Download Chapter 2: Chemistry, Matter, and Life

Chapter 2
Chemistry, Matter, and Life
Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins
Key Terms
acid
chemistry
ion
salt
amino acid
colloid
isotope
solute
anion
compound
lipid
solution
aqueous
denaturation
molecule
solvent
atom
electrolyte
nucleotide
steroid
base
electron
neutron
substrate
buffer
element
pH
suspension
carbohydrate
enzyme
protein
valence
catalyst
glucose
proton
cation
glycogen
radioactive
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Chemistry
• Science that deals with matter’s composition and
properties
• Used to understand normal and abnormal body function
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Elements (cont.)
Matter
• The substances from which the universe is made
Elements
• All of the different types of matter
• Identified by names or chemical
symbols
• Also identified by number
• Described and organized in the
periodic table
11
Sodium
Na
22.99
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Elements (cont.)
Appendix 1 Periodic Table of the Elements
What is the symbol and number for carbon?
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Elements (cont.)
Table 2-1 Some Common Elements
Name
Oxygen
Symbol
O
Function
Part of water; needed to
metabolize nutrients for energy
Carbon
C
Hydrogen
H
Nitrogen
N
Calcium
Ca
Phosphorus
P
Potassium
K
Basis of all organic compounds;
component of carbon dioxide,
the gaseous byproduct of
metabolism
Part of water, participates in
energy metabolism; determines
the acidity of body fluids
Present in all proteins, ATP (the
energy-storing compound), and
nucleic acids (DNA and RNA)
Builds bones and teeth; needed
for muscle contraction, nerve
impulse conduction, and blood
clotting
Active ingredient in ATP; builds
bones and teeth; component of
cell membranes and nucleic
acids
Active in nerve impulse
conduction; muscle contraction
Sulfur
Sodium
S
Na
Iron
Fe
The elements are listed in decreasing order by weight in the body.
Part of many proteins
Active in water balance, nerve
impulse conduction, and muscle
contraction
Part of hemoglobin, the
compound that carries oxygen
in red blood cells
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Elements (cont.)
Living matter contains
26 of 92 natural
elements.
The body’s chemical composition by weight.
• 96% of body weight—
four elements
• 4% of body weight—
nine elements
• 0.1% of body
weight—13 elements
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Elements (cont.)
Atoms
• Smallest subunits of elements
• Cannot be broken down or changed by ordinary
chemical and physical means
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Elements (cont.)
Atomic Structure
• Nucleus
–
At atom’s center
–
Composed of
• Protons; positively charged
• Neutrons; not charged
• Electrons
–
Negatively charged
–
Orbit in energy levels around the nucleus
–
Determine atom’s chemical reactivity
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Elements (cont.)
Figure 2-2 The oxygen atom.
How does the proton number of this atom compare with
the electron number?
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Elements (cont.)
Atomic Number
8
Oxygen
• Equal to the number of protons in
an atom’s nucleus.
O
• Also represents the number of
electrons orbiting the nucleus.
16.00
• No two elements share the same
atomic number.
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Oxygen’s nucleus
contains eight
protons. Its
atomic number is
8.
Elements (cont.)
Energy Levels
• Regions around an atom’s nucleus where electrons orbit.
• Each region has space for a specific number of
electrons.
–
The first energy level has room for two electrons.
–
The second energy level has room for eight
electrons.
•
An atom is most stable when its energy levels are
filled with electrons.
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Elements (cont.)
Energy Levels (cont.)
Hydrogen Carbon
Total number of electrons
1
6
Number of electrons in first energy level
1
2
Number of electrons in second energy level
0
4
• Hydrogen has only one energy level with room for one
more electron.
• Carbon’s first energy level is full.
• Carbon’s second energy level has room for four more
electrons.
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Elements (cont.)
Energy Levels (cont.)
• An atom will form chemical bonds with other atoms to
fill its outermost energy level.
An atom will donate, accept, or share electrons to fill its
outermost energy level.
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Elements (cont.)
Figure 2-3 Examples of atoms.
