# Why is oxygen and blood important to working muscles?

Apr 3, 2016

Blood carries oxygen to the muscles for respiration, which releases energy to contract muscles.

#### Explanation:

Blood is important because it carries oxygen (${O}_{2}$) to the muscle cells and carries away carbon dioxide ($C {O}_{2}$).

Respiration is the process of converting the energy from glucose into ATP, which is a usable form for releasing energy to open ion channels, contract muscles, and aids many reactions in the body. ATP is often referred to as the energy currency of the body.

It full name is adenosine triphosphate, as it is an adenose sugar with three phosphate groups attached. When it releases energy, it breaks off a phosphate (${P}_{i}$) group and the energy in the bonds is released to the surroundings.

ATP cannot store energy for long, and so has to be made when and where it is needed, rather than stored in tissue, which means oxygen-rich blood has to be directed to the muscles when it is needed, such as in exercise.

The full reaction of respiration (ignoring all the stages in-between) is

${C}_{6} {H}_{12} {O}_{6} + 6 {O}_{2} \to 6 C {O}_{2} + 6 {H}_{2} O$

The carbon dioxide is released back into the blood for exhalation, and the water can be re-used.

The four stages of respiration are: glycolysis, link reaction, Krebs' cycle and Electron Transport Chain (ETC).