Energy

Energy

Energy is a tough concept for students. You can’t hold it in your hand. You can’t see it. But it still exists.  If we were in a physics class, I would give this definition of energyThe capacity to do work or cause change.; the capacity to do work.  For our class, a better definition is that energy is held by moving electronsNegatively charged subatomic particles found in atoms.. They transfer and share it in this universe of matter. Therefore “work” is the process of expending the energy held by the ever-moving electrons.  The most important thing for us to remember is that energy is like a currency for bonding.  As we will learn, energy can be trapped in bonds or it can be released from bonds.  What I have here in these pictures are two examples of energy that we, as humans, can detect.  The lunchbox is full of chemical energy. Since it looks vegetarian, all that chemical energy was made by photosynthesis. Plants trapped solar energy into ATPThe energy currency of cells used for muscle contraction..  The other picture is energy produced by lightning.  Both of these items contain energy and are able to be perceived by humans.  As lightning strikes, you see the energy being given off as light. As the thunder claps, you hear the sound energy being given off as the rolls of thunder.

Forms and Types of Energy

Again, if we were in a physics class, we would concentrate on the types of energy: potential and kinetic.  But, here in A&P, we will constantly encounter the typical forms of energy.  So, the terms potential and kinetic refer to energy that is being stored. Potential is stored energy. Kinetic refers to energy that is actively being used.  Potential is the energy held by a stationary object. Kinetic is energy held by an object in motion.  But, remember, that there are things in this world that human can’t readily detect, like the movementA fundamental property of life involving motion of the body or its parts. of electrons.  So, even though a body might be dead, the electrons of the atomsThe smallest units of matter that retain the properties of an element. contained in that body remain in motion. Sparkzilla here is not alive, but Sparkzilla is a great example of potential and kinetic.  You wind Sparkzilla. The motion of your hand turning the crank generates kinetic energyEnergy of motion.. This kinetic energy is transformed into the potential energy stored in the wind-up mechanism within Sparkzilla.  Now, Sparkzilla contains potential energy. It is ready to lumber forth. It will emit sparks as soon as you switch the lever.  As Sparkzilla lumbers forth and emits sparks, they show us the kinetic energy of motion…and sparks.  If you play with Sparkzilla too much, the metal of his body starts to warm up.  As the potential energy turns to kinetic, some energy is lost.  This is true for everything in the universe.  When we change energy from one form to another, heat is always lost.

Now comes the more complicated part.  Let’s draw a terrible picture of your brain. Visualize a nerve coming from your brain. Then, think of the muscles in your little toe.  You eat.  You trap the chemical energy of your food into ATP in your cellsThe basic structural and functional units of life..  You use that energy to send electrical currents from your brain to the muscle in your big toe.  Your big toe muscle contracts displaying mechanical energy.  As the contraction happens and ATP is used, some heat is released. Changing forms of energy always results in some heat loss.  Always.

Endergonic Reactions

Endergonic reactions are reactions that trap energy.  These are anabolic reactions that build moleculesGroups of atoms bonded together..  Many of you might have assumed that from knowing that anabolic steroids help build muscle.  Anabolic reactions are also called synthesis reactions, a word that simply indicates the building or manufacturing of something.  Students usually pause at the word reduction and think that I’ve maybe made a mistake.  So, this word reduction does not mean to make smaller in this context.  Reduction means to gain electrons, to become more negative in charge.  Most reduction reactions are anabolic.  These types of reactions are abundant when you are a growing child.  As a child eats proteinsLarge molecules made of amino acids with various functions in the body., they are broken down into amino acidThe building blocks of proteins, consisting of an amino group, carboxyl group, and side chain. subunits.  Then, those amino acids are used to make proteins that the child needs to build muscle, bone, and other structures.

Exergonic Reactions

Exergonic reactions release the energy that endergonic reactions trapped into bonds.  These are break down reactions also known as decomposition of catabolismThe metabolic process that breaks down molecules to release energy..  As I burn this wood, the energy trapped in the bonds that the tree formed as it grew are broken. This releases energy as heat and light.  These reactions are primarily conducted by your digestive system. They mostly break down your food. These reactions also harvest the chemical energy trapped in the bonds.  Opposite to reduction reactions, these reactions are mostly oxidative. In these reactions, molecules give away electrons. They become more positively charged.