How many electrons does oxygen need to complete its
outermost energy level? How does magnesium achieve a
stable outermost energy level?
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Elements (cont.)
Pop Quiz
2.1
Which element makes up the greatest percentage of
body weight?
A) Nitrogen
B) Oxygen
C) Potassium
D) Sodium
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Elements (cont.)
Pop Quiz Answer
2.1
Which element makes up the greatest percentage of
body weight?
A) Nitrogen
B) Oxygen
C) Potassium
D) Sodium
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Elements (cont.)
Pop Quiz
2.2
The atomic number of iron is 26. How many protons
does iron have?
A) 13
B) 26
C) 39
D) 52
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Elements (cont.)
Pop Quiz Answer
2.2
The atomic number of iron is 26. How many protons
does iron have?
A) 13
B) 26
C) 39
D) 52
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Chemical Bonds (cont.)
• An atom forms chemical bonds with other atoms to fill
its outermost energy level with electrons.
– Electrons may be transferred between atoms.
– Electrons may be shared between atoms.
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Chemical Bonds (cont.)
Valence
The number of bonds an atom needs to fill its outermost
energy level.
Example
• A carbon atom has six electrons.
• Its outermost energy level contains four
electrons.
• It needs four more electrons to fill its
outermost energy level.
• Carbon’s valence is 4.
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6
Carbon
C
12.01
Chemical Bonds (cont.)
Ionic Bonds
• Form when one atom transfers electrons
to another atom
– The atom that donates an electron
becomes a positively charged cation.
Na+
– The atom that accepts an electron
becomes a negatively charged anion.
Cl–
– The ionic bond is the attraction
between oppositely charged ions.
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Na+
Cl–
Chemical Bonds (cont.)
Figure 2-4 Ionic bonding.
How many electrons are in the
outermost energy level of a
sodium atom? Of a chlorine atom?
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Chemical Bonds (cont.)
Electrolytes
• Compounds that separate into ions in solution
• Term also used to refer to the ions themselves
Example
Sodium chloride (NaCl) is an electrolyte.
When NaCl is added to water, it separates into Na+ and Cl− ions.
Both Na+ and Cl− ions are electrolytes.
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Chemical Bonds (cont.)
Ions in the Body
• Ions play important physiologic roles in body fluid.
Examples
Ion
Functions
Ca2+
Blood clotting, muscle contraction
HCO3−
pH regulation
• Homeostasis maintains proper ion concentration.
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Chemical Bonds (cont.)
Ions in the Body (cont.)
• Ions conduct electric currents in body fluid.
• Measurement of a tissue’s electrical activity is used to
diagnose disease.
Examples
Electrocardiogram
A record of the heart’s electrical activity
Electroencephalogram
A record of the brain’s electrical activity
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Chemical Bonds (cont.)
Covalent Bonds
•
Form when two atoms share electrons
•
The most common chemical bond in the body
•
Types:
– Nonpolar covalent bond
• Electrons are shared equally.
– Polar covalent bond
• Electrons are shared unequally.
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Chemical Bonds (cont.)
Figure 2-5 A nonpolar covalent bond.
How many electrons are needed to complete the energy
level of each hydrogen atom?
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Chemical Bonds (cont.)
Figure 2-6 Formation of water.
How many hydrogen atoms bond with an oxygen atom
to form water?
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Chemical Bonds (cont.)
Molecules
• Chemicals composed of two or more atoms held
together with covalent bonds
–
Examples: O2, H2O
Compounds
• Chemicals composed of two or more different atoms
held together by ionic or covalent bonds
–
Examples: NaCl, H2O, CO2
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Chemical Bonds (cont.)
Pop Quiz
2.3
What bond forms between two atoms that share
their electrons equally?
A) Hydrogen bond
B) Ionic bond
C) Nonpolar bond
D) Polar bond
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Chemical Bonds (cont.)
Pop Quiz Answer
2.3
What bond forms between two atoms that share
their electrons equally?
