Right then children.

We’re here at the beach to look at some of the things human bodies do to keep their temperature and water levels in perfect balance.

This guy has been sitting in the hot sun and he’s very sweaty, as you can see.

Drops of sweat forming in the glands under his skin have come up through tiny openings on the surface called pores.

When the sweat evaporates, it draws heat away with it and cools the body down.

When it’s hot, humans can sweat up to 5 litres a day, which is why it’s important for them to drink lots of water in hot weather.

Humans have a couple of very special organs that keep the amount of water in their blood at just the right level.

Let’s check them out with some virtual biology!

These are the kidneys, which sit just under the ribcage against the back.

Blood passes through the kidneys non-stop.

They clean the blood, filtering out nutrients, waste and water.

If a human has drunk lots of fluid and has more water in their blood than they need, the kidneys send the extra water down to the bladder together with waste products.

This then comes out of the body as wee.

If the body’s running low on water, the kidneys hold onto it and release it back into the bloodstream.

This means less water goes into the wee, making it more concentrated and darker in colour.

Us flies also need to keep our bodies in perfect balance.

Right now, for example, we could really use some fluid and some sugar.

Ooh look, a lollipop stick with a drop of juice…

SLURP

Argh! Sugar rush!!