Basic Chemistry

Introduction

Chemistry forms the foundation for understanding the structure and function of the human body. This chapter introduces the essential chemical principles necessary for the study of anatomy and physiology, focusing on matter, energy, atomic structure, chemical bonds, and the major classes of biological molecules.

2-1 Matter and Energy

Definitions and Differences

• Matter: Anything that occupies space and has mass. All substances in the body are forms of matter.

• Energy: The capacity to do work or cause change. Energy does not have mass or occupy space.

• Kinetic energy: energy is doing work

• Potential energy: energy is inactive or stored

Major Forms of Energy in the Body

• Chemical Energy: Stored in the bonds of chemical substances. Example: ATP provides energy for cellular processes.

• Electrical Energy: Results from movement of charged particles. Example: Nerve impulses are electrical signals.

• Mechanical Energy: Directly involved in moving matter. Example: Muscle contraction moves body parts.

2-2 Elements and Atoms

Elements and Their Importance

• Element: A pure substance composed of only one type of atom. Cannot be broken down by ordinary chemical means.

• Major Elements in the Body: Oxygen (O), Carbon (C), Hydrogen (H), and Nitrogen (N) form about 96% of body mass.

• The number each element has is the number of protons.

Atoms and Subatomic Particles

• Atom: The smallest unit of an element that retains its properties.

• Subatomic Particles:

  • Protons: Positive charge, located in the nucleus.

  • Neutrons: No charge, located in the nucleus.

  • Electrons: Negative charge, orbit the nucleus in electron shells.

2-3 Chemical Bonds and Reactions

Chemical Bonds

• Chemical Reactions: Involve the making and breaking of bonds between atoms through electron interactions.

• Ionic Bonds: Formed when electrons are transferred from one atom to another, creating charged ions (e.g., NaCl).

• Covalent Bonds: Formed when atoms share electrons.

  • Polar Covalent Bonds: Unequal sharing of electrons (e.g., water).

  • Nonpolar Covalent Bonds: Equal sharing of electrons (e.g., O2).

• Hydrogen Bonds: Weak attractions between polar molecules, important in water and DNA structure.

Types of Chemical Reactions

• Synthesis Reactions: Atoms or molecules combine to form larger, more complex molecules. Example:

• Decomposition Reactions: Molecules are broken down into smaller parts. Example:

2-4 Molecules and Compounds

Definitions

• Molecule: Two or more atoms held together by chemical bonds (e.g., O2).

• Compound: A molecule containing two or more different elements (e.g., H2O).

2-5 Inorganic and Organic Compounds

Classification and Importance

• Inorganic Compounds: Usually lack carbon; include water, salts, acids, and bases.

• Organic Compounds: Contain carbon; include carbohydrates, lipids, proteins, and nucleic acids.

Water and Homeostasis

• Water: Most abundant inorganic compound in the body; vital for temperature regulation, chemical reactions, and transport.

Salts, Acids, and Bases

• Salt: Ionic compound that dissociates in water to form ions.

• Acid: Releases hydrogen ions (H+) in solution.

• Base: Accepts hydrogen ions or releases hydroxide ions (OH-).

pH Concept

• pH: Measures hydrogen ion concentration; scale ranges from 0 (acidic) to 14 (basic).

• Blood pH: Maintained around 7.4 (slightly basic).

Dehydration Synthesis and Hydrolysis

• Dehydration Synthesis: Joins molecules by removing water.

• Hydrolysis: Breaks molecules by adding water.

Carbohydrates vs. Lipids

• Carbohydrates: Building blocks are monosaccharides; provide quick energy; structure includes rings of carbon, hydrogen, and oxygen.

• Lipids: Building blocks are fatty acids and glycerol; store energy, form cell membranes; structure includes long hydrocarbon chains.

2-5 Nucleic Acids and ATP

DNA and RNA

• DNA (Deoxyribonucleic Acid): Double-stranded; stores genetic information.

• RNA (Ribonucleic Acid): Single-stranded; involved in protein synthesis.

ATP (Adenosine Triphosphate)

• ATP: The primary energy carrier in cells; energy is released when its phosphate bonds are broken.

Additional info: This summary expands on the learning objectives by providing definitions, examples, and comparisons to ensure a comprehensive understanding of basic chemistry as it applies to human anatomy and physiology.