Lecture Notes on Chemistry and Physiology

Introduction

• Review of basic high school chemistry is necessary but won't be covered in detail in class. Use resources in the book for self-review.
• Focus will be on elements in the body and their roles in physiology.

Elements in the Human Body

• Major Elements: Oxygen, Carbon, Hydrogen, Nitrogen.
  • Hydrogen and Oxygen form water.
  • Carbon and Nitrogen are in proteins that form connective tissue.
• Trace Elements: Sodium, Potassium, Calcium, Iron.
  • Critical for functions like muscle contraction and nerve conduction.
  • Calcium is highlighted for its importance in physiological functions.

Enzymes

• Enzymes are molecules that assist in chemical reactions by lowering activation energy.
• They convert reactants into products more efficiently, allowing reactions to occur faster and at lower energies.
• Example: Thrombin enzyme converts fibrinogen to fibrin in blood clotting.

Importance of Water

• Solubility: Water is an excellent solvent; dissolves many substances like sodium chloride.
• Reactivity: Participates in reactions such as hydrolysis and dehydration.
• Polarity and Solvent Properties: Water's polarity allows it to form hydration spheres around ions, enabling them to stay in solution.
• Heat Capacity: High heat capacity helps stabilize body temperature and aids in cooling through evaporation.
• Lubrication: Provides lubrication in joints and membranes.

pH and Acidity

• pH Scale: Measures acidity in solutions; 7 is neutral.
• Acids and Bases: Acids release hydrogen ions (H+), bases release hydroxide ions (OH-).
• Buffers: Maintain stable pH by neutralizing excess acids or bases.

Biological Molecules

Carbohydrates

• Composed of Carbon, Hydrogen, and Oxygen in a 1:2:1 ratio.
• Types:
  • Monosaccharides: Simple sugars like glucose, fructose, galactose.
  • Disaccharides: Two monosaccharides linked, e.g., sucrose.
  • Polysaccharides: Long chains of monosaccharides, e.g., glycogen (animal starch), starch (plants).
• Preferred source of fuel for the body, especially the brain.

Lipids

• Made of Carbon, Hydrogen (more than carbohydrates), and Oxygen.
• Types of Lipids:
  • Saturated Fats: No double bonds; primarily from animal sources.
  • Unsaturated Fats: One or more double bonds; primarily from plants.
  • Glycerides: Triglycerides are the most common, used for energy storage.
  • Eicosanoids and Steroids: Chemical messengers and hormones like estrogen, testosterone.
  • Phospholipids: Form cell membranes; have hydrophilic heads and hydrophobic tails.

Summary

• Water, carbohydrates, lipids, and proteins are essential components of the body.
• Understanding the chemical basis of these elements and compounds is crucial for studying physiology.