A) Hydrogen bond
B) Ionic bond
C) Nonpolar bond
D) Polar bond
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Chemical Bonds (cont.)
Pop Quiz
2.4
Which term best describes the sodium ion (Na+)?
A) Anion
B) Atom
C) Electrolyte
D) Element
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Chemical Bonds (cont.)
Pop Quiz Answer
2.4
Which term best describes the sodium ion (Na+)?
A) Anion
B) Atom
C) Electrolyte
D) Element
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Chemical Bonds (cont.)
Pop Quiz
2.5
Which chemical is NOT a compound?
A) CO2
B) H2O
C) NaCl
D) O2
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Chemical Bonds (cont.)
Pop Quiz Answer
2.5
Which chemical is NOT a compound?
A) CO2
B) H2O
C) NaCl
D) O2
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Mixtures (cont.)
Table 2-2 Mixtures
Type
Definition
Example
Solution
Homogeneous mixture formed
when one substance (solute)
dissolves in another (solvent)
Table salt (NaCl)
dissolved in water;
table sugar
(sucrose) dissolved
in water
Suspension
Heterogeneous mixture in which
one substance is dispersed in
another but will settle out unless
constantly mixed
Red blood cells in
blood plasma; milk
of magnesia
Colloid
Heterogeneous mixture in which
the suspended particles remain
evenly distributed based on the
small size and opposing charges
of the particles
Blood plasma;
cytosol
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Mixtures (cont.)
The Importance of Water
• Most abundant compound in body
• Critical in all physiologic processes
• Deficiency (dehydration) threatens health
• Universal solvent
• Stable liquid at ordinary temperatures
• Participates in body’s chemical reactions
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Mixtures (cont.)
Pop Quiz
2.6
Which term describes a substance that dissolves
another substance?
A) Mixture
B) Solute
C) Solution
D) Solvent
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Mixtures (cont.)
Pop Quiz Answer
2.6
Which term describes a substance that dissolves
another substance?
A) Mixture
B) Solute
C) Solution
D) Solvent
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Mixtures (cont.)
Pop Quiz
2.7
Which substance is termed the universal solvent?
A) An acid
B) A base
C) Carbon
D) Water
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Mixtures (cont.)
Pop Quiz Answer
2.7
Which substance is termed the universal solvent?
A) An acid
B) A base
C) Carbon
D) Water
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Acids, Bases, and Salts (cont.)
Acid
• A substance that releases hydrogen ions
HCl  H+ + Cl−
Base
• A substance that releases hydroxide ions and accepts
hydrogen ions
NaOH  Na+ + OH−
Salt
• A substance formed by a reaction between an acid and a
base
HCl + NaOH  NaCl + H2O
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Acids, Bases, and Salts (cont.)
The pH Scale
• Measures the relative concentrations of hydrogen and
hydroxide ions in a solution.
– Scale from 0 (most acidic) to 14 (most basic).
– Each unit represents a 10-fold change.
• Normal body fluid pH range is between 7.35 and 7.45.
– Acidosis: Body fluid pH less than 7.35
– Alkalosis: Body fluid pH greater than 7.45
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Acids, Bases, and Salts (cont.)
Figure 2-7 The pH scale.
What happens to the amount of hydroxide ion (OH–)
present in a solution when the amount of hydrogen ion
(H+) increases?
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Acids, Bases, and Salts (cont.)
Buffers
• Chemicals that prevent sharp changes in H+
concentration
• Are important in maintaining a relatively constant pH in
body fluids
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Acids, Bases, and Salts (cont.)
Pop Quiz
2.8
Which substance always accepts hydrogen ions?
A) An acid
B) A base
C) A buffer
D) A salt
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Acids, Bases, and Salts (cont.)
Pop Quiz Answer
2.8
Which substance always accepts hydrogen ions?
A) An acid
B) A base
C) A buffer
D) A salt
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Acids, Bases, and Salts (cont.)
Pop Quiz
2.9
Which substance always has a pH below 7?
A) An acid
B) A base
C) A buffer
D) A salt
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Acids, Bases, and Salts (cont.)
