We all are aware that out bodies obtain its energy from metabolism. But do you know how this system works?. To understand what the Krebs Cycle is, you must first gain at least a basic understanding of what metabolism is. Metabolism can be defined as " The aggregate of all chemical processes that take place in living organisms, resulting in growth, generation of energy, elimination of wastes, and other body functions an they relate to the distribution of nutrients in the blood after digestion. Metabolism takes place in two phases:
- ANABOLISM- The constructive phase, in which smaller molecules, such as amino acids, are converted to larger molecules, such as protein.
- CATABOLISM- The destructive phase. A process by which larger molecules, such as glycogen, are broken down into smaller molecules, such as glucose.
* Definition from Mosbys medical dictionary 2002 edition Sixth edition page 1085
So how does Krebs relate to this. Simply put it takes glucose molecules and breaks them down into smaller molecules that out cells can use for food and energy. Our bodies use a substance known as Adenosine Triphosphate ( ATP ) for its energy, and we derive this energy from the Krebs Cycle. Again, it is best to define what something is, before more detail can be presented.:
KREBS CYCLE- AKA Citric Acid Cycle, A sequence of enzymatic reactions involving the metabolism of carbon chains of sugar, fatty acids, and amino acids to yields carbon dioxide, water, and high energy phosphate bonds. The cycle is initiated when pyruvate combines with Coenzyme A ( CoA) to form a two carbon unit, acetyl-CoA, which enters the cycle by combining with four carbon oxaloacetic acid to form a six carbon citric acid. In subsequent steps, isocitric acid, produced from citric acid, is oxidized to oxalosuccinic acid, which loses carbon dioxide to form alpha-ketoglutaric acid. Succinic acid, resulting from the oxidative decarboxylation of alpha-ketoglutaric acid, is oxidized to fumaric acid, and its oxidation regenerates oxaloacetic acid, which condenses with acetyl-CoA, closing the cycle. The citric acid cycle provides a major source of adenosine Triphosphate energy and also produced intermediate molecules that are starting points for a number of vital metabolic pathways, including amino acid synthesis.
**Mosbys medical dictionary 2002, sixth edition page 372
So what does all of this mean? The breakdown of molecules is an ongoing process. It never stops, even after death it continues for a short time. So basically what is occurring, is that a sugar molecule, specifically glucose. In chemistry, glucose is shown as the equation of C6H12O6, that is 6 molecules of carbon-12 molecules of hydrogen-6 molecules of oxygen. As it is broken down to citric acid ( C3H6O3 ), ATP is released.
Glucose is the primary source of all food and energy our cells can use. Without glucose, we lose approximately 90 percent of our ATP production ability. The cycle is of an aerobic substrate. Take away the glucose, we are left with anaerobic metabolism, which the end product is not ATP, but rather lactic acid. For those of you that are runners, you know those legs cramps and burning sensations you get?, this is the result of anaerobic metabolism, by which, there is not enough glucose in our systems to properly function. What is occurring is that instead of sugars being digested and processed, the body has to resort to the metabolism of muscle. This is why it gets so painful.
AEROBIC- With oxygen or air
ANAEROBIC- Without oxygen or air.
So what can we do to ensure anaerobic metabolism does not occur?. Make sure we are properly nourished, this means that sugars are a good thing. Ensure proper hydration, this allows for the sugar to be more fully diluted in order for Krebs to function the way it should. Exercise is critical, as it stimulates every aspect of our metabolic processes, but do not over do it, or you just might lose muscle tissue and tone.
On a slight side note, hope some of you can actually pronounce the names of these enzymes and sub-strates.