Download to accompany Holes` Essentials of Human Anatomy and Physiology

PowerPoint Presentation
to accompany
Hole’s Human Anatomy
and Physiology, 9/e
by
Shier, Butler, and Lewis
Chapter Two
Chemical Basis of Life
Chemistry and Biochemistry
• Chemistry considers the composition of
substances and how they change.
• The chemistry of living organisms is biological
chemistry or biochemistry.
• Biochemistry has been important in explaining
physiological processes and in improving
medicine.
Matter and Elements
• Matter is anything that has weight and takes up space.
• All matter is composed of elements.
• Elements exist is their pure form or in chemical
combinations called compounds.
• Elements are composed of atoms.
Atomic Structure
• Nucleus: center of the atom, containing
protons and neutrons
• Protons: positively charged particles
• Neutrons: particles which lack charge
• Electrons: very small, negatively charged
particles which encircle the nucleus
Figure 2.1
Isotopes
• Atomic number is the number of protons. It is the
same for all atoms of an element.
• Atomic weight is the number of protons and
neutrons.
• Atoms that have the same atomic number, but
different atomic weights are isotopes.
Stable and Radioactive Isotopes
• Isotopes that do not decompose are called
stable isotopes.
• Isotopes that have unstable nuclei that
decompose are called radioactive isotopes.
• Radioactive isotopes release energy or
particles until they reach a stable form.
Atomic Radiation
• Alpha radiation consists of particles from atomic
nuclei, two protons and two neutrons. These
particles are heavy, move slowly, and do not
penetrate matter.
Atomic Radiation
• Beta radiation consists of smaller electrons that
travel fast and penetrate matter.
• Gamma radiation is similar to X-radiation and is
the most penetrating of these forms.
Molecules
• Two or more atoms
combine to form a
molecule.
• Molecules are
distinctive from the
elements of which they
are composed.
• A molecular formula
illustrates the number
and type of atoms
found in a molecule.
Atomic Structure
• Atoms, such as Helium, whose outermost
electron shells are filled, have stable structures
and are chemically inactive or inert.
•Atoms with incompletely filled outer shells
tend to gain or lose electrons in ways that
empty or fill their outer shells and create a
stable structure.
Molecular Bonding
• Ions are formed when atoms gain or lose
electrons.
Molecular Bonding
• Ionic or
electrovalent
bonds are
formed by
the attraction
of oppositely
charged ions.
Molecular Bonding
• Covalent bonds are formed by the sharing of
electrons between atoms.
Molecular Bonding
• Hydrogen bonds are weak bonds between polar
molecules.
Polar Molecules
• Covalent bonds can be formed where the electrons
are not shared equally.
•This results in a polar molecule that has equal
numbers of protons and electrons, but one atom has
more that its share of electrons, becoming negative,
and one atom has less, becoming positive.
Polar Molecules
•These polar bonds occur where hydrogen
bonds to oxygen or nitrogen.
Chemical Reactions
•
•
•
•
Synthesis Reaction: A + B = AB
Decomposition Reaction: AB = A + B
Exchange Reaction: AB + CD = AD + CB
Reversible Reactions can proceed in either
direction
Reversible Reactions
• Many chemical reactions are reversible.
• The direction in which the reaction proceeds
depends on many factors such as:
- the proportions of products
- reactants
- amount of energy
- presence of catalysts
- molecules that influence the rate of reaction,
but are not consumed in the reaction.
Acids, Bases, Salts
• Polarity of water causes dissociation of salts,
releasing ions.
Acids, Bases, Salts
•
•
•
•
Electrolytes release ions in water.
Acids release hydrogen ions (H+).
Bases release ions that combine with H+.
Salts are formed by the reaction between an
acid and a base.
Acid and Base Concentrations
• Hydrogen ions concentrations are measured in
grams of ions per liter of solutions.
• The pH scale illustrates the hydrogen ions
concentration in a convenient form.
• Pure water ionizes only slightly and results in
equal numbers of hydrogen and hydroxyl ions,
pH 7, chemically neutral.
Hydrogen Ion Concentration
• Solutions with more hydrogen ions than
hydroxyl ions are acidic with ph values of
less than 7.
• Solutions with more hydroxyl ions than
hydrogen ions are basic with ph values of
greater than 7.
Body Fluid pH Changes
• Fluids in the human body function in a
narrow ph range.
• Blood ph of 7.5 to 7.8 is alkalosis, resulting
in agitation and dizziness.
• Blood ph of 7.0 to 7.3 is acidosis, resulting
in disorientation and fatigue.
Figure 2.9
Inorganic Substances
Water
Oxygen
Carbon Dioxide
Inorganic Salts
Water
• Water is the most abundant compound in living
material.
• It makes of 2/3 of the weight of an adult human.
Water
•Substances dissolve in water, making it possible
for metabolic reactions to occur.
• Water aids in transport of substances.
• Water absorbs and transports heat.
Oxygen and Carbon Dioxide
• Oxygen is used to release energy from
nutrient molecules.
• Carbon dioxide is produced as a waste
product when energy is released during
certain metabolic reactions.
Inorganic Salts
• Inorganic salts are the source of many important
ions, including Na+, Cl-, K+, Ca++, and many
others.
• These play a role in metabolic reactions and must
be maintained in appropriate concentrations.
• This is called electrolyte balance.
Organic Substances
• Organic molecules are carbon based molecules
containing hydrogen and often oxygen.
•Important groups of organic substances in cells
include carbohydrates, lipids, proteins, nucleic
acids.
Carbohydrates
• Carbohydrates: watersoluble molecules
containing carbon,
hydrogen, oxygen
• Sugars:
monosaccharides,
disaccharides
Carbohydrates
• Polysaccharides: built of simple sugars: starch,
fiber, glycogen
Lipids
• Three fatty acids combine with glycerol to form a
triglyceride.
Lipids
• Fatty acids can be saturated or unsaturated.
• Phospholipids contain two fatty acids and a phosphate
group.
Lipids
• Steroids are lipids composed of connected carbon rings,
ex: cholesterol.
Saturated vs. Unsaturated Fats
• A diet rich in saturated fat increases a person’s
risk of atherosclerosis.
• It is healthful to substitute unsaturated fats.
Saturated fats are found in fatty foods that are
solid at room temperature.
• Unsaturated fats are found in foods that are
liquid at room temperature.
Proteins
• Wide range of functions
• Chain of amino acids of varying lengths
• Amino acids contain a central carbon, an
amino group, a carboxyl group, and a side
chain (R group)
• Amino acids are linked in a peptide bond
joining the amino of one and carboxyl
group of another amino acid
Levels of Protein Structure
• Primary: amino acid sequence
• Secondary: coil or sheet formed by hydrogen
bonds between the amino acids
• Tertiary: three dimensional shape created by
hydrogen and covalent bonds
• Quarternary: association of several separate
protein chains
Figure 2.18
Nucleic Acids
•
•
•
•
RNA
ribose
single strand
aid in protein
synthesis
•
•
•
•
DNA
deoxyribose
double stranded
store genetic
information
Nucleic Acids
• Large, complex molecules
• Chains of nucleotides
• Nucleotides are composed of a sugar, a
phosphate group, and one of five nitrogen
bases
Figure 2.20a
Figure 2.20b