It Makes Me Sick – Why?

[anaxcrosswords]

You see it all the time. A film or TV programme where a detective discovers some gruesome remains and is physically sick. Or someone will say to you “The sight of it actually made me sick”.
Why does the body react in that way?

[rockyracoon]

I've always presumed it's the smell that makes people sick, I know it would make me lose my breakfast.

[ummmm]

I had a knock on the door telling me my uncle had died. I puked.

[woofgang]

I think its the adrenalin rush that does it.

[RATTER15]

Apparently it is a defence of the body to reject the likes of such things that are potentially hazardous by making us feel sick. Maybe just a theory, I heard it somewhere I'm sure.

[Sqad]

The vagal centre (vomiting) is at the base of the brain and is "stitched on" by many switches, which include sight, smell and emotions, all if stimulated lead to vomiting.

Why some people and not others....i don't know....genetics? nurture or past experiences.

[Sqad]

"switched" ^

[Old_Geezer]

Must be some evolutionary advantage but blowed if I can think of what it might be. Maybe it ensures the attacker doesn't want to stick around your vomit attacking you ?

[heathfield]

Then there's folk who, if severely frightened or startled, wet themselves (or worse!). I suppose in that case, it's an evolutionary advantage. Carrying less weight, you can run away faster!

[anaxcrosswords]

Very interesting responses so far, and I'm wondering if there's some link to the 'fight or flight' theory (or in this case, maybe 'larf or barf').
But ummmm's response makes that idea problematical. It's true that some people are physically sick simply because they hear some very bad news - so there has to be a mental stimulus causing it.

[mccfluff]

i thought sqads response covered it pretty well.... (including the bad news part)

[pixie373]

Distress can cause it. I'm not sure if there's an evolutionary advantage- I'd assumed it's the bodies way of getting rid of something it doesn't want and emotional and physical health are so tied-in together, the body can have an inappropriate response.

[Bazile]

cigarette smoke makes me feel ill - so what's happening there ?

[snags]

Some info here re shock and resulting physical symptoms including vomiting:

http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Shock

[Mamyalynne]

That is smell and taste Bazile.

[Old_Geezer]

There is a difference between how and why. To stick around there has to be at least no disadvantage, and to be so widespread a reaction it suggests it's advantageous somehow.

[pixie373]

Not necessarily, og. I'm sure we can agree that a mental illness can affect your physical health and vice versa. Phobias and panic attacks are both over-reactions to a perceived threat. I imagine vomiting can be the same.

[anaxcrosswords]

I wonder if there's a link to eg laughing and crying? These are visible manifestations of emotional states. Fear/revulsion aren't visible as feelings (facially they can be, of course, but we're just animals with expressive faces; I don't think other animals can show these emotions facially?).
But I still puzzle over the connection between fear/revulsion and vomiting. Some brain message evidently leads to the production of bile and I suppose the body seeks to eject that, but still, why bile?

[Sqad]

It's not just bile.
When the vagal centre is stimulated (as described in my first post) the vagus nerve which originates in the vagus centre, passes out of the skull, through the neck, traversing the chest and on into the stomach.
When stimulated ....everything gastric kicks into action, including the secretion of bile.

[Greedyfly]

I've also questioned this. The smell of death is awful and could definitely make you sick. It's when people have recently died and people vomit that makes me mad - It just does not feel like a natural reaction to me

[Greedyfly]

Posted too quickly oops. But everyone reacts differently. But I've never felt the urge to vomit at death.