Chapter 2: Chemistry, Matter, and Life

Chapter 2: Chemistry, Matter, and Life

Chapter 2 Chemistry, Matter, and Life Copyright 2016 Wolters Kluwer All Rights Reserved Chemistry Science that deals with matters composition and properties Used to understand normal and abnormal body function Copyright 2016 Wolters Kluwer All Rights Reserved Elements and Matter 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 Copyright 2016 Wolters Kluwer All Rights Reserved Periodic Table of the Elements Appendix 1 What is the symbol and number for carbon? Copyright 2016 Wolters Kluwer All Rights Reserved Some Common Elements Table 2-1 Name **Oxygen Symbol

O Function Part of water; needed to metabolize nutrients for energy Carbon C Basis of all organic compounds; component of carbon dioxide, the gaseous byproduct of metabolism Hydrogen H Part of water, participates in energy metabolism; determines the acidity of body fluids Nitrogen N

Present in all proteins, ATP (the energy-storing compound), and nucleic acids (DNA and RNA) **Calcium Ca Builds bones and teeth; needed for muscle contraction, nerve impulse conduction, and blood clotting Phosphorus P Active ingredient in ATP; builds bones and teeth; component of cell membranes and nucleic acids Potassium K

Active in nerve impulse conduction; muscle contraction Sulfur Sodium S Na Iron Fe 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 The elements are listed in decreasing order by weight in the body. Copyright 2016 Wolters Kluwer All Rights Reserved The Bodys Chemical Composition by Weight

Fig. 2-1 Copyright 2016 Wolters Kluwer All Rights Reserved Atoms Smallest subunits of elements Cannot be broken down or changed by ordinary chemical and physical means Copyright 2016 Wolters Kluwer All Rights Reserved Atomic Structure Nucleus At atoms center Composed of Protons; positively charged

Neutrons; not charged Electrons Negatively charged Orbit in energy levels around the nucleus Determine atoms chemical reactivity Copyright 2016 Wolters Kluwer All Rights Reserved Atomic Number Equal to the number of protons in an atoms nucleus. Also represents the number of electrons orbiting the nucleus.

No two elements share the same atomic number. 8 Oxygen O 16.00 Oxygens nucleus contains 8 protons. Its atomic number is 8. Copyright 2016 Wolters Kluwer All Rights Reserved Energy Levels Regions around an atoms 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. Copyright 2016 Wolters Kluwer All Rights Reserved Energy Levels of Common Atoms 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. Copyright 2016 Wolters Kluwer All Rights Reserved 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. Copyright 2016 Wolters Kluwer All Rights Reserved 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. Carbons valence is 4. Copyright 2016 Wolters Kluwer All Rights Reserved 6 Carbon C 12.01 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. Na+ Copyright 2016 Wolters Kluwer All Rights Reserved Cl 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 are electrolytes.

Copyright 2016 Wolters Kluwer All Rights Reserved Electrolytes (cont.) Electrolytes (ions) conduct electric currents in body fluid. Measurement of a tissues electrical activity is used to diagnose disease. Examples Electrocardiogram A record of the hearts electrical activity Electroencephalogram A record of the brains electrical activity Copyright 2016 Wolters Kluwer All Rights Reserved Important Ions in the Body Ions and Their Functions Ion

Functions Ca2+ Blood clotting, muscle contraction HCO3 pH regulation Homeostasis maintains ion concentrations within tight limits. Copyright 2016 Wolters Kluwer All Rights Reserved 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. Copyright 2016 Wolters Kluwer All Rights Reserved Molecules and Compounds 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 Copyright 2016 Wolters Kluwer All Rights Reserved Types of 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 Copyright 2016 Wolters Kluwer All Rights Reserved 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 bodys chemical reactions Some substances are hydrophobic Copyright 2016 Wolters Kluwer All Rights Reserved 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 Salt NaOH Na+ + OH A substance formed by a reaction between an acid and a base HCl + NaOH NaCl + H2O Copyright 2016 Wolters Kluwer All Rights Reserved The pH Scale Indicates 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

Copyright 2016 Wolters Kluwer All Rights Reserved The pH Scale (cont.) Fig. 2-7 Copyright 2016 Wolters Kluwer All Rights Reserved Buffers Chemicals that prevent sharp changes in H+ concentration Are important in maintaining a relatively constant pH in body fluids Copyright 2016 Wolters Kluwer All Rights Reserved 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 May be stable or unstable (radioactive) Carbon-14 6 8 Copyright 2016 Wolters Kluwer All Rights Reserved 13 14 Radioactivity 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 abnormalitiesthese are called tracers. Example: Radioactive iodine is used to diagnose thyroid problems. Copyright 2016 Wolters Kluwer All Rights Reserved 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 Copyright 2016 Wolters Kluwer All Rights Reserved 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

Copyright 2016 Wolters Kluwer All Rights Reserved 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) Copyright 2016 Wolters Kluwer All Rights Reserved Proteins Contain nitrogen (and sometimes sulfur or phosphorus), carbon, hydrogen and oxygen 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.

Copyright 2016 Wolters Kluwer All Rights Reserved Enzymes 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) Copyright 2016 Wolters Kluwer All Rights Reserved 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 Copyright 2016 Wolters Kluwer All Rights Reserved 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 the 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 waterthey mix with or dissolve in it. -phobia fear Hydrophobic substances fear water they repel and do not dissolve in it.

Copyright 2016 Wolters Kluwer All Rights Reserved 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. Copyright 2016 Wolters Kluwer All Rights Reserved

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