Physiology of Vomiting - Vomiting reflex (NEW)

Summary

This video delves into the physiology of vomiting, also known as emesis. It explains the involuntary process as the forceful expulsion of stomach contents through the mouth, triggered by the vomiting reflex. The medulla oblongata in the brainstem houses the vomiting center, which initiates the reflex upon stimulation by muscarinic receptors. The chemoreceptor trigger zone (CTZ), located outside the blood-brain barrier, is sensitive to chemicals like those in chemotherapy and motion sickness. It interacts with the vomiting center to induce vomiting. The video also covers the role of the vestibular system in motion sickness and how higher brain centers respond to emotional states and sensory inputs to trigger vomiting. Finally, it outlines the physiological changes during vomiting, including muscle contractions and autonomic responses.

Takeaways

• 🤮 Vomiting, also known as emesis or throwing up, is an involuntary, forceful expulsion of stomach contents through the mouth.
• 🧠 The vomiting reflex is controlled by the vomiting center located in the medulla oblongata of the brainstem, which contains muscarinic receptors.
• 🧪 The chemoreceptor trigger zone (CTZ), situated outside the blood-brain barrier, is sensitive to chemicals and can be stimulated by drugs like those used in chemotherapy.
• 🚫 The blood-brain barrier protects the brain from circulating substances, but the CTZ's location outside this barrier makes it more susceptible to such substances.
• 🌀 Motion sickness, caused by the inner ear's vestibular system, can stimulate the CTZ, leading to the vomiting reflex.
• 🤰 Morning sickness is another condition that can trigger the vomiting reflex, often due to hormonal changes during pregnancy.
• 🤢 The cerebrum can also initiate vomiting through the vomiting center when processing sensory information related to strong smells or sights.
• 🔁 The stomach's enterochromaffin cells release serotonin in response to cytotoxic agents, which can trigger the vomiting reflex via the vagal nerve.
• 🔁 The vomiting reflex involves the relaxation of the lower esophageal sphincter, contraction of the diaphragm and abdominal muscles, and closure of the epiglottis to prevent aspiration.
• 🤧 Autonomic changes during vomiting include increased heart rate, salivation, and peristalsis, which all contribute to the forceful expulsion of stomach contents.

Q & A

What is vomiting also known as?

Vomiting is also known as emesis and throwing up, amongst many other terms.

What is the involuntary forceful expulsion of stomach contents through the mouth called?

The involuntary forceful expulsion of stomach contents through the mouth is called the emetic reflex or the vomiting reflex.

Where is the vomiting center located in the brain?

The vomiting center is located in the medulla oblongata of the brainstem.

What types of receptors are found in the vomiting center?

The vomiting center contains muscarinic receptors.

What is the chemo receptor trigger zone (CTZ) and where is it located?

The chemo receptor trigger zone (CTZ) is an area near the medulla oblongata that gets triggered by chemicals and is located outside the blood-brain barrier.

Which receptors are found in the chemo receptor trigger zone (CTZ)?

The CTZ contains dopamine 2 receptors and 5-HT receptors, which are serotonin receptors.

How does motion sickness relate to the vomiting reflex?

Motion sickness, which originates from the inner ear's Labyrinth, can stimulate the vestibular nuclei, which then sends signals to the CTZ, leading to the vomiting reflex.

What is the role of the higher brain centers in initiating the vomiting reflex?

The higher brain centers can sense emotional overwhelm, severe pain, bad smells, or repulsive sights and send signals to the vomiting center to initiate the vomiting reflex.

How do interoceptive cells in the stomach contribute to the vomiting reflex?

Interoceptive cells in the stomach release serotonin in response to cytotoxic agents, which can stimulate 5-HT3 receptors on sensory nerve fibers, leading to the activation of the vomiting center.

What happens during the vomiting reflex that facilitates the expulsion of stomach contents?

During the vomiting reflex, the lower esophageal sphincter relaxes, the diaphragm and abdominal muscles contract to increase intra-abdominal pressure, and the epiglottis closes to prevent food from entering the lungs.

What autonomic changes occur during the vomiting reflex?

Autonomic changes during the vomiting reflex include an increase in heart rate (tachycardia), increased salivation, and peristalsis.