General Motility Disorders: Nausea and Vomiting

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  • 0:35 Nausea & Vomiting
  • 2:10 Why & How
  • 4:59 Testing & Treatment
  • 6:16 Fun Trivia
  • 6:51 Lesson Summary
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Lesson Transcript
Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

This lesson will explain what nausea, vomiting, and regurgitation are. We'll also explain how and why nausea and vomiting occur, how they can be treated, and a few other fun facts!

General Gastric Disorders

To those of you who have seen other lessons of mine, you know I love to help you make money while learning about science. So here's another way I'm going to help you out.

After one of your roommates or friends eats a bit more than they should and starts clutching at their stomach, they'll probably complain of pain and the need to rush off to the bathroom and will claim that they 'feel nauseous.'

And that phrase will be your cue to move in for the kill, or make some money, as this lesson's concepts about general gastric, or stomach-related, disorders will point out.

What Are Nausea, Vomiting, and Regurgitation?

So, when your one frat friend binged a bit too much on one too many beers, three 24-inch pizzas, and about 100 chicken wings, the first thing they will probably do is complain that they 'feel nauseous.'

Nausea is the sensation of wanting to vomit, while vomiting is the forcible expulsion of stomach contents through a person's mouth by way of involuntary muscular contractions. If vomit contains bright red blood, it's likely to have come from the esophagus, whereas digested, coffee ground-like looking blood in the vomit implies bleeding from the stomach or below.

Vomiting should not be confused with regurgitation, which is the movement of gastric contents into the mouth without nausea or forceful abdominal muscular contractions.

I doubt you didn't know that already, or how you should hold your friend's hair as they vomit, or the wonderful smell and visuals associated with all of that.

Just in case you didn't know, the things that can cause someone to vomit are extensive and include:

  • Pathogens, such as viruses and bacteria
  • Toxins, chemicals, poisons
  • Tumors
  • Liver disease

Quite literally, just about anything else you can think of, besides loads of cheap chicken wings and beer, can cause nausea and vomiting.

What's more interesting than the list of things that cause one to vomit is why it occurs.

Why and How Do Nausea and Vomiting Occur?

Nausea and vomiting can be triggered by way of stimulation of specialized nerve endings called receptors in the gastrointestinal tract. These mechanical and chemical receptors, called mechanoreceptors and chemoreceptors, can sense changes in the GI tract's environment that are initiated by toxins, bacteria, food, physical force (such as distension or obstruction), and so on.

If, for example, the chemical changes detected in the GI tract are dangerous enough, specialized cells, called enterochromaffin cells, release a compound called serotonin, also known as 5-HT, which then stimulates receptors called 5HT-3, which in turn tell the nerves that signal to the brain that something is wrong to begin firing away. Specifically, the pathways used to signal these messages to the brain include something known as sympathetic nerves and cranial nerve X, the vagus nerve.

I know what I said all sounds convoluted, but it can be easily distilled into a simple example. The serotonin is like your finger hitting a receptor on your keyboard, a letter key. Once you activate that key by pressing down upon it, it activates a nerve-like pathway, which sends an electrical signal to the hard drive, akin to your brain, that results in a message, the letter, appearing on your screen.

These signals, again, travel to the brain, especially the so-called vomiting center in the brain's medulla. It is these signals that cause nausea, and it is these signals that activate the vomiting center to send messages back down to the stomach, to the abdominal muscles, and to the esophagus.

The electrochemical messages leaving your brain cause your abdominal muscles to contract, thereby increasing pressure within your abdomen. The increased pressure trying to expel your stomach's contents combines with stomach contractions working in reverse, while your lower esophageal sphincter, the muscular gateway to your esophagus and therefore your mouth, relaxes to allow gastric contents to travel back up into and out of your mouth and into the toilet bowl.

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