What actually happens when the body has no oxygen as in what actually happens to muscles when no oxygen is entering the body?

Answer 1

the muscles get starved.

In order for the muscles to function, they need to carry our cellular respiration:

O2 + CH2O = ATPenergy + H2O +CO2

FOOD = ENERGY

If your "food" gets cut off, then your body will starve and shut down, because it cannot make any energy to function. It's the same with your cells. If your cells do not get enough oxygen or sugars, they will shut down because they cannot make enough energy nessecary for other cellular functions, such as active transport/endocytosis/exocytosis/etc. Likewise, if too many wastes build up (CO2) the cell will become poisoned, or too much wastes of H2O build up, then the cell will explode.

Furthermore, when water and carbon dioxide mix, an acid results:

H2O +CO2 = H2CO3

This creats an acidic environment within and around the cell (from natural diffusion of particles). The cell funcions best in slightly alkaline solution, so the acid created from excess waste from cellular respiriation results in certain cellular processes ceasing to work. You can think of that much like trying to digest protein in water: it won't work because protein digests best in a pH of 2 or less; that is why we have hydrochloric acid in our stomachs rather than water.

Also, a pH that is too far different from what our cells naturally have results in certain molecules in our cells to become mis-shaped. proteins get denatured in acidic environments, and most of the organelles are made of protein. If those organells are mutated, they will not function properly, and the cell will eventually die.

So, to conclude, if we don't breath, our cells will starve, stop working and become mis-shaped.