What Are Mitochondria?
Terminology: Mitochondria is the plural form of Mitochondrion and is often abbreviated to “Mito.”
Mitochondria are often referred to as the “Powerhouses” of our cells. Mito are bacteria-like organelles found in eukaryotic cells (cells that contain a nucleus). For humans, that would be all cells except our red blood cells. The purpose of Mitochondria is simple yet absolutely vital; they generate the chemical energy responsible for the very fact that we are alive. In fact, to truly die of “natural causes” means to simply fail to produce sufficient energy to maintain life.
This energy is referred to as Adenosine Triphosphate (ATP). It is the energy currency used to run every cell, organ, process, system and function in the body. How important is it to generate enough ATP? A healthy human will produce EACH DAY “your body weight equivalent in ATP.” And just like anything that runs on energy, if there isn’t enough, things stop working properly and can eventually lead to a number of different disease processes. (See Roles of Mitochondria in Human Disease.)
The good analogy of this breakdown from a lack of energy may be lost on younger generations, but here goes. Consider a battery operated cassette (tape) player. As batteries become weak and energy output diminishes, the interior components of belts and gears become inconsistent and jerky in their function. The more you play it, the slower it gets. The symptoms you might observe are an interruption of smooth functioning and a distortion of the speed and quality of the sound output. If you keep playing the tape despite the symptoms of a lack of energy, the player might even “eat the tape,” a crisis situation requiring immediate attention. But despite all you might attempt, if you don’t provide more energy, eventually the function completely fails.
Being the first physician to ever take the time to explain to me how the body works, I often borrow Dr. Derrick Lonsdale’s analogy of energy creation. He compares gas combustion in a car engine to that of food combustion within the Mitochondria. Remarkably, they are quite similar.
FUEL → OXYGEN → CATALYST = ENERGY (and EXHAUST)
For a car, fuel reacts with oxygen using a charged spark plug as a catalyst to cause combustion of the fuel to generate energy; and the leftover residue is what we know as exhaust. For a human, the process is very efficient despite being a complex, multi-step process that occurs inside Mitochondria called the Electron Transport Chain (ETC). The fuel is glucose extracted from fats, proteins, carbohydrates, and glycogen stores in the body. The glucose is broken down to Pyruvate and reacts with oxygen through a process called oxidation (combustion). Oxidation also requires charged spark plug-like catalysts; these are nutrients such as vitamins, minerals, fatty acids and amino acids that are required at different steps in the ETC. Oxidation can generate large quantities of ATP-energy, and the residue (exhaust) is known by many names: Reactive Oxygen Species (ROS), Free Radicals, Oxidative Stress, Oxidative Damage, etc.
There are other processes that create extremely small amounts of ATP that are insufficient to sustain complex (multi-cell) organisms like humans. Therefore, without the enabling levels of ATP-energy created by Mitochondria, we simply would cease to exist. We depend on both the number of Mitochondria per cell and how well they each function because the amount of available ATP impacts all aspects of health and optimal function. (See Mitochondria in Health and Disease: Perspectives on a New Mitochondrial Biology.)
There are many factors both inside and outside Mitochondria that can effect their function. There are also precursors and post-processes that affect how well Mitochondria function and recycle the energy production process. We will address these later but include:
Genetics
Nutrition and Hydration
Digestion
Breakdown and Delivery of Nutrient Chemical Compounds
Cellular Respiration
(Glycolysis, Pyruvate Oxidation, Krebs Cycle, Electron Transport Chain)
Anaerobic Respiration
NOTE: For a more scientific explanation that fully encompasses all aspects of each process of how Mitochondria generate ATP and the necessary nutrients involved in each step, please visit “Mitochondria: A Comprehensive Discussion.”