Kidneys,Yum.

This is gonna be a pretty short post coz it's like 9pm and I can't be bothered to cover much.

Okay, first of all, the Kidneys are found in your lower back and are given blood via the renal artery, and blood is taken away by the renal vein.

There are a couple of main parts I need to know for the Kidneys -

I don't really need to know about that Adrenal Gland, but that's the best diagram I can get.

Inside the Medula are these things called Nephrons, where all the bad stuff is filtered out of the blood.

It looks like....

As you can see in the diagram, the Renal artery feeds into the glomerulus, which is a ball of tiny capillaries. The capillaries allow the molecules in the blood to filter out, accept for blood cells and protein, which are too big. Those molecules that have been filtered out go into a cup-sorta-thing called the Bowmans Capsule, and then through a tube that leads to the Loop of Henle.

Coiled around the Loop of Henle are more capillaries which reabsorb the useful stuff in the blood. This blood is 'clean' and can continue its journey through the body. However, stuff that isn't useful, like excess water and urea go into the collecting duct, and then out of the body through the ureter.

The kidneys also help to control the amount of water in the body. There's a special sensor in the brain that detects if the water content is too low. If it is, it sends a message to another part of the brain to start producing ADH (anti-diuretic hormone), which tells the kidneys to reabsorb more water. This means we produce less urine, but what we do produce is very concentrated and dark in colour. This usually happens in warm weather, as we sweat out water.

Something similar happens if there's too much water in the body. The brain is instructed to produce less ADH, so the kidneys stop reabsorbing so much water. This means we produce more urine, which is less concentrated and pale. This happens in cooler weather because we don't sweat.

The end :)

Alcohol Doesn't Just Make You Drunk.

Before I get onto the delightful topic of alcohol, I need to clear up some stuff on Alkanes and Alkenes. If you're an unobservant person, you won't even have noticed the difference between those two words. If you are an observant, well, congratulations, but I have no prizes for you.

Basically, although they look pretty similar, they're different. Alkanes have single covalent bonds.

They're always made up of chains of carbon surrounded by hydrogen atoms (and sometimes some other stuff). Different alkanes have different lengths, but the four I need to know are Methane, Ethane, Propane and Butane. Careful with spelling - those 'ane's are important. Put an 'ene' by mistake and you've basically failed the exam.

All alkanes have the formula -

They're also all saturated, which means they've joined up to as many things as possible - there are no more bonds left to attach to. Which is why we can put alkanes into bromine water and see no reaction, which also allows us to tell the difference between alkanes and alkenes.

And speaking of alkenes - they're pretty much the opposite of alkanes. They have double covalent bonds, but once again are made up of mainly carbon and hydrogen atoms. This makes them unsaturated because the double bonds can open up to join with other things, hence making them into alkanes. So as a rule, alkanes are saturated, alkenes are not.

This also means that alkenes are much more reactive and react with bromine water to tell us what they are. The first three alkenes are ethene, propene and butene - remember what I said earlier about spelling?

All alkenes containing just one double bond have a formula like this -

So now that's all sorted, lets look at alcohol.

There's loads of different types of alcohol, but only one is safe to consume (well, ish). That's ethanol, which you get in wine and beer...etc. Where does ethanol come from? Sugar. The process of fermentation turns sugar into ethanol (and CO2, which is why alcoholic drinks have bubbles).

Here's the formula -

Tah dah, magical.

Anyways.

The whole reaction happens thanks to yeast which kinda acts like a catalyst. Yeast has enzymes in it that convert the suger into ethanol. Those enzymes are called 'zymase'.

As we all should know, enzymes have optimum temperatures, which explains why fermentation is very slow up until 30 degrees C, in which case it's pretty fast, and after which, doesn't really happen at all because the ezymes have denatured.

One of the most important factors in the fermentation is the lack of oxygen. Conditions need to be air tight, coz as soon as you get a bit of oxygen, bang, you get nothing.

Fermentation is actually turning out to be a bit of an annoying process, because when the alcohol percentage reaches between 10-20%, the reaction stops because the ethanol kills the zymase.

But there are good things about alcohol, like the fact we can use barley to make beer and fruit to make wine. We can then distil the alcohol to make it stronger (brandy is basically distilled wine, whiskey is distilled from fermented grain and vodka comes from fermented grain or potatoes. Yuk). Oh, and for those countries that don't have the resources to make petrol, ethanol is a great substitute, plus the ingredients are renewable!

There's more than one way of making ethanol though - we can react ethene with steam to make it too. For this to work it needs to be really hot (I'm talking 300 degrees) and have a pressure of 70 atmospheres AND a catalyst. Might sound tricky, but this is an easy process, mostly because ethene is cheap... but it comes from crude oil, which is an non-renewable resource.

But that's no where near all of alcohol covered. That's just the nice, safe-ish one. There are loads more, namely Methanol, Propanol and Butanol. They look like this...

Methanol. Propanol. Butanol

And Ethanol fits in the middle, right between methanol and propanol.

These alcohols are all clear, colourless and dangerous. They're flammable, evaporate easy, give off fumes and are all toxic. I'm serious, methanol will make you go blind if you drink it. So that's why all this stuff needs to be kept in safe environments - air tight bottles, away from flames and heat sources and preferably in a lab.

Alcohols can all dissolve into water, but are also used to dissolve stuff (they're solvents). They can dissolve everything that water can, plus hydrocarbons, oils and fats. Which makes them all very useful in industry. Eg. Ethanol is the solvent for perfume and aftershave. Methylated spirit (meths) is basically ethanol with other chemicals added to it. It's used to clean paint brushes (god knows why), and as a fuel. It's super dangerous though, so a purpley-blue dye is usually added to warn people.

Finally, ethanol can be dehydrated back into ethene. Industry involved in plastics and polymers use a lot of ethene, and countries with have no oil but lots of land to grow crops can make ethanol then turn it into ethene for whatever they need, But they have to use hot aluminium oxide as a catalyst - not so simple.

Tah dah, that's alcohol covereddddd :)