Motility and peristalsis Practice Questions
53 free Motility and peristalsis practice questions for the Physiology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Peristalsis in the gastrointestinal tract is best described as:
- A Simultaneous contraction of circular and longitudinal muscles
- B Waves of contraction and relaxation propelling contents forward
- C Localized mixing movements without any net propulsion of contents
- D Rhythmic opening and closing of gastrointestinal sphincters
Correct answer: Waves of contraction and relaxation propelling contents forward
Peristalsis consists of coordinated waves of contraction behind and relaxation ahead of a bolus. This pattern propels contents aborally through the gastrointestinal tract.
Which muscle layer contraction primarily narrows the lumen during peristalsis?
- A Longitudinal muscle
- B Oblique muscle
- C Circular muscle
- D Muscularis mucosae
Correct answer: Circular muscle
Contraction of the circular muscle layer reduces the diameter of the lumen. This is essential for pushing luminal contents forward.
Which nerve plexus primarily coordinates peristaltic movements?
- A Submucosal plexus
- B Myenteric plexus
- C Celiac plexus
- D Hypogastric plexus
Correct answer: Myenteric plexus
The myenteric plexus controls gastrointestinal motility. It coordinates smooth muscle contractions involved in peristalsis.
Which type of movement mainly serves a mixing function in the small intestine?
- A Peristalsis
- B Mass movement
- C Segmentation
- D Antiperistalsis
Correct answer: Segmentation
Segmentation involves rhythmic contractions that mix chyme with digestive juices. It enhances digestion and absorption rather than propulsion.
The primary pacemaker cells responsible for generating slow waves are:
- A Enteroendocrine cells
- B Mucus-secreting goblet cells
- C Interstitial cells of Cajal
- D Gut smooth muscle cells
Correct answer: Interstitial cells of Cajal
Interstitial cells of Cajal act as pacemakers of the gut. They generate slow waves that determine the rhythm of contractions.
Which gastrointestinal region has the slowest basic electrical rhythm?
- A Duodenum
- B Jejunum
- C Ileum
- D Stomach
Correct answer: Stomach
The stomach has the slowest basic electrical rhythm, about 3 cycles per minute. This sets the pace for gastric peristalsis.
Which hormone increases gastric motility and emptying?
- A Secretin
- B Motilin
- C Gastrin
- D Somatostatin
Correct answer: Gastrin
Gastrin stimulates gastric acid secretion and enhances gastric motility. It promotes mixing and emptying of stomach contents.
The migrating motor complex occurs primarily during:
- A Postprandial state
- B Fasting state
- C Fatty meal intake
- D Distension
Correct answer: Fasting state
The migrating motor complex occurs during fasting. It helps clear residual contents from the stomach and small intestine.
Which neurotransmitter is primarily excitatory for gastrointestinal smooth muscle?
- A Nitric oxide
- B Vasoactive intestinal peptide
- C Acetylcholine
- D Dopamine
Correct answer: Acetylcholine
Acetylcholine increases smooth muscle contraction in the gut. It enhances peristaltic activity and motility.
Which movement is characteristic of the colon to propel feces over long distances?
- A Segmentation
- B Peristalsis
- C Mass movement
- D Pendular movement
Correct answer: Mass movement
Mass movements are powerful peristaltic contractions of the colon. They move fecal matter toward the rectum.
Relaxation ahead of the peristaltic wave is mediated mainly by:
- A Acetylcholine
- B Substance P
- C Nitric oxide
- D Serotonin
Correct answer: Nitric oxide
Nitric oxide is an inhibitory neurotransmitter in the gut. It causes relaxation of smooth muscle ahead of the bolus.
Which factor most strongly initiates peristalsis in the intestine?
- A Acidity within the lumen
- B Stretch of the intestinal wall
- C Secretion of circulating hormones
- D Temperature of the contents
Correct answer: Stretch of the intestinal wall
Stretch of the intestinal wall activates local reflexes. This initiates peristaltic waves to propel contents forward.
