So our cells undergo lactic acid fermentation to basically regenerate the NAD plus molecules needed for glycolys to actually continue. So any type of cell that uses anaerobic respiration will generate these lactate molecules. And two examples that we're going to focus on, the two dominant types of cells that actually use anaerobic respiration are red blood cells and skeleton muscle cells. Let's focus on skeleton muscle cells. So skeleton muscle cells are the cells that use ATP to basically contract the act of mice and filaments. And that allows voluntary motion.