Why do we need to breathe?
 

Well, why?

Why do we need Oxygen?

Most of the effort that we output seems to be fuelled by chemical energy extracted from our food.
The amount of energy we extract from a breath of air must be quite small, yet- if you don't breathe for 2 or 3 minutes, you snuff it.

Why, when we can get so much energy out of our grub, are we still so dependent on air?

-started thinking about this sort of thing as ones mother has a collapsed lung at the moment...

The body needs oxygen because oxygen is involved in the last steps of ATP synthesis. ATP is a molecule is all of the body's cells that provide the cell with energy to carry out its tasks. One of the most important of these is a pump on the cell surface that regulates the concentration of molecules in the cell. Without ATP, therefore, the cells would die. Without cells, the basic building block of tissues and organs, the body itself cannot function. Thus, oxygen is vital to make this ATP.

For more details just do an internet search for something like "Why do our bodies need oxygen?" Such a search will provide more answers than this forum and you will get them more quickly.

Thank you, Keith.

Isn't the body complex? It's a miracle we're here at all, never mind conscious...

I'm sure there are more complex reasons as to the use of oxygen in the body, ones which I am nowhere near educated enough to comment on, let alone understand.

But oxygen is used in the synthesis of energy. Without oxygen, we cannot turn the stores of glycogen (maybe) into usable energy so we can function.

Look up the Krebs Cycle on Google. This goes into the detail of what keith williams summarised earlier in the thread.

Biochemistry is a fantastically complex and fascinating field - it's what got me interested in biology and ultimately lead me to a degree in Animal Biology twenty five years ago.
That and parasitology which is mesmerisingly disgusting.....:ok:

So why do we need sleep?

After all the body is still functioning, as must the brain.

Why do we need to reproduce ?