The law of the intestine states that peristalsis proceeds:
- A In both directions from the stimulus
- B Only in the oral direction
- C Only toward the anus (aborally)
- D Randomly, based on neural input
Correct answer: Only toward the anus (aborally)
The law of the intestine states that peristaltic movement is aboral. Contents are propelled toward the anus.
Which structure prevents reflux of gastric contents into the esophagus?
- A Upper esophageal sphincter
- B Lower esophageal sphincter
- C Pyloric sphincter
- D Ileocecal valve
Correct answer: Lower esophageal sphincter
The lower esophageal sphincter prevents reflux of stomach contents. Its tonic contraction maintains a barrier against acid.
Which gastrointestinal movement predominates in the esophagus?
- A Segmentation
- B Peristalsis
- C Mass movement
- D Haustration
Correct answer: Peristalsis
Peristalsis is the primary movement in the esophagus. It propels the bolus from the pharynx to the stomach.
Haustral contractions are characteristic of which part of the gastrointestinal tract?
- A Stomach
- B Ileum
- C Colon
- D Esophagus
Correct answer: Colon
Haustral contractions occur in the colon. They aid in mixing and gradual movement of fecal material.
Which autonomic input generally decreases gastrointestinal motility?
- A Parasympathetic stimulation
- B Enteric nervous system activity
- C Sympathetic stimulation
- D Local reflex activation
Correct answer: Sympathetic stimulation
Sympathetic stimulation inhibits gastrointestinal motility. It reduces smooth muscle contractions during stress.
Which hormone slows gastric emptying by reducing motility?
- A Gastrin
- B Motilin
- C Cholecystokinin
- D Pancreatic polypeptide
Correct answer: Cholecystokinin
Cholecystokinin slows gastric emptying. This allows adequate time for digestion of fats in the small intestine.
Pendular movements primarily occur due to alternating contraction of:
- A Circular muscles only
- B Longitudinal muscles only
- C Circular and longitudinal muscles
- D Muscularis mucosae
Correct answer: Longitudinal muscles only
Pendular movements result from alternating contraction of longitudinal muscles. They contribute to mixing rather than propulsion.
Failure of relaxation of the lower esophageal sphincter leads to:
- A Gastroesophageal reflux disease
- B Achalasia
- C Peptic ulcer disease
- D Irritable bowel syndrome
Correct answer: Achalasia
Achalasia is caused by failure of lower esophageal sphincter relaxation. This impairs esophageal peristalsis and food passage.
Which of the following describes the electrical phenomenon known as 'slow waves' in gastrointestinal smooth muscle?
- A True action potentials that always trigger contraction
- B Rhythmic oscillations of the resting membrane potential
- C Rapid depolarizations caused by sodium influx
- D Inhibitory potentials generated by the sympathetic nervous system
Correct answer: Rhythmic oscillations of the resting membrane potential
Slow waves are not action potentials but rather cyclic depolarizations and repolarizations of the smooth muscle membrane potential. They establish the maximum frequency at which contractions can occur if the threshold for spike potentials is reached.
Which ions are primarily responsible for the 'spike potentials' that lead to actual contraction in the gut wall?
- A Potassium ions only
- B Potassium and chloride ions
- C Calcium and sodium ions
- D Magnesium ions only
Correct answer: Calcium and sodium ions
Spike potentials are true action potentials that occur when the slow waves reach a threshold (approx. -40 mV). These spikes are mediated by specialized calcium-sodium channels that open slowly, allowing calcium entry which directly triggers muscle contraction.
Which gastrointestinal region exhibits the highest frequency of the basic electrical rhythm (BER)?
- A Stomach
- B Duodenum
- C Ileum
- D Sigmoid colon
Correct answer: Duodenum
The frequency of slow waves varies along the GI tract, with the duodenum having the fastest rate at approximately 12 cycles per minute. In contrast, the stomach has a rate of about 3 per minute, and the ileum is about 8 to 9 per minute.
During a peristaltic reflex, what occurs in the segment of the intestine located immediately downstream (anal-ward) of the bolus?
