Here's a breakdown:

* The respiratory system: This system is responsible for taking in oxygen from the air and delivering it to the blood. It also removes carbon dioxide from the blood and releases it into the air.

* Cellular respiration: This is the process that occurs within cells to produce energy (ATP) from food. It requires oxygen and produces carbon dioxide as a byproduct.

Here's how it works:

1. Breathing: You inhale oxygen, which travels down your airways (nose, trachea, bronchi) to your lungs.

2. Gas exchange: In your lungs, tiny air sacs called alveoli allow oxygen to diffuse into the bloodstream, and carbon dioxide to diffuse out of the bloodstream.

3. Blood transport: The oxygen-rich blood is carried throughout the body by the circulatory system.

4. Cellular respiration: Cells use oxygen to break down glucose (sugar) and produce ATP (energy). Carbon dioxide is a waste product of this process.

5. Exhaling: Carbon dioxide is transported back to the lungs and exhaled.

So, the respiratory system provides the vital oxygen needed for cellular respiration, but it is not directly involved in the production of energy itself.