Ate something off for your last meal or heading out for a road trip? Just walked into an emotionally stressful situation or simply feeling under the weather? All or any of these situations can lead to nausea. Barfing, throwing up, puking, vomiting, regurgitation - call it whatever you will, it doesn’t make the experience any less unpleasant. However, sometimes, breaking down the process and understanding what really is going on in your body can make you feel better. (Or not, worth a try anyway.)
Nausea doesn’t exist in isolation - it’s often accompanied by sweating, dizziness, stomach ache and a chafed throat. Here’s a look at what’s truly going on when all that you’ve eaten decides to come rushing back.
When Nausea First Hits
Dr Ajay Aggarwal, Director, Internal Medicine, Fortis Hospital, Noida, defines vomiting as a “reflex action”.
"There are two primary reasons for vomiting - central and local. The first one stems in the brain and can be pathological or psychological. The second is linked to infections, acidity and so on." - Dr Ajay Aggarwal
When the body realises the presence of a toxic substance or something that needs to be rejected, the first signal is sent to the vomit centre of the brain which in turn sends another signal to the diaphragm and stomach muscles. The stomach muscles propel the food through the esophagus with great force.
The main triggers for this chain of actions are as follows:
- Ingestion of a toxic substance
- Stress hormones in the blood
- Motion like that of a vehicle or a swing (motion sickness)
- An upset stomach/indigestion
After a Threat is Detected
Once your body is all set to throw up, you will experience the following, according to this report:
- The mouth starts salivating - this is to make it alkaline to protect the teeth and the mouth from the stomach acid.
- Your heart beat increases and the skin starts to sweat to get rid of the heat produced by the process, and thereby regulate body temperature.
- The diaphragm contractions begin which squeeze the stomach, increasing the pressure on it which pushes the stomach content upwards.
- This pressure is further increased by the contraction of abdominal muscles.
- There’s also a deep breath involved which prevents the vomit getting into your lungs. The glottis shuts, preventing entry or exit of anything from the lungs.
- The exit at the bottom of the stomach called pyloric sphincter is also tightly shut. There is only one way for the movement of the rejected object.
How are the Various Threats Detected?
The threat detectors for the different reasons of nausea are also different.
- Brain’s chemoreceptor trigger zone detects hormones or toxic substances that are ingested.
- Inner ear has a role to play in case of motion sickness.
- Vagus nerve (a nerve that emerges directly from the brain) deals with an upset stomach.
- The central nervous system makes you throw up during times of extreme emotions
Once these responses are activated, the body begins a synchronised process that enables you to throw up.
A Little Something About Motion Sickness
Motion sickness happens as a result of mismatch between visual cues and the manner in which they are interpreted by the brain, which accordingly sends the signal to the stomach, points out this report.
For instance, if you’re in a car that’s going down a winding road, the physical movement of the car might churn up your stomach making it believe that a toxic or external substance has entered the body, especially if you’re reading or asleep, that is, the visual cues are not in sync with what’s happening to the stomach. Consequently, the body might want to throw up.
A good way to avoid it is to keep your eyes on the road. The visual cues would convey to the brain the reason behind the movement of the stomach. While there isn’t very concrete data based on it, several reports do support this theory. Try it for yourself next time a motion makes you feel sick.
Dr Aggarwal agrees with this and summarises it in the following manner:
"It’s important for the eye to focus on the visual before it and the retina to process the image or motion sickness will be triggered. To avoid it when in a vehicle, watch the road and look outside and not inside."
Emetophobia: Scared of Throwing-up? Yes, It's a Thing
There are people who feel anxiety and distress simply at the thought of vomiting - be it themselves or someone else. The intensity of this varies from being disturbing to debilitating for different people. The word used for it is emetophobia. While it’s rare, it’s not unheard of. Researchers are still trying to figure what exactly causes it.
According to this Dutch study, about 8 percent of the population is afflicted with it and that women are more likely than men to have it. The ratio is 4:1.
Severe cases of this phobia can lead to extreme aversion to any situation that might potentially cause nausea and an irrational avoidance of the same. It could include eating outside, going out for dinner, alcohol consumption, taking a road trip or even getting pregnant.
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