why do we breathe???

[twolemonsinthefruitbowl]

We get our energy from the food we eat, so why do we need oxygen as well?
My theory is that we need a gas exchange so that the carbon dioxide we produce as a by-product of metabolism can be removed from the body (after all, each breath is triggered by a build up of carbon dioxide in our cells, isn't it?).
Any medical people / biologists around????

you need the oxygen to burn the food - ie to release the energy for use. It needs to be fed to every cell in the body because that is where the energy stored in the digested food (glucose in the blood) is converted into usable energy in the cell.

Well, as far as I understand it...

Oxygen is a highly flammable gas and is essential for burning things, which is why a candle flame goes out when you put a jar over the top, after it has burned up all the oxygen inside the jar. Wood or coal etc also wouldn't burn in a room with no oxygen. Inside the body (in some clever way, that a smarter person than me would have to tell you) the cells burn the calories and produce energy and heat. It needs oxygen to burn things.

The lungs give the oxygen to your arteries which branch off into tiny blood vessels, called capillaries and take oxygen to every single cell.
When you burn something (like wood or coal) it makes carbon dioxide and so does the body, so when your blood gets back to your lungs, the carbon dioxide hops back into the lungs to be breathed out.

thank you so much, you two!

Respiration:

Oxygen + glucose --> carbon dioxide + water + ATP (the energy source used by all your cells)

Levels of CO2 in the blood do have an link to breathing and heart rate.

Glucose comes from the food you eat, as sugar itself or broken down or converted from other molecules by your enzymes in your digestive system.

Your metabolic rate is actually the rate at which (I.e. How fast) this reaction and others happen in your cells.

I can find you some links with animations, etc if you like.

an link a link

murkyminotaur - oxygen is not flammable but it is essential to allow burning - take the oxygen away and something burning will go out - the basis for most fire extinguishers.