Chapter 7.7, Problem 15SAQ

Summary Introduction

To explain:

How muscle tissue generates ATP during short-term and long-term exercise.

Introduction:

The transfer of hydrogen ion through a proton pump generates an electrochemical gradient of protons, called a proton gradient. This proton gradient, also known as proton motive force is responsible for the conversion of $\text{ADP}$ to ${\text{FADH}}_2$ (Flavin Adenine Dinucleotide) through the enzyme $\text{ATP}$ synthase.

Explanation of Solution

The energy source for muscle tissues are products of anaerobic as well aerobic respiration, which provide energy for short-term exercise. The oxidation of fatty acids, provide energy to the muscle tissues for long-term exercise.

Anaerobic respiration: The anaerobic source of energy for muscle tissues is lactic acid fermentation. The production of lactic acid from pyruvate releases energy in the form of $\text{ATP}$. The lactic acid along with $\text{ATP}$ are utilized by the muscle tissues.

Aerobic respiration: The aerobic source of energy for muscle tissue is generation of $\text{ATP}$ is the electron transport chain. The end product of the electron transport chain is a larger amount of ATP, which is utilized by the various tissues of the body.

Beta oxidation: The breakdown of triacylglycerol inside the cells, leads to the formation of glycerol and fatty acids. These fatty acids so formed, are further shortened by a series of reactions. This shortening of fatty acids results in sequential removal of two carbon units from their ends. This process is called beta oxidation, and the products of this process are $\text{NADH}$ and ${\text{FADH}}_2$. These products are responsible for providing electrons for the synthesis of $\text{ATP}$ by oxidative phosphorylation. This is the reason, beta oxidation of fatty acids provide energy for long term exercise.

Conclusion

ATP in the muscle cells is generated during exercise by lactic acid fermentation, aerobic respiration, and beta oxidation.