- A Contraction of circular muscle and relaxation of longitudinal muscle
- B Relaxation of circular muscle and contraction of longitudinal muscle
- C Simultaneous contraction of both muscle layers
- D No change in muscle tone occurs
Correct answer: Relaxation of circular muscle and contraction of longitudinal muscle
To allow the bolus to move forward, the 'receptive relaxation' downstream involves the relaxation of the circular muscle layer. Concurrently, the longitudinal muscle contracts to shorten the segment, a process mediated primarily by inhibitory neurotransmitters like nitric oxide (NO) and VIP.
The Migrating Motor Complex (MMC) is a pattern of electromechanical activity that occurs primarily during which state?
- A Immediately after a high-fat meal
- B The cephalic phase of digestion
- C The interdigestive (fasting) state
- D During the peak of gastric acid secretion
Correct answer: The interdigestive (fasting) state
The MMC is a 'housekeeping' movement that occurs every 90-120 minutes during fasting to sweep residual undigested material and bacteria toward the colon. It is regulated largely by the hormone motilin.
Which of the following best describes the 'Vagovagal reflex' in the context of gastric motility?
- A Reflex that triggers vomiting after ingesting toxins
- B Relaxation of the stomach fundus as food enters
- C Contraction of the pylorus when acid reaches the duodenum
- D Urge to defecate after consuming a large meal
Correct answer: Relaxation of the stomach fundus as food enters
Receptive relaxation of the stomach is a vagovagal reflex where stretching of the esophagus and stomach causes the fundus to relax. This allows the stomach to accommodate a large volume of food with minimal increase in intragastric pressure.
A patient is found to have a lack of ganglionic cells in the myenteric plexus of the distal colon. What is the most likely clinical manifestation?
- A Rapid gastric emptying (Dumping syndrome)
- B Excessive watery diarrhea
- C Severe constipation and megacolon
- D Frequent gastroesophageal reflux
Correct answer: Severe constipation and megacolon
This describes Hirschsprung's disease, where the absence of the enteric nervous system (myenteric plexus) prevents peristalsis in the affected segment. This results in a functional obstruction, causing fecal buildup and massive dilation of the proximal colon.
What is the physiological significance of 'retropulsion' in the stomach?
- A It prevents food from entering the esophagus during a cough
- B It forces the bolus back to grind solids into finer chyme
- C It speeds emptying of liquids from the stomach to the duodenum
- D It signals the pancreas to release alkaline bicarbonate
Correct answer: It forces the bolus back to grind solids into finer chyme
When a peristaltic wave reaches the antrum, the pylorus closes. This forces the gastric contents back into the stomach, effectively grinding solid food into smaller particles (chyme) through mechanical shearing.
Which hormone is the primary mediator for inducing gallbladder contraction and simultaneously relaxing the Sphincter of Oddi?
- A Secretin
- B Gastrin
- C Cholecystokinin
- D Pancreatic polypeptide
Correct answer: Cholecystokinin
CCK is released by I-cells in the duodenum in response to fatty acids and amino acids. It coordinates bile delivery by contracting the gallbladder and relaxing the distal biliary sphincter (Oddi).
The 'Law of the Gut' (Polarity of the intestine) primarily refers to the fact that:
- A Absorption only occurs in the presence of sodium
- B Peristaltic waves always travel in the aboral direction
- C Acid is only secreted in the stomach
- D Blood flow increases during active digestion
Correct answer: Peristaltic waves always travel in the aboral direction
The Law of the Gut states that the intestine always propels its contents in the anal (aboral) direction. This polarity is established by the enteric nervous system, which coordinates contraction behind the bolus and relaxation ahead of it.
Which of the following will decrease the rate of gastric emptying?
- A Distension of the stomach wall by food
- B High blood levels of the hormone gastrin
- C High-osmolarity chyme within the duodenum
- D Parasympathetic vagal stimulation of the gut
Correct answer: High-osmolarity chyme within the duodenum
The enterogastric reflex and hormones like CCK and secretin slow gastric emptying when the duodenum is distended or contains acidic, fatty, or hypertonic chyme. This ensures the small intestine is not overwhelmed and has time to process the incoming nutrients.
