Transcript Anatomy & Physiology Ch. 2 Chemistry Comes Alive

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.
How are matter and energy
interrelated?
 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.
Properties of Matter
 Physical propertiescharacteristics 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.
Common Elements
in the Human Body
 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, cont.
 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 in the body, 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
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
Mixtures vs. Compounds
 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.
Ion formation
 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-
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
 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
Types of reactions
 Synthesis: A + B  AB
 Decomposition: AB A + B
 Displacement: AB + C  AC + B
 Redox: decomposition reactions that
break down food to produce energy
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
Factors affecting reaction rates
 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