ESSENTIALS OF HUMAN ANATOMY & PHYSIOLOGY Chapter 2 Lecture Notes

Matter and Energy Matter – anything that occupies space and has mass (weight); the “stuff” of the universe 3 states of matter: Solid Liquid Gas

Matter and Energy Energy – the ability to do work; putting matter into motion; massless 4 forms of energy: Chemical Electrical Mechanical Radiant

Composition of Matter Elements – fundamental units of matter Periodic table – lists all 112 elements, their 1 or 2 letter symbols, atomic number, and atomic weights 4 elements compose approximately 96% of the human body: Carbon (C) Oxygen (O) Hydrogen (H) Nitrogen (N)

Atomic Structure Atoms – building blocks of elements Nucleus – center of every atom an contains: Protons (p+) = positive charge Neutrons (n0) = no charge Outside of the nucleus contains: Electrons (e-) = negative charge

Atomic Structure

Identifying Elements Atomic Number – equal to the number of protons that the atom contains Atomic Mass – the sum of the protons and the neutrons

Molecules and Compounds Molecule – 2 or more LIKE atoms combined chemically Example: H (atom) + H (atom) = H2 Compound – 2 or more DIFFERENT atoms combined chemically Example: 4H + C = CH4 (methane)

Chemical Bonds and Reactions Chemical Reactions – occur whenever atoms combine with, or dissociate from, other atoms Atoms are united by chemical bonds Electrons occupy energy levels called electron shells Electrons closest to the nucleus are most strongly attracted

Chemical Bonds and Reactions Each electron shell has distinct properties: Number of electrons has an upper limit Shells closest to nucleus fill first Shell 1 can hold 2 electrons Shell 2 can hold 8 electrons Shell 3 can hold 18 electrons

Chemical Bonds and Reactions Valence Shell – outermost shell that contains electrons Bonding involves interactions between electrons in the valence shell Full valence shells do not form bonds Inert Elements – have complete valence shells and are stable Rule of 8’s – atoms interact so that they will have 8 electrons in their valence shell

Types of Chemical Bonds Ionic Bonds – form when electrons are completely transferred from one atom to another Na + Cl = NaCl Ions – are charged particles; they either donate or accept electrons Anions = negative ions Cations = positive ions

Types of Chemical Bonds Covalent Bonds – shared electron bonding Single covalent bonds share one electron H + H = H2 Double covalent bonds share two electrons O + O = O2 Hydrogen Bonds – weak covalent bond where H is attracted to negative portion of a polar molecule

Examples of Covalent Bonds

Types of Chemical Reactions Synthesis Reaction – atoms or molecules combine and energy is absorbed for bond formation A + B = AB Decomposition – molecule is broken down and energy is released AB = A + B

Examples of Chemical Reactions

Types of Chemical Reactions Exchange Reactions – involves both synthesis and decomposition reactions. A switch is made between molecule parts and different molecules are made. AB + CD = AD + CB

Biochemistry: Essentials for Life Two major classes of molecules: Organic Compounds = contain carbon and most are covalently bonded Inorganic Compounds = lack carbon and tend to be simpler compounds

Organic Compounds Carbohydrates – contain C, H, and O and include sugars and starches; are classified according to their size: Monosaccharide – simple sugars Glucose Disaccharides – 2 simple sugars joined by dehydration synthesis or hydrolysis Sucrose = glucose + fructose Polysaccharides – long branching chains of linked simple sugars starch

Examples of Sugars

Examples of Sugars

Organic Compounds Lipids – contain C, H, and O; C and H outnumber O; are insoluble in water Triglycerides (neutral fats) – found in fat deposits and are composed of fatty acids and glycerol; source of stored energy Phospholipids – form cell membrane Steroids – include cholesterol, vitamin D, and some hormones

Organic Compounds Proteins – contain C, O, H, N and sometimes S; made up of amino acids Account for over half of the body’s organic matter Provides for construction materials for body tissues Plays a vital role in cell function Act as enzymes, hormones, and antibodies Enzymes = act as biological catalysts which increase the rate of chemical reactions

Organic Compounds Nucleic Acids – provide the blueprint for life; make DNA and RNA and are composed of nucleotide bases: Adenine Guanine Cytosine Thymine – found only in DNA Uracil – found only in RNA DNA = DeOxyRiboNucleic Acid – provides instruction for every protein in the body RNA = RiboNucleic Acid

DNA

Organic Compounds Adenosine TriPhosphate (ATP) – chemical energy used by all cells; energy is released by breaking high energy phosphate bonds and producing ADP

Inorganic Compounds H2O (water) – most abundant inorganic compound Salts – easily dissociate into ions in the presence of water and they are vital to many body functions; include the electrolytes which conduct electrical currents

Inorganic Compounds Acids – are proton donators; can release detectable H ions; have a sour taste and can dissolve many metals or “burn” holes in materials Bases – are proton acceptors; have a bitter taste and feel slippery Neutralization Reaction = acids and bases react to form water and a salt

pH Measurements pH = measures relative concentrations of H ions pH 7 = neutral pH < 7 = acidic pH > 7 = basic Buffers = chemicals that can help regulate pH change