Anatomy & Physiology Ch. 2 Part I “Chemistry Comes Alive”

States of Matter  Solids- definite shape and volume, such as bones and teeth  Liquid- definite volume, but takes the shape of the container, such as blood plasma and urine.  Gas- no definite shape or volume, such as oxygen and carbon dioxide

Changes in Matter  Chemical change-alters the identity of the material, creating a new substance. Example: Digestion of food  Physical change-just changes the form of the substance, but not its identity Example: Breaking a bone

Forms of Energy  Energy exists in two forms, each transformable to the other.  Kinetic energy- energy of movement, from atoms to larger objects  Potential energy- stored energy that can be used later

Forms of energy used by the body  Chemical energy- energy stored in the bonds of chemical substances, such as food molecules. Converted to ATP that is used by cells.  Electrical energy-energy created by the movement of charged particles. Nerve impulses are electrical energy

Forms of energy, cont.  Mechanical energy-energy directly involved in movement, such as walking  Radiant (electromagnetic) energy- energy that travels in waves. Light rays stimulate the retina for vision and the body to make vitamin D.

 Energy does not have mass and does not take up space.  Energy is measured by its effect on matter.  Both matter and energy are conserved—they cannot be created or destroyed, but can change form  Energy is never “lost” when it changes form, but may become unusable. How are matter and energy interrelated?

Properties of Matter  Physical properties- characteristics of a substance that can be detected with the senses. Ex) color, texture, boiling point  Chemical properties-pertain to the way atoms interact with other atoms Ex) reactivity, flammability

Basic atomic structure  Atoms are made up of a nucleus, consisting of protons (+) and neutrons (0).  Surrounding the nucleus are negatively charged electrons traveling in orbitals.  Since atoms have the same number of protons and electrons, they are electrically neutral.

 Oxygen (O)- Major component of organic molecules. Gas is needed for cellular respiration (ATP production)  Carbon (C)- Found in all organic molecules, including carbohydrates, proteins, lipids, and nucleic acids  Hydrogen (H)- Component of all organic compounds, and as H+ it influences the pH of body fluids  Nitrogen (N)- Important in the structure of protein and nucleic acids Common Elements in the Human Body

 Calcium (Ca)- Calcium phosphate forms bones and teeth, Ca 2+ is needed muscle contraction, nerve impulses, and blood clotting  Phosphorus (P)- found in bones, teeth, nucleic acids and ATP  Potassium (K)- K + is the major positive ion in cells, needed for nerve impulses and muscle contraction  Sulfur (S)- found in the amino acid cysteine, involved in protein structure  Sodium (Na)- major cation found in extracellular fluids, important for water balance, conduction of nerve impulses, and muscle contraction Common elements, cont.

 Chlorine (Cl)- the most abundant anion in extracellular fluids  Magnesium (Mg)- present in bone, important cofactor in metabolic reactions  Iodine (I)- needed to produce functional thyroid hormones  Iron (Fe)- component of hemoglobin and some enzymes  ** Carbon, hydrogen, oxygen, and nitrogen make up 96% of body weight Common elements in the body, cont.

Isotopes  Isotopes are atoms of the same element that have a different number of neutrons, resulting in different atomic masses.  Radioisotopes are radioactive, producing radiation that can be detected by scanners.  Radioisotopes are valuable diagnostic tools for biological research and medicine. They can be used for diagnosing and treating cancers, and for PET scans.

Compounds  Elements and compounds are pure substances.  Elements are composed of the same type of atoms. Ex) O, N, Cl, Na  Compounds are formed when two or more atoms are chemically combined in definite proportions. Ex) NaCl

Mixtures  Mixtures are made of components that are physically intermixed, but not chemically combined  There are three basic types of mixtures: solutions, colloids, and suspensions

Solutions  Solutions are homogeneous mixtures of gases, liquids, or solids.  Examples: air we breathe, seawater, IV fluids  The substance present in the greatest amount is the solvent.  Substances present in smaller amounts are called solutes.  True solutions are described in terms of their concentration, such as molarity or % composition.

Colloids  Colloids, or emulsions, are heterogeneous mixtures with particles that do not settle out.  Colloids scatter light, and some can undergo sol-gel transformations, changing reversibly from liquid to more solid (gel) state.  Examples include gelatin and cytoplasm.

Suspensions  Suspensions are heterogeneous mixtures with large, often visible solutes that are undissolved and may settle out.  An example is blood—living blood cells are suspended in blood plasma

 1) No chemical bonding occurs within the components of a mixture. Atoms in a molecule of a compound are chemically bonded  2) The components of a mixture can usually be separated by physical means, such as by filtering, evaporation, or centrifuging. Compounds can only be separated by breaking chemical bonds between the atoms.  3) Compounds are pure substances and are always homogeneous in nature. Mixtures may be homogeneous or heterogeneous. Mixtures vs. Compounds

 Valence electrons are the e- found in the outer energy shell of an atom. These e- are lost, gained, or shared during chemical reactions, and are the electrons involved in forming chemical bonds.  If an atom loses e-, a positive ion is formed (cation). Ex) Na +  If an atom gains e-, a negative ion forms (anion). Ex) Cl - Ion formation

Chemical bonds  Ionic bonds- form when electrons are transferred from one atom to another. Can form crystals Ex) NaCl is an ionic compound  Covalent bonds- form when electrons are shared between atoms. Equal sharing = nonpolar, unequal sharing=polar Ex) Water (polar), cholesterol (nonpolar)  Organic macromolecules such as carbohydrates, proteins, lipids, and nucleic acids are formed by covalent bonds between carbon atoms.

Chemical bonds, cont.  Hydrogen bonds-form when hydrogen is bonded to a more electronegative atom like oxygen or nitrogen. Intramolecular bonds  Water forms hydrogen bonds between molecules, making it cohesive and slow to change temperature

 Chemical reactions occur when chemical bonds are formed, rearranged, or broken.  Chemical reactions are represented by chemical equations.  Compounds are represented by formulas, with the reactants on the left side of the equation and products on the right. NaOH + HCl  H 2 O + NaCl reactants products Chemical reactions

 Synthesis: A + B  AB  Decomposition: AB  A + B  Displacement: AB + C  AC + B  Redox: decomposition reactions that break down food to produce energy Types of reactions

Exergonic vs. Endergonic Reactions  Exergonic reactions release energy. Includes catabolic and oxidative processes.  Ex) Digestion of food, Cellullar respiration  Endergonic reactions absorb energy. Includes anabolic/synthesis reactions that store energy.  Ex) Protein synthesis, Photosynthesis

 Temperature- increasing temperature causes molecules to move faster, speeding up the reaction.  Size of particles- smaller particles move faster and react more rapidly than large ones.  Concentration of reactants- High concentration of reactants speeds up the process  Presence of catalysts- speed up the reaction rate. Ex) enzymes Factors affecting reaction rates