Secondary peristalsis in the esophagus is distinguished from primary peristalsis because it:
- A Requires a swallow to be initiated at all
- B Is carried entirely by the glossopharyngeal nerve
- C Is triggered by local distension of the esophagus
- D Occurs only when the person is lying flat
Correct answer: Is triggered by local distension of the esophagus
Primary peristalsis is a continuation of the swallowing reflex. Secondary peristalsis occurs if a food bolus becomes stuck; the resulting distension triggers a local enteric reflex and vagovagal reflex to clear the esophagus without a second swallow.
Which movement is most responsible for the mixing of chyme with digestive enzymes in the small intestine?
- A Peristaltic rushes
- B Segmentation
- C Mass movements
- D Haustration
Correct answer: Segmentation
Segmentation involves localized concentric contractions of the circular muscle that divide the intestine into small segments. This 'back-and-forth' movement mixes the chyme with secretions and brings it into contact with the mucosa for absorption.
What characterizes 'mass movements' in the large intestine?
- A They occur every few seconds to mix the feces well
- B They are peristaltic waves occurring 1-3 times daily
- C They are limited to the ascending colon segment only
- D They are triggered by the release of the hormone secretin
Correct answer: They are peristaltic waves occurring 1-3 times daily
Mass movements are forceful, propulsive contractions that move fecal matter over long distances, usually from the transverse colon to the rectum. They are often triggered by the gastrocolic reflex after a meal.
The gastroileal reflex results in the relaxation of the ileocecal valve. What is the primary trigger for this reflex?
- A Acid in the duodenum
- B Distension of the rectum
- C Distension of the stomach
- D Presence of bile in the ileum
Correct answer: Distension of the stomach
The gastroileal reflex is an extrinsic/hormonal reflex where increased activity in the stomach (after eating) increases ileal peristalsis and relaxes the ileocecal sphincter, allowing chyme to pass into the cecum.
How do opioid medications (like morphine) typically affect gastrointestinal motility?
- A They stimulate the myenteric plexus and boost peristalsis
- B They block excitatory transmitters, causing constipation
- C They raise the frequency of gastric slow waves
- D They rapidly relax the internal anal sphincter muscle
Correct answer: They block excitatory transmitters, causing constipation
Opioids bind to mu-receptors in the enteric nervous system, which inhibits the release of acetylcholine. This decreases propulsive motility and increases fluid absorption, leading to opioid-induced constipation.
Which structure acts as the physiological pacemaker for gastric motility, and where is it located?
- A Interstitial cells of Cajal in the gastric fundus
- B Interstitial cells of Cajal in the mid-corpus
- C The myenteric plexus located at the pylorus
- D Vagus nerve terminals within the cardia
Correct answer: Interstitial cells of Cajal in the mid-corpus
The pacemaker for the stomach is located in the Interstitial Cells of Cajal (ICC) within the greater curvature of the mid-body (corpus). From here, slow waves propagate toward the antrum and pylorus.
During the defecation reflex, which of the following is under voluntary control?
- A Contraction of the sigmoid colon
- B Relaxation of the internal anal sphincter
- C Relaxation of the external anal sphincter
- D Peristaltic waves in the rectum
Correct answer: Relaxation of the external anal sphincter
The internal anal sphincter is composed of smooth muscle and is under involuntary autonomic control. The external anal sphincter is composed of skeletal muscle and is controlled voluntarily by the pudendal nerve.
What is the primary effect of sympathetic nervous system stimulation on the sphincters of the gastrointestinal tract?
- A Global relaxation to allow rapid transit
- B Tonic contraction (increased tone)
- C Rhythmic opening and closing
- D Sympathetic nerves do not innervate GI sphincters
Correct answer: Tonic contraction (increased tone)
In general, sympathetic stimulation inhibits the motility of the gut wall (via norepinephrine) but causes contraction of the sphincters (ileocecal, internal anal, etc.), effectively slowing the movement of contents during 'fight or flight'.
Which of the following neurotransmitters is the primary excitatory mediator of circular muscle contraction behind a food bolus?
