BIO137 Chapter 2

Importance of Chemistry in Anatomy and Physiology

  • Chemistry studies the composition and changes of substances.

  • Human body, food, and medications consist of chemicals.

  • All anatomical structures and physiological processes relate to chemical reactions.

  • Water and electrolytes are essential components of body fluids.

Fundamentals of Chemistry

  • Matter: Anything that occupies space and has mass (solids, liquids, gases).

  • Mass: The amount of matter present.

  • Weight: Heaviness due to gravity's pull on mass.

  • Chemistry: The study of matter's composition and interactions.

  • Biochemistry: The study of chemical processes in living organisms.

Elements and Atoms

  • Elements: Simplest units with specific chemical properties (92 naturally occurring elements).

  • Atoms: Smallest particles that retain element properties.

  • Bulk Elements: Needed in large amounts (C, O, H, N, S, P).

  • Trace Elements: Needed in small amounts (Fe, I).

  • Ultratrace Elements: Required in minute quantities (As).

Atomic Structure

  • Atoms are composed of:

    • Protons: Positive charge, large particles.

    • Neutrons: No charge, large particles.

    • Electrons: Negative charge, small particles.

  • Atoms consist of a nucleus and electron shells.

  • Atoms are typically electrically neutral (equal protons and electrons).

Atomic Number & Mass Number

  • Atomic Number: Number of protons in an atom.

  • Mass Number: Total of protons and neutrons in the atom.

Isotopes

  • Isotopes have the same atomic number but different mass numbers (varying neutrons).

  • Some isotopes are radioactive and used in medical applications.

Molecules and Compounds

  • Molecule: Formed from atoms chemically combining.

  • Compound: Formed from different elements combining.

  • Molecular formulas denote the types and numbers of atoms.

Bonding of Atoms

  • Chemical bonds form from electron interactions.

  • Electron Shells: Regions encircling the nucleus where electrons reside.

  • Electron configurations determine bonding behavior.

Types of Chemical Bonds

  • Ionic Bonds: Formed from the attraction between charged ions (cations and anions).

  • Covalent Bonds: Formed by sharing electrons. Can be single or double bonds.

Structural Formulas

  • Show atom arrangements and types of bonds.

  • Indicate electron sharing through lines representing bonds.

Nonpolar & Polar Covalent Bonds

  • Nonpolar Covalent Bonds: Electrons shared equally.

  • Polar Covalent Bonds: Electrons shared unequally, resulting in partial charges (e.g., water).

Hydrogen Bonds

  • Weak attractions that occur between polar molecules, crucial for various biochemical structures.

Chemical Reactions

  • Involve the breaking/forming of chemical bonds.

  • Reactants: Starting materials; Products: End materials.

Types of Chemical Reactions

  • Synthesis: Form complex structures.

  • Decomposition: Break complex structures.

  • Exchange: Rearrange bonds.

  • Reversible: Change back to reactants.

Electrolytes, Acids & Bases, and Salts

  • Electrolytes: Substances releasing ions in water; can conduct electricity.

  • Acids: Release hydrogen ions.

  • Bases: Release ions that can combine with hydrogen ions.

  • Salts: Formed from acid-base reactions.

pH and Ion Concentration

  • pH measures acidity or alkalinity; scale from 0 (acid) to 14 (base).

  • Normal blood pH: 7.35-7.45.

Organic vs. Inorganic Substances

  • Organic Molecules: Contain C and H (e.g., carbohydrates, proteins).

  • Inorganic Molecules: Usually do not contain C and often dissociate in water (e.g., water, salts).

Organic Substances: Carbohydrates

  • Main energy source; includes sugars and starches.

  • Types:

    • Monosaccharides: Single sugars (e.g., glucose).

    • Disaccharides: Double sugars (e.g., sucrose).

    • Polysaccharides: Complex (e.g., starch).

Organic Substances: Lipids

  • Insoluble in water; includes fats, phospholipids, steroids.

  • Serve various functions, especially in membrane structure.

Organic Substances: Proteins

  • Functions: Structure, energy, enzymes, etc.

  • Made of amino acids linked by peptide bonds.

Protein Structure Levels

  • Primary: Amino acid sequence.

  • Secondary: Folding due to hydrogen bonding.

  • Tertiary: Final 3D shape; function dependent on shape.

  • Quaternary: Multiple polypeptide chains interacting.

Organic Substances: Nucleic Acids

  • Store genetic information (DNA) or assist in protein synthesis (RNA).

  • Composed of nucleotides.