Principles of Anatomy and Physiology

Principles of Anatomy and Physiology
14th Edition CHAPTER 2 The Chemical Level of Organization Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
Introduction The purpose of the chapter is to: Introduce the language and fundamental concepts of chemistry Discuss how matter is organized Discuss how chemical bonds form and how chemical reactions occur Compare and contrast organic and inorganic compounds Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

Basic Principles of Chemistry
Chemistry is the science of structure and interactions of matter Matter is anything that has mass and takes up space Mass is the amount of matter a substance contains, whereas weight is the force of gravity acting on a mass Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

Atoms Chemical elements are composed of units of matter of the same type called atoms Atoms are the smallest units of matter that retain the properties and characteristics of an element Atoms are composed of: Protons Neutrons Electrons Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

Atomic Number and Mass Number
Atomic number is the number of protons in the nucleus of an atom, since the number of protons and electrons is the same the atom is said to be neutral. Mass number is the number of protons and neutrons in an atom Isotopes Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

Atomic Mass Atomic mass assumes the mass of a: Neutron = daltons Proton = daltons Electron = daltons The atomic mass/weight of an element is the average mass of all its naturally occurring isotopes Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

Elements Elements are given chemical symbols such as: O = oxygen C = carbon H = hydrogen N = nitrogen These elements make up the majority of our bodies Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

Trace Elements of the Human Body
Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

Molecules, Mixtures and Compounds
Molecule – 2 or more atoms held together by chemical bonds Compound – a substance that can be chemically broken down into 2 or more different elements Mixture – a substance that can be physically broken down into 2 or more elements or compounds Solution – homogeneous mixture (mineral water) Colloid – heterogeneous mixture (jello) Suspension – heterogeneous mixture with large often visible solutes (blood) Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

Chemical Bonds A chemical bond occurs when atoms are held together by forces of attraction The number of electrons in the valence shell determines the likelihood that an atom will form a chemical bond with another atom Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

Ions Ion – an atom that has lost or gained an electron anion – atom that gains one or more electrons; has a negative charge cation – atom that loses one or more electrons; has a positive charge Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

Polar and Nonpolar Covalent Bonds
Polar Covalent Bond – Unequal sharing of electrons; one end has a slightly negative charge and one end has a slightly positive charge Example - Water Nonpolar Covalent Bond – Equal sharing of electrons; charge is balanced among atoms Example – Carbon Dioxide Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

Chemical Reactions A chemical reaction occurs when new bonds are formed or old bonds are broken Reactants – starting substances Products – ending substances Metabolism Law of conservation of mass Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

Inorganic vs. Organic Compounds
Inorganic compounds usually lack carbon and are simple molecules Water is the most important and abundant inorganic compound in all living things Organic compounds always contain H, usually contain O, and always have covalent bonds Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

Properties of Water Interactions Animation: Polarity and Solubility of Molecules You must be connected to the Internet and in Slideshow Mode to run this animation. Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

Water as a Polar Molecule
Water’s polar quality allows it to dissolve many different substances making it the universal solvent. Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

Water in Chemical Reactions
Water is the ideal medium In a hydrolysis reaction, water is added to break bonds In a dehydration synthesis reaction, water is removed to make bonds Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

Water as a Lubricant Water is a major component of our body fluids and helps reduce friction as membranes and organs slide over one another Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

Water’s Thermal Properties
Water has a: High heat capacity – it absorbs and releases large amounts of heat before changing appreciably in temperature itself…prevents sudden changes in temperature caused by external factors High heat of vaporization – water requires a large amount of energy to evaporate (break the hydrogen bonds that hold water together) Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

Water’s Other Properties
Capillary Action – ability of water to creep up thin tubes; Caused by: Cohesion – ability of water to bond with other water molecules Adhesion – ability of water to adhere to other substances Surface Tension - Hydrogen bonding causes water molecules to stick together causing high surface tension. Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

pH The strength of an acid or base in a solution is measured on a scale called the pH scale. The pH scale is based on the number of hydrogen ions in solution. It spans from 0 to 14. The middle point (pH 7) is neutral (neither basic nor acidic). Any pH greater than 7 is considered a base or alkaline and any pH number less than 7 is considered an acid. 0 is the strongest acid and 14 is the strongest base. Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

Acids Acids are ionic compounds (having a positive or negative charge) that breaks apart in water to form hydrogen (H+) ions. Acids are sour, react with metals, and strong acids can burn skin. Acids turn blue litmus paper red. Battery Acid = pH 0 Stomach Acid = pH 1 Lemon Juice or Vinegar = pH 2 Soft Drinks or Pickles = pH 3 Acid Rain or Tomato Juice = pH 4 Black Coffee or Butter = pH 5 Saliva or Urine = pH 6 Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

Bases Bases are ionic compounds (having a positive or negative charge) that breaks apart in water to form hydroxide (OH-) ions. Bases are bitter, feel slippery, and strong bases can burn skin. Bases turn red litmus paper blue. Sea Water or Canteloupe = pH 8 Baking Soda or Pears = pH 9 Milk of Magnesia or Antacids= pH 10 Ammonia = pH 11 Soapy Water = pH 12 Bleach = pH 13 Drain Cleaner = pH 14 Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

Buffer Systems Maintenance of body fluid homeostasis is critical Buffer systems help to regulate pH by converting strong acids or bases into weak acids or bases Buffers resist abrupt and large swings in the pH of body fluids by releasing H+ ions when pH begins to rise and by binding H+ ions when pH drops. Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

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