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.
FADH2 and NADH are created from FAD and NAD+ through redox (reduction-oxidation) reactions in the Krebs cycle during respiration as seen below here: This cycle gives off small amounts of energy in the form of ATP (adenonsine triphosphate, cell energy) and produces these compounds, FADH2 and NADH.