Human Body

Chapter 2Basic Chemistry

Chemistry in the Human Body

• The food that we eat is composed of chemicals

• The medicines that we take are composed of chemicals

• The entire body is composed of chemicals• Chemical rxns underlie all body processes

Concepts of Matter and Energy

• Matter= the “stuff” of the universe• Anything that occupies space and has mass• Matter exists in solid, liquid, and gaseous state– Ex. Solids= bones and teeth– Ex. Liquids= blood plasma and interstitial fluid– Ex. Gases= air that we breathe

Changes in Matter

• Physical Changes- do not alter the basic nature of a substance.– Ice melting to become water, cutting food into

smaller pieces

Changes in Matter

• Chemical Changes- do alter the composition of a substance– Fermenting grapes to make wine, digestion of

food

Energy

• No mass and does not take up space• It can only be measured by its effects on

matter• The ability to do work or to put matter into

motion

Types of Energy

• Kinetic Energy-when energy is actually doing work

• Potential Energy- inactive or stored energy

• All forms of energy exhibit both kinetic and potential work capacites.

Forms of Energy

1. Chemical Energy- energy that is stored in the bonds of chemical substances

**All body activities are “run” by the chemical energy harvested from the foods we eat.

Forms of Energy

2. Electrical Energy-energy that results from the movement of charged particles.

-An electrical current is generated when charged particles (ions) move across cell membranes

Forms of Energy

3. Mechanical Energy- is directly involved in moving matter.

-As the muscles in your legs shorten, they pull on your bones, causing your limbs to move.

Forms of Energy

4. Radiant Energy- energy that travels in waves, energy of the electromagnetic spectrum.

-includes x-rays, ultraviolet waves

-Ultraviolent waves are responsible for the suntan we get at the beach but also stimulate our bodies to make vitamin D.

Energy Form Conversions

• Ex. The chemical of foods is trapped in the bonds of high energy molecules called ATPs.

• ATPs energy can be transformed into the electrical energy of a nerve impulse or mechanical energy of shortening muscles.

Energy Form Conversions

• Energy conversions are very inefficient.• Some initial energy is lost as heat(ex. Light

bulb is losing some energy as heat and not all of it is used as light energy.

• Humans have a high body temp. that influences the rxns in the body

Composition of Matter

• All matter is composed of a limited number of fundamental substances called ELEMENTS.

• Element-a unique substance that cannot be broken down or decomposed into simpler substances by ordinary chemical methods.

Composition of Matter

• A complete listing of elements appears in the Periodic Table.

• The most abundant elements in the Human Body are listed in Table 2.1.

• The building block of matter=ATOM• Atoms of each element will differ from those

of all the other atoms.

Composition of Matter

• Atomic Symbol=a one or two letter chemical shorthand that is used to identify each element.– Ex. O=oxygen, Ca=Calcium, Ag=Silver(sometimes the symbol is taken from the Latin

name of the elements)

Atomic Structure

Subatomic Particles1) Protons-are found in the nucleus of the atom

and carry a positive charge.2) Neutrons- are found in the nucleus of the

atom and carry a neutral charge.3) Electrons- are found in the energy shells

orbiting the nucleus and carry a negative charge.

Atomic Structure

• Atomic Number= the number of protons

• Atomic Mass Number= the number of the protons + the number of neutrons

Isotopes

• Almost all elements have at least two or more structural variations.

• Isotopes have the same number of protons and electrons but different numbers of neutrons.

• Isotopes of the same element will have the same atomic number but different mass numbers.

Molecules

• A molecule is formed when two or more atoms are combined chemically.– Ex. O+O=O2

• When two or more atoms of different elements join together a Compound is formed.– Ex. H+ O= H2O

• Occur whenever atoms combine with or dissociate from other atoms.

• A chemical bond is not a physical structure but an energy relationship that involves the interactions between the electrons of the reacting elements.

Chemical Rxns

Chemical Bonds

• Ionic Bonds-form when electrons are completely transferred from one atom to another.

• Atoms are neutral but when they gain or lose electrons they become charged.

• Ions=charged particles

Chemical Bonds

• Covalent Bonds- when electrons are shared between atoms.

**The point of bonds is for atoms to become stable***

Hydrogen Bonds

• Extremely weak bonds formed when a Hydrogen atom gives an electron to another element.

Patterns of Chemical Rxns

• Chemical rxns involve the making or breaking of bonds between atoms.

Three Types of Rxns1) Synthesis Rxns2) Decomposition Rxns3) Exchange Rxns

Synthesis Rxns

• Occur when two or more atoms or molecules combine to form a larger, more complex molecule.

• Always involve bond formation

• Energy absorbing rxns

• Underlie all anabolic activities that occur in body cells. Really important for growth and repair of worn out and damaged cells.

Decomposition Rxns.

• Occur when a molecule is broken down into smaller molecules, atoms, or ions.

• Synthesis rxns in reverse

• As bonds are broken energy is released

• Underlie all catabolic processes that occur in the body.

Exchange Rxns