Three Main Energy System

We require energy for each and every activity that is being performed whether physically or chemically. This energy is acquired from the food we eat. In order to release that energy, certain anabolic and catabolic reactions take place. The three main energy systems are ATP Pcr,glycolytic and oxidative; oxidative having three futher subgroups. These are discussed below

ATP Pcr

The ATP Pcr system is a constituent of Adenosine triphosphate and phosphocreatine. This energy system provides high energy in minimal time. The stored phosphates contain excessive/high energy which are broken down upon activity therefore releasing energy at a very fast rate. However, it experiences downfall or fatigue fairly quickly. The ATP Pcr can generate approximately
It acts upon releasing energy from dietary carbohydrates or their stored form in the liver i.e. glycogen. Serum glucose or glycogen is broken down to generate ATP by the process of glycolysis. Similar to the ATP Pcr system, this process is anaerobic i.e. no oxygen is required for this process. An estimation suggests that glycolysis can generate energy at the rate of 16 kCal/minute. This energy system releases moderate energy with moderate time. As physical activity increases, pyruvic acid converts to lactic acid is produced causing a decrease in power hence resulting in muscle fatigue. This chain effect is known as ‘fast glycolysis’ . If the physical activity continues, the third energy system comes into play i.e the oxidative
It utilizes more power and provides longer duration of energy. It generates energy equivalent to approximately 1o Kcal/day. Through oxidative system, ATP can be produced in three ways which are
1. Krebs Cycle
2. Electron Transport Chain (ETC)
3. Beta Oxidation

Krebs cycle

This cycle is a series of chemical reactions which aid the oxidation of glucose that was previously initiated during glycolysis. The Acetyl Coenzyme A enters the Krebs cycle where it is broken down into hydrogen and Co2. What happens is that the pyruvic acid (produced during the glycolytic system) enters the mitochondria where it transforms into AcA where it reconciles with the oxaloacetic acid to form citric acid which is a 6 carbon compound. Following this, more chemical reactions take place concluding to produce two molecules of ATP.

Electron Transport Chain

The byproducts of the chemical reactions in the Krebs cycle are Carbon dioxide and hydrogen which are respired by the lungs and are transported to the ETC with the help of carrier molecules FAD and NAD+ respectively. This entire process makes up a cycle as both the starting and ending product is Oxaloacetic acid. There are numerous chemical reactions in the ETC however, the oxygen and hydrogen combine to produce water; which in turn prevents