Question

Excessive stimulation of vagus nerve in humans may lead to-
A. Hoarse voice
B. Peptic ulcers
C. Efficient digestion of proteins
D. None of the above

Answer 1

Vagus nerve also called the pneumogastric nerve is the longest cranial nerve in the 12 cranial nerves of the body. It is the 10th cranial nerve or X cranial nerve and the longest cranial nerve. It has the most extensive distribution of the cranial nerves.

Complete answer:
The word ‘Vagus’ means wandering in Latin. The Vagus nerve is the most complex and mixed nerve that contains parasympathetic and sympathetic fibers. It runs from the brain to the abdomen via the face and thorax. It is the major component of the autonomic nervous system and has two sensory ganglia - superior and inferior. It is a part of a system that connects the neck, heart, lungs, and abdomen to the brain. It is majorly responsible for both sensory activities and motor information for movement within the body. Its sensory functions are divided into two components- Somatic (sensations felt on the skin or in the muscles) and Visceral (sensations felt in the organs). Its functions include- Metabolic homeostasis, balancing the nervous system, obtaining sensations from the throat, heart, lungs, abdomen, and tongue, movement functions for muscles in the neck, and maintains the heart rate, respiration, and digestive tract. Its fibers stimulate the parasympathetic nervous system of the stomach which stimulates gastric secretion, a dominant function of this nerve.

In the conditions of stress, the vagus nerve gets stimulated and sends a message to the body to relax. Excessive stimulation of the vagus nerve will stimulate excessive gastric secretion. Gastric acid hypersecretory state leads to peptic ulcer disease, gastroesophageal reflux, and gastrointestinal bleeding.
Let us analyze the options to find the correct answer.

Option A: Hoarse voice is the side effect of the vagus nerve stimulation for epilepsy. Therefore, this is the incorrect option.
Option B: Peptic ulcers occur when there is excessive stimulation of the vagus nerve as that affects gastric secretion. An increase in the secretion of gastric acid or peptic acid damages the lining of the stomach and causes painful soars which later forms ulcers. Therefore, this is the correct option.
Option C: The vagus nerve helps in the process of digestion but its overstimulation has no effect on the efficiency of the digestion of protein. Therefore, this is the incorrect option.
Option D: The correct option has been found therefore, this is the incorrect option.

Hence, the correct answer is option (B)

Note: Vagus nerve stimulation is also used for refractory epilepsy and as a treatment of mental depression which is generally untreatable. It is also explored for medical conditions like migraine and Alzheimer’s disease. Its excessive secretion affects gastrointestinal secretion. This nerve innervates the greater part of the digestive tract.