Anatomy of the Heart. Your heart is located under your ribcage in the center of your chest between your right and left lungs. Its muscular walls beat, or contract, pumping blood to all parts of your body. The size of your heart can vary depending on your age, size, and the condition of your heart.
In anaerobic respiration, NADH loses its electrons to other molecules in the process of fermentation for the purpose of regenerating the NAD+ needed to continue oxidizing organic molecules to produce ATP by substrate-level phosphorylation.
The Krebs cycle is like a wheel. Every time it makes one full rotation, energy is created and released. As you can see above, the NAD+ and FAD are brought in at key points throughout the cycle and are attached to other electrons resulting in the formation of NADH and FADH2. This energy is then shuttled off to be used by the cell, mostly for the continuation of cellular respiration.