Breaking the seal

Thoie

So, everyone's been there. You're out for a while, have had a few drinks, chatting with friends. You've been out for a few hours. You go pee for the first time. From there on out you need to pee approximately every 33 seconds (OK, not quite, but it can feel like it sometimes) for the rest of the night.

What's the explanation of this? Are your kidneys/liver/some random organ working overtime to process the alcohol? Is your bladder shrinking on contact with alcohol? Does your brain release endorphins which make you feel that peeing is better than listening to that bloke at the bar tell you how rich he is? Does the smell of pub toilets set off some neolithic tribal instinct making you mark your territory at ever shorter intervals?

Kevster

It's because alcohol is a diuretic, which means that it makes your kidneys take more water from your blood; water which is then passed to your bladder and then excreted through your - umm - 'knob'. So, once that 'seal' is broken and you're still drinking more and more alcohol, Im sure you can see how more and more urine would be produced.

Thoie

So during the first few hours the alcohol is still being processed (by the liver?) and hasn't got as far as the kidneys, but once it hits there the first time the kidneys just keep pulling more and more water from your body for x amount of time (until the last of the alcohol has been processed?) and passing it? As I'm lacking a "knob", I'm OK with the word urethra

SomeDose

It's an interesting question. Alcohol isn't actually a true diuretic i.e. a substance which inhibits sodium reabsorption whereby water loss is a secondary effect. Instead, it has a diuretic effect by inhibiting vasopressin release. Since vasopressin regulates water balance (it causes the body to hold on to water), alcohol will cause the body to flush out water but not electrolytes (unlike true diuretics). This is why when you pee the urine will be very light or clear.

To answer the point though, I'm really not sure of the scientific basis behind this well-documented phenomenon of pub lore. I suspect it may have something to do with the fact that alcohol is unusual in that it exhibits saturation metabolism pharmacokinetics i.e. liver metabolism is not in proportion to the amount of drug in the blood, which means that it will have variable effects depending on its level in the blood. It may also have something to do with the kinetics of vasopressin, which I don't know much about at all. Personally, I experience the effect in the usual manner but it then seems to diminish over time so that after a few hours I'm peeing at a normal frequency again i.e. according to how much fluid I'm taking in. Which kinda suggests to me the body's osmo/baroreceptor influence on vasopressin is over-riding the inhibitory effect that alcohol has on it. Or maybe not. Answers on a postcard...

MrCreosote

Apart from the alcohol, there's all the water you take as well- over half a litre with every pint. Take the time lag from stomach to blood to kidney to bladder and I'd say that contributes a lot to breaking the seal. The alcohol itself has an effect of course but anyone know how beer compares with spirits?

Kevster

MrCreosote wrote: »

Apart from the alcohol, there's all the water you take as well- over half a litre with every pint. Take the time lag from stomach to blood to kidney to bladder and I'd say that contributes a lot to breaking the seal. The alcohol itself has an effect of course but anyone know how beer compares with spirits?

lol... ...yeh, I think that I was thinking too much with the whole 'diuretic' talk. All that water is bound to make your kidneys take more water out of your blood for excretion. Silly me (and SomeDose). Common knowledge and sense wins the day again.

Thoie

MrCreosote wrote: »

Apart from the alcohol, there's all the water you take as well- over half a litre with every pint. Take the time lag from stomach to blood to kidney to bladder and I'd say that contributes a lot to breaking the seal. The alcohol itself has an effect of course but anyone know how beer compares with spirits?

Well, I'm a spirit drinker, not a pint drinker, and I experience it. I'll generally have half a bottle of mixer with a measure of spirits, not sure what size the bottles are, but let's say that's 150ml of liquid at a go. I'd usually find that my first pee break might be slightly after the guys on pints, but after that the frequency is about the same, if not more frequent.

SomeDose

Kevster wrote: »

lol... ...yeh, I think that I was thinking too much with the whole 'diuretic' talk. All that water is bound to make your kidneys take more water out of your blood for excretion. Silly me (and SomeDose). Common knowledge and sense wins the day again.

Eh, speak for yourself pal! The diuretic effect is due to the alcohol itself, and the volume of urine excreted is usually significantly greater than that taken in i.e. even drinking small volumes of spirits will still produce the same effect (as Thoie will testify). Obviously the increased fluid volume from pints will also add to the diuresis but that's via a different mechanism (sort of).

*cracks open bottle of rum to test my own theory...