Chapter 2, Lesson 3: Energy and Chemical Reactions

Flashcards from Chapter 2, Lesson 3 of McGraw Hill Anatomy and Physiology, Ninth Edition, by Kenneth S. Saladin.

Energy

The capacity to do work; all body activities are work

Potential energy

Energy stored in an object but not currently doing work (e.g. water behind a dam)

Chemical energy

Potential energy in molecular bonds

Free energy

Potential energy available in a system to do useful work

Kinetic energy

The energy of motion which is doing work (e.g. water flowing through a dam)

Heat

The kinetic energy of molecular motion

Electromagnetic energy

The kinetic energy of moving packets of radiation called photons

Chemical reaction

Process in which a covalent or ionic bond is formed or broken

Chemical equation

Symbolizes the course of a chemical reaction; reactions on the left → products on the right

Decomposition reactions

Large molecule breaks down into two or more smaller ones; AB → A + B

Synthesis reactions

Two or more smaller molecules combine to form a larger one; A + B → AB

Exchange reactions

Two molecules exchange atoms or a group of atoms; AB + CD → ABCD → AC + BD

Reversible reactions

Reactions that can reverse under different circumstances; symbolized with a double-headed arrow

Law of mass action

Direction of reaction determined by relative abundance (quantity) of either side of equation

Increasing reaction rate causes

Rising temperature, concentrated reactants, catalysts like enzymes to lower the reaction energy

Metabolism

All chemical reactions of the body

Catabolism

Energy releasing (exergonic) decomposition reactions that break covalent bonds and produce smaller molecules

Anabolic reactions

Energy storing (endergonic) synthesis reactions that require energy input (e.g. production of fat)

Oxidation

A chemical reaction in which a molecule gives up electrons and releases energy

Reduction

Any chemical reaction in which a molecule gains electrons or energy

Oxidizing agent or reduced molecule

The molecule that accepts the electrons; oxygen is often the acceptor

Reducing agent or oxidized molecule

The molecule that donates electrons

Oxidation-reduction (redox) reactions

Oxidation of one molecule (giving away electrons) is always accompanied by reduction of another (gaining electrons); electrons are transferred as hydrogen atoms