Elsevier items and derived items © 2007, 2003, 2000 by Saunders, an imprint of Elsevier Inc.Slide 1 Chapter 2 Basic Chemistry B. Souto

Elsevier items and derived items © 2007, 2003, 2000 by Saunders, an imprint of Elsevier Inc.Slide 2 Introduction  Our bodies are made of different chemicals. To understand the body, you need to understand some general chemical principles.

Elsevier items and derived items © 2007, 2003, 2000 by Saunders, an imprint of Elsevier Inc. Matter, Elements, and Atoms Matter  Matter is anything that occupies space and has weight.  Matter exists in three states: solid, liquid, and gas.  Matter can undergo physical and chemical changes. Slide 3

Elsevier items and derived items © 2007, 2003, 2000 by Saunders, an imprint of Elsevier Inc. Matter, Elements, and Atoms - cont’d  Element a fundamental substance that cannot be broken down into a simpler form by ordinary chemical means.  Abundant (Table 2- 1)  Four elements ( 96% body wt)  ( C, H, O 2 and N) make up 96% of the body weight.  Trace  Symbols Slide 4

Elsevier items and derived items © 2007, 2003, 2000 by Saunders, an imprint of Elsevier Inc. Matter, Elements, and Atoms - cont’d  Atoms  An atom is the basic unit of matter.  An atom is composed of three subatomic particles: neutrons, protons, and electrons.  The atomic number: the number of protons.  The atomic weight: the number of neutrons and protons.  An isotope is an atom with the same atomic number but a different atomic weight. A radioisotope is an unstable isotope. Slide 5

Elsevier items and derived items © 2007, 2003, 2000 by Saunders, an imprint of Elsevier Inc. Chemical Bonds  Electron Shells and Bonding  Each electron shell holds a specific number of electrons.  Ionic bonds are formed as electrons are transferred to stabilize the shells of the atoms.  Covalent bonds are formed as the electrons of the outer shells are shared by the interacting atoms.  Hydrogen bonds are intermolecular bonds. Slide 6

Elsevier items and derived items © 2007, 2003, 2000 by Saunders, an imprint of Elsevier Inc.Slide 7 Chemical Bonds - cont’d  Ion Formation  An ion is an atom that carries an electrical charge. A cation is a positively charged ion. An anion is a negatively charged ion.  An electrolyte is a substance that forms ions when dissolved in water.

Elsevier items and derived items © 2007, 2003, 2000 by Saunders, an imprint of Elsevier Inc. Slide 8 Chemical Bonds - cont’d  Molecules and Compounds  A molecule is a substance formed by two or more atoms (O 2, H 2 O).  A compound is a substance that forms when two or more different atoms bond (H 2 O).  Important molecules and compounds include water, oxygen, and carbon dioxide.

Elsevier items and derived items © 2007, 2003, 2000 by Saunders, an imprint of Elsevier Inc. Important Compounds and Molecules  Water  Acts as a universal solvent  Good temperature regulator  Acts as an excellent lubricant  Plays a crucial role in chemical reactions  Acts as a cushion, thereby performing a protective role  Oxygen ( O 2 )  The air we breathe contains 21% oxygen  Necessary for human life ( 4-6 minutes)  Used by the cells to liberate energy  Carbon dioxide : waste formed by metabolizing (working) cells Slide 9

Elsevier items and derived items © 2007, 2003, 2000 by Saunders, an imprint of Elsevier Inc. Chemical Reactions, Enzymes and Catalysts Slide 10

Elsevier items and derived items © 2007, 2003, 2000 by Saunders, an imprint of Elsevier Inc. Chemical Bonds - cont’d Acids and Bases  An acid is an electrolyte that dissociates into a hydrogen ion (H + ) and an anion.  A base is a substance that combines with H + and eliminates H + ; a base neutralizes an acid by producing a salt and water.  The pH scale measures acidity and alkalinity. A pH of 7 is neutral. A pH less than 7 is acidic, and a pH greater than 7 is basic, or alkaline. Slide 11 Is the pH of blood acidic or alkaline?

Elsevier items and derived items © 2007, 2003, 2000 by Saunders, an imprint of Elsevier Inc. Chemical Bonds - cont’d Acids and Bases—cont’d  The normal pH of the blood is 7.35 to A person with a pH less than 7.35 is acidotic, and a person with a pH greater than 7.45 is alkalotic.  Blood pH is regulated by buffers, the respiratory system, and the kidneys. Slide 12 HH H↓

Elsevier items and derived items © 2007, 2003, 2000 by Saunders, an imprint of Elsevier Inc. Energy Energy- the ability to do work. Forms of Energy  Mechanical energy, as in muscle contraction and movement  Chemical energy, as in the digestion of food  Identify the 6 forms of energy: see Table 2-3.  Most energy is released as heat.  Role of Adenosine Triphosphate (ATP)  ATP is an energy-transfer molecule.  The energy is stored in high-energy phosphate bonds. Slide 13

Elsevier items and derived items © 2007, 2003, 2000 by Saunders, an imprint of Elsevier Inc. ATP (Adenosine TriPhosphate)  Is a short term energy storage molecule. All cell processes are powered by ATP. Our food energy must always be converted to ATP energy for use by the cell!  The diagram shows ADP (adenosine diphosphate) gaining energy as glucose "burns" so that an extra P (phosphate) can be added to make energy rich ATP. The ATP is then ready to give its energy to the cell when needed! Slide 14

Elsevier items and derived items © 2007, 2003, 2000 by Saunders, an imprint of Elsevier Inc. Mixtures, Solutions, and Suspensions  A mixture is a blend of two or more substances that can be separated by ordinary physical means.  Solutions  Solute  Solvent  Aqueous solution  Suspensions  colloidal  colloid Slide 15

Elsevier items and derived items © 2007, 2003, 2000 by Saunders, an imprint of Elsevier Inc. What’s the Clinical Significance?  Concern for the patient with high/low plasma K +  Concern for the patient’s “lytes”  Enzyme deficiency diseases (e.g., PKU, lactose intolerance)  Use of antacids in the treatment of gastric acidity  An uncontrolled diabetic is making excess ketoacids and has a blood pH of 7.2  Some drugs are prepared as suspensions and must be shaken in order to ensure correct drug dose  Some IV drug solutions form dangerous precipitates upon standing (e.g., mannitol)  Many insulin preparations are suspensions and therefore cannot be administered intravenously Slide 16