1. PowerPoint Lecture Outlines to accompany
Hole’s Human
Anatomy and Physiology
Tenth Edition
Shier w Butler w Lewis
Chapter 2
2-1
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. Chapter 2 Chemical Basis of Life
Why study chemistry in an Anatomy and Physiology class?
- body functions depend on cellular functions
- cellular functions result from chemical changes
- biochemistry helps to explain physiological processes, and develop new drugs and methods for treating diseases
2-2

3. Structure of Matter
Matter – anything that takes up space and has weight; composed of elements
Elements – composed of chemically identical atoms
bulk elements – required by the body in large amounts
trace elements – required by the body in small amounts
Atoms – smallest particle of an element
2-3

4. Atomic Structure Atoms - composed of subatomic particles:
protons – carry a positive charge
neutrons – carry no electrical charge
electrons – carry a negative charge
Nucleus
central part of atom
composed of protons and neutrons
electrons move around the nucleus
2-4

5. Atomic Number and Atomic Weight
number of protons in the nucleus of one atom
each element has a unique atomic number
equals the number of electrons in the atom
Atomic Weight
the number of protons plus the number of neutrons in one atom
electrons do not contribute to the weight of the atom
2-5

6. Isotopes
Isotopes
atoms with the same atomic numbers but with different atomic weights
atoms with the same number of protons and electrons but a different number of neutrons
oxygen often forms isotopes (O16, O17, O18)
unstable isotopes are radioactive; they emit subatomic particles
2-6

7. Molecules and Compounds
Molecules – particle formed when two or more atoms chemically combine
Compound – particle formed when two or more atoms of different elements chemically combine
Molecular formulas – depict the elements present and the number of each atom present in the molecule
H C6H12O H2O
2-7

8. Electrons
found in regions of space called electron shells (energy shells)
each shell can hold a limited number of electrons
for atoms with atomic numbers of 18 or less, the following rules apply:
the first shell can hold up to 2 electrons
the second shell can hold up to 8 electrons
the third shell can hold up to 8 electrons
lower shells are filled first
if the outermost shell is full, the atom is stable
2-8

9. Ions Ion an atom that has gained or lost an electron(s)
an electrically charged atom
atoms form ions to become stable
Cation
a positively charged ion
formed when an atom loses an electron(s)
Anion
a negatively charged ion
formed when an atom gains an electron(s)
2-9

10. Ionic Bond Ionic Bond an attraction between a cation and an anion
formed when electrons are transferred from one atom to another atom
2-10

11. Covalent Bond Formed when atoms share electrons
Hydrogen atoms form single bonds
Oxygen atoms form two bonds
Nitrogen atoms form three bonds
Carbon atoms form four bonds
H ― H
O = O
N ≡ N
O = C = O
2-11

12. Structural Formula
Structural formulas show how atoms bond and are arranged in various molecules
2-12

13. Polar Molecules Polar Molecule
molecule with a slightly negative end and a slightly positive end
results when electrons are not shared equally in covalent bonds
water is an important polar molecule
2-13

14. Hydrogen Bonds Hydrogen Bond
a weak attraction between the positive end of one polar molecule and the negative end of another polar molecule
formed between water molecules
important for protein and nucleic acid structure
2-14

15. Chemical Reactions
Chemical reactions occur when chemical bonds form or break among atoms, ions, or molecules
Reactants are substances being changed by the chemical reaction
Products are substances formed at the end of the chemical reaction
NaCl ’ Na+ + Cl-
Reactant
Products
2-15

16. Types of Chemical Reactions
Synthesis Reaction – chemical bonds are formed
A + B ’ AB
Decomposition Reaction – chemical bonds are broken
AB ’ A + B
Exchange Reaction – chemical bonds are broken and formed
AB + CD ’ AD + CB
Reversible Reaction – the products can change back to the reactants
A + B n AB
2-16

17. Acids, Bases, and Salts
Electrolytes – substances that release ions in water
NaCl  Na+ + Cl-
Acids – electrolytes that release hydrogen ions in water
HCl  H+ + Cl-
Bases – substances that release ions that can combine with hydrogen ions
NaOH  Na+ + OH-
Salts – electrolytes formed by the reaction between an acid and a base
HCl + NaOH  H2O + NaCl
2-17

18. Acid and Base Concentrations
pH scale - indicates the
concentration of hydrogen ions in
solution
Neutral – pH 7; indicates equal concentrations of H+ and OH-
Acidic – pH less than 7; indicates a greater concentration of H+
Basic or alkaline – pH greater than 7;
indicates a greater concentration of OH-
2-18

19. Organic Versus Inorganic
Organic molecules
contain C and H
usually larger than inorganic molecules
dissolve in water and organic liquids
carbohydrates, proteins, lipids, and nucleic acids
Inorganic molecules
generally do not contain C
usually smaller than organic molecules
usually dissolve in water or react with water to release ions
water, oxygen, carbon dioxide, and inorganic salts
2-19

20. Inorganic Substances Water most abundant compound in living material
two-thirds of the weight of an adult human
major component of all body fluids
medium for most metabolic reactions
important role in transporting chemicals in the body
can absorb and transport heat
Oxygen (O2)
used by organelles to release energy from nutrients
necessary for survival
2-20

21. Inorganic Substances Carbon dioxide (CO2)
waste product released during metabolic reactions
must be removed from the body
Inorganic salts
abundant in body fluids
sources of necessary ions (Na+, Cl-, K+, Ca2+, etc.)
play important roles in metabolic processes
2-21

22. Organic Substances Carbohydrates
provide energy to cells
supply materials to build cell structures
water-soluble
contain C, H, and O
ratio of H to O close to 2:1 (C6H12O6)
monosaccharides – glucose, fructose
disaccharides – sucrose, lactose
polysaccharides – glycogen, cellulose
2-22

23. Organic Substances Carbohydrates
2-23

24. Organic Substances Lipids
soluble in organic solvents
fats (triglycerides)
used primarily for energy
contain C, H, and O but less O than carbohydrates (C57H110O6)
building blocks are 1 glycerol and 3 fatty acids per molecule
saturated and unsaturated
2-24

25. Organic Substances Lipids
phospholipids
building blocks are 1 glycerol, 2 fatty acids, and 1 phosphate per molecule
hydrophilic and hydrophobic
major component of cell membranes
2-25

26. Organic Substances Lipids
steroids
connected rings of carbon
component of cell membrane
used to synthesize hormones
cholesterol
2-26

27. Organic Substances Proteins
structural material
energy source
hormones
receptors
enzymes
antibodies
amino acids held together with peptide bonds
building blocks are amino acids
2-27

28. Organic Substances Proteins
Four Levels of Structure
2-28

29. Organic Substances Nucleic Acids
constitute genes
play role in protein synthesis
building blocks are nucleotides
DNA (deoxyribonucleic acid) – double polynucleotide
RNA (ribonucleic acid) – single polynucleotide
2-29

30. Organic Substances Nucleic Acids
2-30

31. Clinical Applications
Radioactive Isotopes Reveal Physiology
injected into the body
different types taken up by different organs
can be detected in the body using a scintillation counter
can be used to destroy specific tissues
commonly used
iodine-131 for thyroid function
thallium-201 for heart function
gallium-67 and cobalt-60 for cancer
others used to assess kidney functions, measure hormone levels and bone density changes
2-31