Which of the following is not true regarding the GI tract regulation?

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

Applied Physiology

Easy

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

Explanation

The statement that the Enteric Nervous System (ENS) cannot function independently is false.
The ENS is often called the 'second brain' or 'brain of the gut' precisely because it can operate autonomously, controlling local reflexes for motility and secretion without input from the central nervous system.
While the Autonomic Nervous System (ANS) modulates its activity, the ENS can function on its own, as confirmed by observations that GI activity is not abolished even when deprived of ANS input.

Option A: This statement is true. The myenteric (Auerbach's) plexus is located between the muscle layers of the gut wall and is primarily responsible for controlling GI motility, including the tone, rhythm, and velocity of contractions.
Option B: This statement is true. The submucosal (Meissner's) plexus is located in the submucosa and primarily controls local functions within the inner wall of the intestine, including GI secretion and blood flow.
Option D: This statement is true. The ANS modulates the ENS. Parasympathetic stimulation ('rest and digest') generally increases ENS activity, enhancing motility and secretion, while sympathetic stimulation ('fight or flight') is typically inhibitory.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Regulation of the Gastrointestinal (GI) Tract as background academic context rather than a clinical decision trigger.
Understanding the ENS is crucial for comprehending pathologies like Hirschsprung's disease, where the absence of enteric ganglion cells in a segment of the colon leads to a lack of motility and severe constipation.
Pharmacology often targets the ENS. For example, anticholinergic drugs decrease GI motility and secretions by blocking parasympathetic input to the ENS, which is useful in treating diarrhea or intestinal cramping.
What if? If a patient has a complete spinal cord transection above the thoracic level, their basic gut motility and secretion would continue due to the autonomous function of the ENS, although they would lose the CNS-mediated modulation and reflexes like the defecation reflex.

How to Approach the Question

First, identify the negative framing of the question: 'which of the following is not true'.
This means you need to evaluate each of the four statements and find the one that is factually incorrect.
Recall the key components of GI regulation: the two plexuses of the Enteric Nervous System (ENS) and the influence of the Autonomic Nervous System (ANS).
Evaluate Option A: Myenteric plexus and motility. This is a core function. The statement is likely true.
Evaluate Option B: Submucosal plexus and secretion. This is also a core function. The statement is likely true.
Evaluate Option C: ENS independence. The key feature of the ENS is its autonomy, often called the 'second brain'. A statement claiming it cannot function independently is a strong candidate for being the false statement.

Concept Tested & Keywords

Concept Tested: Regulation of the Gastrointestinal (GI) Tract
Stem keywords: GI tract regulation, enteric nervous system, myenteric plexus, submucosal plexus
Lead-in keywords: not true
Negative lead-in flag: The question asks for the statement that is NOT true, requiring identification of the false statement among the options.

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