Where Does Energy Come From?

All energy on earth comes from the sun. Plants use the light energy from the sun to form carbohydrates, fats and proteins. Carbohydrates are sugars and starches used by the body as fuel molecules and to store energy. Fats are compounds that store energy. Proteins are important components of cells and tissues and are large complex molecules composed of amino acids. (We will discuss carbohydrates, fats and proteins in more detail in Section 5 of this text.) Humans and other animals then eat plants and other animals to obtain energy required to maintain cellular activities. Homeostasis: The automatic tendency to maintain a relatively constant internal environment The body uses carbohydrates, fats and proteins consumed daily to provide the necessary energy to maintain cellular activity both at rest and during activity. Since all cells require energy, your bodies must have a way to convert carbohydrates, fats and protein into a biologically usable form of energy to fuel physical activity. The ability to run, jump and lift weights is contingent on and limited by your ability to transform food into biological energy. These physical abilities are contingent on thousands of chemical reactions that occur throughout our bodies all day long. Collectively these reactions are known as metabolism. These many chemical reactions occurring in our bodies must be regulated to maintain a balance. The body consists of trillions of cells, which are organized into tissues, organs, and systems. We will discuss this intricate organized system in more detail in Unit 2. The body’s components work together in a highly organized manner to maintain a balance. Metabolic activities are continually occurring in the trillions of cells in your body and must be carefully regulated to maintain a constant internal environment, or steady state. This steady state must be maintained regardless of your ever-changing external environment.This automatic tendency to maintain a relatively constant internal environment is called homeostasis.