All of the following factors increase gastric motility?

RUHS, Jaipur, M.Sc Nursing Entrance Exam-2018

Applied Physiology

Easy

Appeared in: RUHS, Jaipur, M.Sc Nursing Entrance Exam-2018

Explanation

Abdominal distension, or the stretching of the stomach wall as it fills with food, is a primary stimulus for increasing gastric motility.
This stretching activates mechanoreceptors in the stomach wall.
Activation of these receptors triggers local myenteric reflexes and long-loop vagovagal reflexes.
Both of these reflex pathways lead to an increase in the force and frequency of peristaltic contractions, which promotes the mixing of food and accelerates gastric emptying.

Option B: Fear activates the sympathetic nervous system ('fight-or-flight' response), which inhibits gastrointestinal motility to conserve energy for more critical functions.
Option C: Similar to fear, stress activates the sympathetic nervous system, which slows down digestion and reduces gastric motility.
Option D: A vagotomy is the surgical cutting of the vagus nerve. This nerve provides the primary parasympathetic ('rest-and-digest') stimulation that promotes gastric motility. Removing this stimulation causes a significant decrease in motility.

Clinical Relevance

Nursing practice connection: Knowing Regulation of Gastric Motility helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Understanding factors that decrease gastric motility is crucial in managing gastroparesis (delayed gastric emptying), a condition common in patients with long-standing diabetes due to autonomic neuropathy affecting the vagus nerve.
Post-operative ileus, a temporary cessation of bowel motility, can be exacerbated by the stress of surgery and pain, which increase sympathetic tone.
Nurses should advise patients with delayed gastric emptying to eat small, frequent meals to avoid excessive gastric distension, which can worsen symptoms of bloating and nausea despite being a stimulus for motility.

How to Approach the Question

First, identify the core physiological process in the question, which is the regulation of gastric motility.
The question asks which factor increases motility. This requires you to evaluate each option's effect on the stomach.
Analyze the options in the context of the autonomic nervous system: parasympathetic ('rest and digest') vs. sympathetic ('fight or flight').
Recall that parasympathetic activity (via the vagus nerve) stimulates digestion and motility, while sympathetic activity inhibits it.
Evaluate each option: 'Abdominal distension' is a physical stimulus for digestion. 'Fear' and 'Stress' are triggers for the sympathetic system. 'Vagotomy' is the removal of the primary parasympathetic nerve.
Conclude that only abdominal distension serves as a direct stimulus to increase motility, while the other three options lead to a decrease.

Concept Tested & Keywords

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E6 Physiology Ganong 27e Vol 2 Part 1 pp. 45-47, 46-48

E6 Medicine Harrison 22e Part 1 p. 341-343