Chapter 52, Problem 1O

Summary Introduction

To discuss:

The pathophysiology of vomiting and nausea including its specific precipitating factors and/or diseases.

Concept introduction:

Vomiting and nausea are the two gastrointestinal disorders. The unpleasant feeling that leads an urge in vomiting is called nausea. The forcible expulsion or emptying of intestinal contents through the mouth is called emesis or vomiting. A variety of stimuli are involved in triggering the feeling of nausea and vomiting are unpleasant sights, foul smell or taste, stomach or intestinal irritation, and the use of certain drugs.

Explanation of Solution

Vomiting center is responsible for the initiation of vomiting and nausea. Vomiting center is the area of the brain that is involved in the stimulation of nausea and vomiting. The chemoreceptor trigger zone (CTZ) is another area of the brain, which is also involved in the induction of vomiting and nausea. It sends neurotransmitter signals to the vomiting center about the presence of nauseating substances in the body. These signals alert the brain to expel the nauseating substances out from the body. The vomiting reflex will be initiated with the stimulation of CTZ and the vomiting center.

The neurotransmitters that are involved in the vomiting pathway includes acetylcholine (ACh), dopamine (D₂), histamine (H₁), prostaglandins, serotonin (5-HT₃), and substance P (Neurokinin 1).

The various areas or pathways that are involved in sending signals to the vomiting center in the brain are gastrointestinal tract, cerebral cortex, and labyrinth (inner ear).

The symptoms of vomiting could occur due to various factors such as stress, illnesses, and certain medications. Apart from this, two specific types of factors are also involved, such as post-operative and chemotherapy-induced nausea and vomiting.

Conclusion

The pathophysiology of nausea and vomiting, including its specific factors is discussed.