anatomy & physiology ch. 2 part i “chemistry comes alive”
TRANSCRIPT
Anatomy & PhysiologyCh. 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, Ca2+ 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 H2O + NaCl reactants products
Chemical reactions
Synthesis: A + B ABDecomposition: AB A + BDisplacement: AB + C AC +
BRedox: 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