25 Questions
What is the main function of GI motility?
Mixing and propelling ingested food for digestion and absorption
In which part of the GI tract does phasic contractions occur?
Lower esophageal sphincter
What type of muscle is predominant in the contractile tissue of the GI tract?
Unitary smooth muscle with gap junctions
What is the primary function of mass movements in the GI tract?
Moving food into the small intestine
Which part of the GI tract exhibits tonic contractions?
Orad region of stomach
What is the role of circular smooth muscle in the GI tract?
Decreases the diameter of the GI tract
Which of the following describes a direct action that promotes the urge to defecate?
Distention of the rectal wall
What is the primary function of segmentation contractions in the large intestine?
Create characteristic saclike segments called haustra
What triggers the urge to defecate once the rectum fills to 25% of its capacity?
Voluntary relaxation of the external anal sphincter
What is the main function of mass movements in the large intestine?
Move fecal material over long distances
In which part of the gastrointestinal tract does water absorption occur, leading to semisolid and increasingly difficult to move fecal material?
Distal colon
What prevents reflux from the cecum back into the small intestine?
Contraction of the ileocecal sphincter
Which part of a meal triggers an urge to defecate?
All of the above
Which of the following is true about the function of sphincters in the gastrointestinal tract?
They relax to allow the movement of contents by decreasing the pressure at rest.
What is the primary factor determining the frequency of slow waves in the gastrointestinal tract?
Interstitial cells of Cajal and gap junctions
Which phase of swallowing involves the soft palate being pulled upward and the epiglottis covering the opening of the larynx?
Pharyngeal phase
What controls the opening and closing of the lower esophageal sphincter during esophageal motility?
Vagus nerve stimulation
What is the primary function of the orad region of the stomach?
Gastric emptying
What regulates the frequency and force of gastric contractions during fasting?
Motilin and migrating myoelectric complexes
What is likely to inhibit gastric emptying?
CCK
What stimulates peristalsis in small intestine motility?
Release of serotonin by enterochromaffin-like cells
What triggers the release of motilin in the small intestine?
Phase III of migrating myoelectric complexes
Which physiological process does vomiting involve?
Peristaltic contractions from intestine to stomach
What is NOT a characteristic event during vomiting?
Opening of glottis
What happens to feces in the large intestine?
They are destined for excretion.
This lecture covers the definition of motility, mechanism of contraction of the GI tract, chewing, swallowing phases, characteristics of motility in different parts of the digestive system, mass movements, and the process of defecation.
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