- A Nitric Oxide
- B Acetylcholine
- C Vasoactive Intestinal Peptide (VIP)
- D Dopamine
Correct answer: Acetylcholine
Acetylcholine (along with Substance P) is the major excitatory neurotransmitter released by the myenteric plexus. It binds to muscarinic receptors on smooth muscle to cause the contraction that propels the bolus forward.
Which muscle layer primarily contracts to narrow the lumen during peristalsis?
- A Longitudinal muscle
- B Circular muscle
- C Mucosal muscle
- D Serosal layer
Correct answer: Circular muscle
Circular muscle contraction reduces the lumen diameter, pushing contents forward. It is essential for effective propulsion during peristalsis.
Relaxation ahead of the peristaltic wave is mainly mediated by which neurotransmitter?
- A Acetylcholine
- B Serotonin
- C Nitric oxide
- D Dopamine
Correct answer: Nitric oxide
Nitric oxide is an inhibitory neurotransmitter that causes relaxation of smooth muscle ahead of the bolus. This facilitates forward movement.
Which nerve plexus primarily coordinates gastrointestinal motility and peristalsis?
- A Submucosal plexus
- B Myenteric plexus
- C Cardiac plexus
- D Celiac plexus
Correct answer: Myenteric plexus
The myenteric (Auerbach's) plexus regulates motility and coordinates peristaltic movements. It lies between the circular and longitudinal muscle layers.
Which type of intestinal movement primarily serves a mixing function?
- A Peristalsis
- B Segmentation
- C Mass movement
- D Swallowing
Correct answer: Segmentation
Segmentation involves rhythmic contractions that mix intestinal contents. It enhances digestion and absorption.
Which gastrointestinal region has the highest frequency of slow waves?
- A Stomach
- B Duodenum
- C Ileum
- D Large intestine
Correct answer: Duodenum
The duodenum has the highest slow wave frequency, around 12 per minute. This supports rapid mixing and propulsion of chyme.
Which condition results from failure of relaxation of the lower esophageal sphincter?
- A GERD
- B Peptic ulcer
- C Diffuse esophageal spasm
- D Achalasia
Correct answer: Achalasia
Achalasia is characterized by failure of the lower esophageal sphincter to relax, leading to difficulty swallowing and esophageal dilation.
Which movement is characteristic of the esophagus during swallowing?
- A Segmentation
- B Mass movement
- C Peristalsis
- D Haustration
Correct answer: Peristalsis
Peristalsis is the primary movement in the esophagus, propelling food from the mouth to the stomach.
Haustral contractions are most characteristic of which part of the gastrointestinal tract?
- A Stomach
- B Ileum
- C Colon
- D Esophagus
Correct answer: Colon
Haustral contractions occur in the colon and help mix contents and facilitate absorption of water and electrolytes.
Pendular movements in the intestine are due to contraction of which muscle layer?
- A Circular muscle fibers
- B Mucosal muscle
- C Serosal muscle
- D Longitudinal muscle
Correct answer: Longitudinal muscle
Pendular movements result from alternating contraction of longitudinal muscles. They contribute to mixing of intestinal contents.
The law of the intestine states that peristalsis proceeds in which direction?
- A Bidirectional
- B Oral direction only
- C Random direction
- D Anal direction
Correct answer: Anal direction
Peristalsis normally moves in the anal direction, pushing contents toward the rectum. This is known as the law of the intestine.
Which movement propels feces over long distances in the colon?
- A Segmentation movements
- B Peristalsis
- C Haustration
- D Mass movement
Correct answer: Mass movement
Mass movements are strong peristaltic contractions that move feces over long distances in the colon, often leading to defecation.
Which neurotransmitter primarily excites gastrointestinal smooth muscle contraction?
- A Acetylcholine
- B Nitric oxide
- C Dopamine
- D Serotonin (5-HT)
Correct answer: Acetylcholine
Acetylcholine is the primary excitatory neurotransmitter in the gastrointestinal tract. It stimulates smooth muscle contraction.
The migrating motor complex primarily occurs during which state?
- A Fed state
- B Postprandial state
- C Sleep state
- D Fasting state
Correct answer: Fasting state
The migrating motor complex occurs during fasting and helps clear residual contents from the gastrointestinal tract.