Anatomy and Physiology - Chapter 2: The Chemical Level of Organization

Introduction to Chemistry in Physiology

• Definition of Chemistry: Science dealing with the structure of matter.
• Matter: Anything that takes up space and has mass, made up of atoms.
• Atoms: Smallest stable units of matter, made of subatomic particles:
  • Protons: Positive charge
  • Neutrons: Neutral charge
  • Electrons: Negative charge

Atomic Structure

• Nucleus: Center of the atom containing protons and neutrons.
• Electron Cloud: Area containing electrons, usually depicted as an electron shell in 2D models.
• Atomic Number: Number of protons in an atom.
• Element: Pure substance of the same kind of atoms.
• Isotopes: Atoms with the same number of protons but different neutrons.

Electrons and Reactivity

• Electron Cloud: Determines atom's reactivity.
• Valence Shell: Outermost shell, determines bonding.
  • Atoms with unfilled valence shells are more reactive.
  • Atoms with filled valence shells are stable.

Types of Chemical Bonds

• Ionic Bonds:
  • Between atoms of opposite charges.
  • Involves electron donor (cation) and electron acceptor (anion).
• Covalent Bonds:
  • Strong bonds involving shared electrons.
  • Can be nonpolar (equal sharing) or polar (unequal sharing).
• Hydrogen Bonds:
  • Weak polar bonds based on electrical attractions.

Chemical Reactions

• Reactants and Products: Reactants are inputs; products are outputs.
• Metabolism: All reactions occurring in the body.
• Energy:
  • Kinetic Energy: Energy of motion.
  • Potential Energy: Stored energy.

Types of Reactions

• Decomposition (Catabolism): Breaking chemical bonds.
• Synthesis (Anabolism): Forming chemical bonds.
• Enzymes: Protein catalysts lowering activation energy.

Water and Solutions

• Water is critical in the body, making up 2/3 of body weight.
• pH Scale: Measures hydrogen ion concentration.
  • Acidic: pH 0-6
  • Neutral: pH 7
  • Basic: pH 8-14
• Buffers: Resist changes in pH.

Organic Molecules

• Carbohydrates: Sugars and starches.

  • Monosaccharides: Simple sugars (e.g., glucose).
  • Disaccharides: Two monosaccharides (e.g., sucrose).
  • Polysaccharides: Many sugars (e.g., starch).

• Lipids: Fats, oils, and waxes.

  • Includes fatty acids, phospholipids (important in cell membranes).

• Proteins: Made of amino acids, joined by peptide bonds.

  • Have four structures (primary, secondary, tertiary, quaternary).
  • Denaturation: Loss of protein shape due to external factors.

• Nucleic Acids: DNA and RNA.

  • DNA: Double helix, stores genetic information.
  • RNA: Single-stranded, involved in protein synthesis.

High-Energy Compounds

• ATP (Adenosine Triphosphate): Energy currency of cells.
• ADP (Adenosine Diphosphate) and AMP (Adenosine Monophosphate): Related energy compounds.

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• Conclusion: Understanding chemistry is essential for exploring physiology, as chemical characteristics influence processes at molecular and cellular levels.
• Next Chapter: Focus on the cell.