Lecture 2: Body Chemistry - Chemistry of Life

Overview

• Focus on chemistry as it relates to the human body
• Review of previous lecture: Matter, energy, atoms, molecules, reactions, inorganic vs. organic
• Current focus: Water, ions, electrolytes, salts, acids, bases, pH, buffers, and organic molecules

Properties of Water

• Water's role as a polar molecule
  • Oxygen has partial negative, hydrogen has partial positive
  • Dipole moment: Polarity leads to properties like surface tension, dissolving ability
• Water as a solvent
  • Dissolves ionic compounds (e.g., NaCl)
  • Hydration shells formed around ions
• Aqueous solutions
  • Electrolytes: Solutions with ions that carry electric charges (e.g., Na+, K+, Ca2+)
  • Importance for body fluid balance

Inorganic Chemistry

• Acids and Bases
  • pH scale: Measure of hydrogen ion concentration
  • Acidic (pH < 7), Basic (pH > 7), Neutral (pH = 7)
  • Physiological pH: Blood between 7.35 - 7.45
• Buffers
  • Resist changes in pH by absorbing or donating H+ ions
  • Important in maintaining body's pH balance

Organic Chemistry

• Organic molecules contain hydrocarbons
• Four classes: Carbohydrates, Lipids, Proteins, Nucleic Acids

Carbohydrates

• Composed of carbon, hydrogen, and oxygen
• Types: Monosaccharides, Disaccharides, Polysaccharides
  • Monosaccharides: Simple sugars (e.g., glucose, fructose)
  • Disaccharides: Two monosaccharides joined (e.g., sucrose)
  • Polysaccharides: Storage form (glycogen in animals, starch in plants)

Lipids

• Hydrophobic molecules (e.g., fats, oils, waxes)
• Categories: Fatty acids, Eicosanoids, Glycerides, Steroids, Phospholipids, Glycolipids
• Structure and function
  • Saturated vs. unsaturated fatty acids
  • Triglycerides as energy storage
  • Phospholipids in cell membranes (hydrophilic head, hydrophobic tail)
  • Steroids derived from cholesterol (e.g., hormones like testosterone and estrogen)

Key Concepts

• Hydrophobic vs. Hydrophilic
  • Hydrophobic: Lipid-loving, water-fearing
  • Hydrophilic: Water-loving, lipid-fearing
• Redox Reactions
  • Exchange of electrons in cellular respiration

Look Forward

• Next discussion on proteins
• Importance in metabolism and cellular functions

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This lecture provided an extensive overview of inorganic and organic chemistry relevant to biological systems, giving a foundational understanding necessary for further studies in physiology and biochemistry.