of the esophagus being replaced with simple columnar epithelium with goblet cells (similar to intestinal lining) as esophagus tries to heal the damage What is Barrett's esophagus a risk factor for? -- Answer โœ”โœ” esophageal cancer What are rugae? -- Answer โœ”โœ” folds in the stomach lining What happens when food enters the stomach? -- Answer โœ”โœ” receptive relaxation occurs to make room for each food bolus entering (involves the vagus) Why is receptive relaxation in the stomach considered a vagovagal reflex? -- Answer โœ”โœ” sensory stretch signals are carried from the stomach to the CNS by the vagus nerve, and the vagus also conducts efferent impulses to the orad (upper stomach) to receive the food What occurs as food moves to the caudal area of the stomach? -- Answer โœ”โœ” mixing of food with gastric juice

What do contractions in the stomach cause? -- Answer โœ”โœ” retropulsion of contents from caudad area to orad area, which throughout mixes the food with gastric secretions What does the antral pump in the caudad area of the stomach do? -- Answer โœ”โœ” propels chyme into the duodenum What are some factors that increase the rate of gastric emptying? -- Answer โœ”โœ” 1) increased tone of the orad

  1. forceful peristaltic contractions to propel contents toward the distal stomach
  2. decreased pyloric sphincter tone
  3. absence of segmental intestinal contractions Why must segmental intestinal contractions be absent to increase gastric emptying? -- Answer โœ”โœ” because the absence signals to the stomach that the intestines are not busy processing food, and are ready to receive the stomach contents What are some factors that decrease gastric emptying? -- Answer โœ”โœ” 1) peristaltic/digestive signals from the intestine
  4. relaxation of the orad --> enhances stomach storage function
  5. decreased force of peristaltic contractions --> less push of contents toward pylorus
  6. increased tone of pyloric sphincter --> makes it hard for distal stomach contents to pass into duodenum
  7. any segmentation movements in the intestine What are enterogastric reflexes? -- Answer โœ”โœ” changes to gastric function in response to the enteric (intestinal) environment How does CCK release in response to fat/proteins in the duodenum affect gastric emptying -- Answer โœ”โœ” increase gastric distensibility, which decreases gastric emptying How does acid affect gastric emptying rate? -- Answer โœ”โœ” decreases it via an intrinsic neural reflex What is gastroparesis and what are the symptoms? -- Answer โœ”โœ” delayed gastric emptying; symptoms can include fullness, bloating, loss of appetite, nausea, vomiting, and weight loss due to decreased food intake

What do segmental SI contractions do the the unstirred water layer adjacent to apical membranes of SI enterocytes? -- Answer โœ”โœ” disrupt it so that chyme can gain access to the channels on the epithelial surface, which increases absorption What is a migrating motor complex (MMC)? -- Answer โœ”โœ” rhythmic changes in motor and electrical activity that occur in the SI during the interdigestive (fasting) state What is the 4-phase pattern of an MMC? -- Answer โœ”โœ” 1) prolonged quiescent period

  1. period of increased AP frequency and contractility
  2. short period of peak electrical or mechanical activity
  3. period of declining activity that merges with the next quiescent period What is the function of MMCs? -- Answer โœ”โœ” to sweep undigested residue towards the colon to maintain low bacterial counts in the upper intestine What hormone is the major determinant of MMC pattern? -- Answer โœ”โœ” motilin How do we know that motilin does not have a role in digestive fed motor patterns? -- Answer โœ”โœ” because sham feeding (mimics eating without allowing food entry to the stomach) will terminate MMC patterns and initiate fed patterns of GI contractions Where do MMCs originate? -- Answer โœ”โœ” mostly from the stomach, but some in the duodenum and jejunum Why can food particles >2 mm in diameter pass from stomach to duodenum in the interdigestive period, but not during the fed state? -- Answer โœ”โœ” because in the fed state, pyloric sphincter tone creates a size restriction for any food that is entering the duodenum What is the gastroileal reflex? -- Answer โœ”โœ” promotes distal intestinal motility to clear out the distal intestine as a new meal is ingested and stretches the stomach; results in relaxation of ileocecal sphincter and increases in ileal peristalsis What is the intestino-intestinal reflex? -- Answer โœ”โœ” when severe distension of the part of the intestine inhibits the bowel

