30 Questions
What is the primary function of the receptive relaxation of the stomach?
To accommodate food with minimal increase in pressure
What is the main factor that determines the rate of stomach emptying for liquids?
The volume of the liquid
What is the primary function of the hunger contractions (pangs) that begin 12-24 hours post-prandially?
To signal the body that it is time to eat again
What is a role of gastrin in the regulation of stomach emptying?
To increase the acidity of the gastric juice
What is the primary mechanism by which the duodenum inhibits the rate of stomach emptying?
By sending inhibitory signals to the stomach and pylorus
What is the first major process in the assimilation of nutrients?
Ingestion
What is the process of chewing food called?
Mastication
Which sphincter is responsible for preventing the backflow of stomach contents into the esophagus?
Lower esophageal sphincter (LES)
Which of the following is NOT a motor function of the stomach?
Absorption of nutrients
What is the name of the valve that separates the small intestine from the large intestine?
Ileocecal valve
What is the main function of the colon related to the absorption of water and electrolytes from chyme?
Progresses from fluid to solid along the colon
What stimulates mass movements that force feces into the rectum?
Duodenocolic reflex
Which part of the colon is responsible for slowly digging into and rolling over fecal matter?
Large circular contractions + teniae coli
What muscle controls the dribble of fecal matter through the anus?
External anal sphincter
When do mass movements, such as propulsive movements, usually occur?
1-3 times a day, especially for the first hour after breakfast
What reflex must fortify the weak intrinsic myenteric reflex for effective defecation?
Parasympathetic defecation reflex
Which structure plays a critical role in determining if a bolus of food is small enough to be safely swallowed?
Palatopharyngeal folds
What happens due to the signaling between the pharynx and the swallowing center in the brainstem?
Facilitated pharyngeal peristalsis
Which factor can inhibit gastric emptying according to the text?
All of the above
What is the purpose of the ileocecal valve according to the text?
All of the above
What are functions of the mucosal muscle according to the text?
All of the above
Which of the following can affect intestinal motility?
Both nervous and hormonal signals
Mass movements can lead to bowel movements.
True
The epiglottis is critical for determining whether a bolus of food is small enough to be swallowed safely.
False
The lower esophageal sphincter is the main concern for the risk of aspiration when a patient feels food from the night before sitting in their stomach just before induction.
False
Administering glycopyrrolate increases barrier pressure and decreases the likelihood of aspiration.
False
Swallowing is a simple reflex that does not involve signaling between the pharynx and the swallowing center in the brainstem.
False
Mass movements usually occur when the stomach is empty, approximately 12-24 hours after a meal.
True
The ileocecal valve is responsible for slowly digging into and rolling over fecal matter in the colon.
False
Gastrin is the primary factor that inhibits gastric emptying.
False
Study Notes
Propulsion and Mixing of Food in the Alimentary Tract
- Ingestion of Food:
- Mastication: chewing breaks down food into smaller particles, increasing surface area for enzymatic digestion
- Deglutition: swallowing involves signaling between pharynx and swallowing center in brain stem
- Motor Functions of the Stomach:
- Receptive Relaxation: vagally mediated, triggered by movement of pharynx and esophagus, allowing stomach to accommodate food
- Mixing and Emptying: stomach mixes food with acid and enzymes, then empties into duodenum at a rate suitable for digestion
- Regulation of Stomach Emptying:
- Factors Promoting Emptying: stretching stomach wall, gastrin, and insulin stimulate emptying
- Factors Inhibiting Emptying: duodenal distension, CCK, and irritants can inhibit emptying
Movements of the Small Intestine
- Segmentation Movements: "chop" chyme into smaller particles
- Peristalsis: propels chyme through small intestine
- Migrating Motor Complexes (MMCs): interrupt peristalsis at 90-minute intervals to move indigestible components through small intestine
Movements of the Colon
- Mixing Movements - Haustrations: slow movement of fecal matter exposing it to mucosal surface
- Mass Movements: propulsive movements stimulated by gastrocolic and duodenocolic reflexes, occurring 1-3 times a day
- Defecation: rectum is usually empty of feces; internal and external anal sphincters regulate defecation
Sphincters and Reflexes
- Ileocecal Valve: prevents backflow from colon to small intestine
- Lower Esophageal Sphincter: relaxation is critical for determining whether a bolus of food is small enough to be swallowed
- Gastrocolic and Duodenocolic Reflexes: stimulate mass movements in the colon
Clinical Relevance
- Aspiration Risk: lower esophageal sphincter relaxation is a concern for aspiration risk
- Barrier Pressure: increasing barrier pressure can decrease the likelihood of aspiration
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