What Happens During Vomiting? | The GutDr Explains (3D Gut Animation)

Summary

In this video, Dr. Vincent Ho, a gastroenterologist, explains the fascinating process of vomiting. He explores the two main pathways involved: the central and peripheral pathways, and how signals from the brain and gut trigger vomiting. The video details the roles of the chemoreceptor trigger zone and various neurotransmitters like NK1, dopamine, and serotonin in this process. Dr. Ho describes the three phases of vomiting: pre-ejection, ejection, and post-ejection, and explains how the body expels stomach contents through rhythmic muscle contractions. Viewers are also encouraged to visit his website for more information and to subscribe for upcoming content on gut health.

Takeaways

• 😀 Vomiting (emesis) is the forceful expulsion of stomach contents, involving coordination of central and peripheral pathways.
• 😀 The emetic response is controlled by the brainstem's emetic center, which coordinates the vomiting process.
• 😀 The central pathway for vomiting signals originates from areas like the cerebral cortex, hypothalamus, and vestibular system.
• 😀 The peripheral pathway carries vomiting signals through the vagus and splenic nerves from receptors in the gut.
• 😀 The chemoreceptor trigger zone, located outside the blood-brain barrier, can trigger vomiting in response to toxins, medications, or metabolic products.
• 😀 Receptors in the chemoreceptor trigger zone, like NK1, dopamine, and serotonin receptors, play key roles in inducing nausea and vomiting.
• 😀 NK1 receptors, which bind strongly with substance P, are involved in the final common pathways leading to vomiting.
• 😀 The vomiting reflex occurs in three phases: pre-ejection, ejection, and post-ejection.
• 😀 Nausea often precedes vomiting and is accompanied by symptoms such as increased heart rate and muscle weakness.
• 😀 Wretching marks the ejection phase, involving rhythmic contractions of abdominal and chest muscles that force stomach contents into the esophagus.

Q & A

What is vomiting and how does it occur?

Vomiting, also known as emesis, is the forceful expulsion of stomach contents. It occurs through a coordinated response involving two pathways: the central and peripheral pathways, which are controlled by the emetic center in the brainstem.

What are the two pathways involved in vomiting?

The two pathways are the central pathway and the peripheral pathway. The central pathway involves signals from the brain, while the peripheral pathway involves signals from the gut, carried by nerves like the vagus and splenic nerves.

What role does the emetic center play in vomiting?

The emetic center, located in the brainstem, coordinates the vomiting response by receiving signals from both the central and peripheral pathways, triggering the physical act of vomiting.

What is the chemoreceptor trigger zone (CTZ) and what is its role in vomiting?

The chemoreceptor trigger zone is a region in the brainstem located outside the blood-brain barrier. It detects circulating toxins and triggers vomiting when exposed to harmful substances such as bacterial toxins or certain medications.

What neurotransmitters are involved in the vomiting process?

Several neurotransmitters play a role in vomiting, including dopamine, serotonin, acetylcholine, substance P, and neurokinin 1 (NK1). These neurotransmitters bind to receptors in the emetic center and the chemoreceptor trigger zone to trigger vomiting.

How does substance P contribute to vomiting?

Substance P binds strongly to NK1 receptors, which are found in high concentrations in both the emetic center and the chemoreceptor trigger zone. This binding is believed to be involved in the final stages of the vomiting process.

What are the three phases of the vomiting reflex?

The three phases of vomiting are: 1) Pre-ejection phase, where nausea and other symptoms like fast heart rate occur; 2) Ejection phase, marked by intense muscle contractions that expel stomach contents; and 3) Post-ejection phase, where the body recovers and the airways are protected.

What happens during the pre-ejection phase of vomiting?

During the pre-ejection phase, symptoms like nausea, increased salivation, and rapid heart rate occur. The stomach contents begin to move back into the stomach due to reverse peristalsis, and the body prepares for vomiting.

How does the body protect the airways during vomiting?

The body protects the airways by closing the glottis during the ejection phase, ensuring that food does not enter the airways. The upper esophageal sphincter also closes off to prevent aspiration of stomach contents.

What is the role of wretching in the vomiting process?

Wretching is an involuntary reflex that occurs during the ejection phase. It involves intense contractions of the chest wall, diaphragm, and abdominal muscles, increasing pressure in the stomach and forcing its contents into the esophagus.