What hormones stimulate intestinal motility? -- Answer โœ”โœ” serotonin, prostaglandins, gastrin, CCK, and insulin What hormones inhibit intestinal motility? -- Answer โœ”โœ” epinephrine, secretin, and glucagon Why do patients on SSRIs tend to have GI side effects? -- Answer โœ”โœ” because increased serotonin alters gut motility What are the two functions of the ileocecal sphincter? -- Answer โœ”โœ” sphincter and valve What does the sphincter function of the ileocecal sphincter do? -- Answer โœ”โœ” regulates movement of ileal contents into the colon by controlling their rate of entry What does the valvular function of the ileocecal sphincter do? -- Answer โœ”โœ” prevents backflow of cecal and colonic material into the SI, ensuring unidirectional movement of contents and keeping colonic bacteria in the colon What happens to the ileocecal sphincter when luminal contents cause distension or pressure on the ileal wall? -- Answer โœ”โœ” the sphincter relaxes and ileal peristalsis is excited What happens to the ileocecal sphincter when luminal contents increase pressure on the colonic side? -- Answer โœ”โœ” the sphincter contracts and ileal peristalsis is inhibited Which nerve innervates the proximal colon? -- Answer โœ”โœ” vagus Which nerves innervate the distal colon, rectum, and anus? -- Answer โœ”โœ” S2-S What are hostral contractions? -- Answer โœ”โœ” contractions seen in the proximal intestine (similar to segmented contractions) that occur every 20-30 mins and further mix chyme to promote fluid/electrolyte absorption

  1. pharyngeal stage --> when the food passes through the pharynx to the uppermost part of the esophagus
  2. esophageal stage --> when the food passes from the esophagus to the stomach What are the epithelial swallowing center receptors? -- Answer โœ”โœ” areas in the back of the mouth and pharynx (especially on tonsillar pillars), that are stimulated as food enters and initiate autonomic pharyngeal muscle contraction What is the muscle contraction pattern of the beginning of the swallowing process? -- Answer โœ”โœ” 1) as swallowing begins, soft palate is pulled up toward the nares so food doesn't get into the nasal cavities
  3. larynx is pulled upward to move the epiglottis, which enlarges the opening of the esophagus
  4. UES releases and muscles in the pharynx contract to begin the pharyngeal stage of swallowing What is the role of the medullary swallowing center? -- Answer โœ”โœ” sensory input from pharynx and esophagus to the swallowing center coordinates vagal nuclei activity with other brainstem control centers, like inhibiting the respiratory center so breathing and swallowing do not occur at the same time What are the afferent and efferent signals involved in swallowing? -- Answer โœ”โœ” once food enters the pharynx, afferent input from vagus/glossopharyngeal nerves is sent to swallowing center nuclei; efferent signal is sent back to the pharynx to coordinate peristaltic contractions What is primary peristalsis in the esophageal stage of swallowing? -- Answer โœ”โœ” continuation of pharyngeal peristalsis that employs CNS involvement from the swallowing center Can primary peristalsis in the esophagus occur after vagotomy? -- Answer โœ”โœ” no, because it happens in the upper third of the esophagus which consists of striated muscle, so it is controlled by the PSNS

What is secondary peristalsis in the esophageal phase of swallowing? -- Answer โœ”โœ” peristalsis induced by distension of the esophagus due to local reflex signal throughout the enteric NS and the swallowing center Can secondary peristalsis in the esophagus still occur after vagotomy? -- Answer โœ”โœ” yes, because even though the swallowing center would not be functioning, the enteric NS could still function and allow automatic secondary peristaltic contractions to continue What is esophageal manometry? -- Answer โœ”โœ” measure of strength, muscle coordination, and pressure of the esophagus after swallowing What is the pressure like in the esophagus in between swallows? -- Answer โœ”โœ” high at both the UES and LES in order to ensure that the esophagus remains clear in the absence of food (UES prevents air entry and LES prevents stomach acid entry) What is the pressure like in the esophagus during swallowing? -- Answer โœ”โœ” UES pressure is lower because it relaxes, and the peristaltic wave is where we see the high pressure moving; LES and funds show low pressure, which is indicative of receptive relaxation in these regions in preparation for food bolus arrival What are the stages of GI motility? -- Answer โœ”โœ” ingestion of foods/liquids, propulsion along the GI tract, breakdown into absorbable components, and removal of remaining waste products What are three functions of GI motility? -- Answer โœ”โœ” 1) non-propulsive movement --

important for mixing food material

  1. peristalsis --> propels food bolus along the GI tract
  2. motor activity of hollow organs --> stomach and colon can serve as reservoirs for food, so their contractile function is somewhat different What would happen to peristalsis if the myenteric plexus were nonfunctional? -- Answer โœ”โœ” peristalsis would not occur