Pop Quiz Answer
2.9
Which substance always has a pH below 7?
A) An acid
B) A base
C) A buffer
D) A salt
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Acids, Bases, and Salts (cont.)
Pop Quiz
2.10 Which substance is most important in maintaining a
relatively constant pH in body fluids?
A) An acid
B) A base
C) A buffer
D) A salt
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Acids, Bases, and Salts (cont.)
Pop Quiz Answer
2.10 Which substance is most important in maintaining a
relatively constant pH in body fluids?
A) An acid
B) A base
C) A buffer
D) A salt
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Isotopes and Radioactivity (cont.)
Isotopes
• Forms of an element that have the same atomic number
but different atomic weight
–
Different atomic weight because of a different
number of neutrons
Examples
Isotope
Proton
Number
Neutron
Number
Atomic Weight
Carbon-12
6
6
12
Carbon-13
6
7
13
Carbon-14
6
8
14
• May be stable or unstable (radioactive)
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Isotopes and Radioactivity (cont.)
Radioactivity
• Emission of atomic particles from an isotope
Use of Radioactive Isotopes
• Used in the treatment of cancer
–
Radiation penetrates and destroys tumor cells.
• Used in diagnosis
–
Radioactive elements can be administered and
detected internally to identify abnormalities—these
are called tracers. Example: Radioactive iodine used
to diagnose thyroid problems.
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Isotopes and Radioactivity (cont.)
Pop Quiz
2.11 A form of an element that differs in its atomic
weight from other forms of that same element is
a(n) ____________.
A) Compound
B) Ion
C) Isotope
D) Molecule
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Isotopes and Radioactivity (cont.)
Pop Quiz Answer
2.11 A form of an element that differs in its atomic
weight from other forms of that same element is
a(n) ____________.
A) Compound
B) Ion
C) Isotope
D) Molecule
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Organic Compounds (cont.)
Chemistry of Living Matter
• Hydrogen, oxygen, carbon, and nitrogen make up 96%
of body weight.
Organic Compounds
• Chemical compounds found in living things
• Built on the element carbon
• Main types
–
Carbohydrates
–
Lipids
–
Proteins
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Organic Compounds (cont.)
Carbohydrates
• Monosaccharides
–
Basic units of carbohydrates
• Disaccharides
–
Two monosaccharides linked together
• Polysaccharides
–
Many monosaccharides linked together
Carbohydrate
Examples
Monosaccharide
Glucose
Disaccharide
Sucrose and lactose
Polysaccharide
Glycogen and starch
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Organic Compounds (cont.)
Figure 2-8 Examples of carbohydrates.
What are the building blocks (monomers) of disaccharides
and polysaccharides?
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Organic Compounds (cont.)
Lipids (Fats)
• Triglycerides
–
Simple fat composed of glycerol and three fatty acids
• Phospholipids
–
Complex lipid containing phosphorus
• Steroids
–
Contain rings of carbon atoms (e.g., cholesterol)
Lipid
Functions
Triglyceride
Insulates body, protects organs, stores energy
Phospholipid
Main component of cell membranes
Steroid
Regulate body function (e.g., cortisol, sex hormones)
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Organic Compounds (cont.)
Figure 2-9 Lipids.
How many carbon atoms
are in glycerol?
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Organic Compounds (cont.)
Proteins
• Contain nitrogen (and sometimes sulfur or phosphorus).
• Found as structural materials and metabolically active
compounds.
• Composed of chains of amino acids held together by
peptide bonds.
• The overall three-dimensional shape of a protein is
caused by folding.
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Organic Compounds (cont.)
Figure 2-10 Proteins.
What part of an amino acid contains nitrogen?
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Organic Compounds (cont.)
Enzymes
• Are proteins that speed up (catalyze) chemical reactions
• Work on specific substrates
• Are not used up or changed during a chemical reaction
• Work via the “lock-and-key” mechanism
• Denature in harsh conditions (e.g., extremes of
temperature or pH)
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Organic Compounds (cont.)
