Stephen, New Jersey asked:
If youíre drinking a milkshake or any other drink with a straw, when you finish, you can use your lungs to suck up all the last bits through the straw. It doesnít matter how hard you suck, why donít we choke?
Kat - Okay, I have done extensive research into this question myself last night with some rum-based cocktails. So, this isÖ.
Chris Smith: It would have to be rum or can it be anything?
Kat - Anything would work, yes, but Iíd like Margaritas. But, you canít really drink them through a straw and I will be publishing my results in the journal of Inebreology very soon. But, basically, the reason is, is that when youíre drinking a drink thatís a full drink, you create a vacuum in your mouth and thatís basically what forces the liquid up the straw. Youíre not really kind of sucking it up. Youíre actually dropping the pressure in your mouth and that causes the liquid to go up the straw. What happens when you get right down to the bottom of your drink is that thereís very little liquid there. So, if you start thereís not really a lot of liquid thatís gonna go up into your lungs even it was to get there. The other thing is that fluid is a lot heavier than air and when you actually do the motion of sucking something up from the bottom of your cocktail glass or your milkshake, you kind of form a barrier at the back of your throat with like soft palate or things like that. So, the dregs of fluid come up the straw, they get into your mouth, they kind of go 'phleh' into your mouth while the air gets..
Chris Smith: How it go again?
Kat - 'Phleh'
Chris Smith: Just checking.
Kat - Thatís the scientific term I think youíll find. It sort of goes 'phleh' into your mouth. They donít really make it to the back of your throat to go down your lungs, but if you are a clumsy or a very enthusiastic drinker. It is possible to inhale fluid into your lungs up a straw, but most of us have kind of learned how to drink so we donít do it.
Owdbadger asked the Naked Scientists: Hi, I'm an English scientist living in New Jersey, USA (born in Cambrideshire). I must have listened to nearly all your podcasts while mowing the lawn or driving to work (US radio is rubbish). I love the show. I've noticed that when people have finished a milk shake (or any other drink for that matter), and they suck in all the last bits and bubbles with a straw from the bottom of the glass, it doesn't matter how hard they suck, they never get any bits or bubbles in their lungs. I've tried it myself. Why don't we choke? Thanks Ste (short for Stephen) What do you think? Owdbadger, Fri, 12th Jun 2009
Blame it on the straws. Chemistry4me, Sat, 13th Jun 2009
I reckon it's the way you put your tongue sort of around the end of the straw, all the liquid runs into it instead of going straight down your neck Madidus_Scientia, Sat, 13th Jun 2009
The back of your mouth is extremely sensitive and is aware of very tenuous substances which are hanging around there. You swallow the foam down and don't breathe it in because of this protective mechanism which would make you stop inhaling. Most of these bubbles you refer to, will burst when they reach your palate / tongue - possibly because of the saliva. You could MAKE yourself choke if you fought the reflex - but that could get crud into your lungs so it's not to be recommended.