Figure 2-11 Diagram of enzyme action.
How does the shape of the enzyme before the reaction
compare with its shape after the reaction?
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Organic Compounds (cont.)
Nucleotides
• Composed of:
–
A nitrogenous base
–
A sugar (usually ribose or deoxyribose)
–
A phosphate group
• Building blocks of DNA and RNA
• One type is a component of ATP
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Organic Compounds (cont.)
Figure 2-12 Nucleotides.
What does the prefix tri- in adenosine triphosphate mean?
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Organic Compounds (cont.)
Pop Quiz
2.12 Which element is the basis of organic chemistry?
A) Carbon
B) Hydrogen
C) Nitrogen
D) Oxygen
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Organic Compounds (cont.)
Pop Quiz Answer
2.12 Which element is the basis of organic chemistry?
A) Carbon
B) Hydrogen
C) Nitrogen
D) Oxygen
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Organic Compounds (cont.)
Pop Quiz
2.13 Which organic compound catalyzes metabolic
reactions?
A) Carbohydrate
B) Enzyme
C) Lipid
D) Nucleotide
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Organic Compounds (cont.)
Pop Quiz Answer
2.13 Which organic compound catalyzes metabolic
reactions?
A) Carbohydrate
B) Enzyme
C) Lipid
D) Nucleotide
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Organic Compounds (cont.)
Pop Quiz
2.14 Which organic compound is used to store genetic
information?
A) Carbohydrate
B) Enzyme
C) Lipid
D) Nucleotide
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Organic Compounds (cont.)
Pop Quiz Answer
2.14 Which organic compound is used to store genetic
information?
A) Carbohydrate
B) Enzyme
C) Lipid
D) Nucleotide
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Organic Compounds (cont.)
Pop Quiz
2.15 A substance that has a name ending in -ase is most
likely a(n)?
A) Carbohydrate
B) Enzyme
C) Lipid
D) Nucleotide
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Organic Compounds (cont.)
Pop Quiz Answer
2.15 A substance that has a name ending in -ase is most
likely a(n)?
A) Carbohydrate
B) Enzyme
C) Lipid
D) Nucleotide
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Case Study
Learning Objective
15. Use the case study to discuss the
importance of regulating body
fluid quantity and composition.
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Case Study (cont.)
Margaret’s Case: Chemistry’s Role in Health Science
• Some terms that illustrate the importance of body fluid
quantity and composition:
–
Dehydration
–
Hematocrit
–
Hypernatremia
–
Hypotension
–
Tachycardia
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Word Anatomy
Learning Objective
16. Show how word parts are used to build words related
to chemistry, matter, and life.
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Word Anatomy (cont.)
Word Part
Meaning
Example
Chemical Bonds
co-
together
Covalent bonds form when atoms share
electrons.
Solutions and Suspensions
aqu/e
water
In an aqueous solution, water is solvent.
heter/o-
different
Heterogeneous solutions are different
(not uniform) throughout.
hom/o-
same
Homogeneous mixtures are the same
throughout.
hydr/o
water
Dehydration is a deficiency of water.
phil
to like
Hydrophilic substances “like” water—
they mix with or dissolve it.
phobia
to fear
Hydrophobic substances “fear” water—
they repel and do not dissolve it.
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Word Anatomy (cont.)
Word Part
Meaning
Example
Organic Compounds
-ase
suffix used in naming
enzymes
A lipase is an enzyme that acts on lipids.
de-
remove
Denaturation of a protein removes its ability
to function (changes its nature).
di-
twice, double
A disaccharide consists of two simple sugars.
glyc/o-
glucose, sweet
Glycogen is a storage form of glucose. It
breaks down to release glucose.
mon/o-
one
In a monosaccharide, “mono-” refers to one.
poly-
many
A polysaccharide consists of many simple
sugars.
sacchar/o
sugar
A monosaccharide consists of one simple
sugar.
tri-
three
Triglycerides have one fatty acid attached to
each of three carbon atoms.
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