Recording-2025-03-14T15_51_00.105Z

Introduction to Chemistry and Physiology

• Chemistry is fundamental to physiology, underpinning all biological processes.

• Focus will be on essential concepts to understand physiological processes like electrochemical gradients and ion channels.

• No expectation to perform complex chemical calculations such as balancing reactions or calculating concentrations.

Elements and Matter

• Everything is made of matter, which cannot be broken down by ordinary chemical means.

• Periodic Table: Comprises various elements; not all are relevant to physiology.

Major Elements in the Human Body

• Six Elements make up 98.7% of human mass:

  • Oxygen (O)

  • Carbon (C)

  • Hydrogen (H)

  • Nitrogen (N)

  • Calcium (Ca)

  • Phosphorus (P)

• Additional Lesser Elements:

  • Sulfur (S)

  • Potassium (K)

  • Sodium (Na)

  • Chlorine (Cl)

  • Magnesium (Mg)

  • Iron (Fe)

• Trace Elements: Required in minuscule amounts, e.g., Iodine (for thyroid function), Zinc (in liver enzymes).

Atoms and Isotopes

• Atoms: The smallest unit of an element containing protons, neutrons, and electrons.

• Subatomic Structure:

  • Protons: Positively charged particles in nucleus.

  • Neutrons: Uncharged particles in nucleus.

  • Electrons: Negatively charged particles orbiting nucleus.

• Isotopes: Variants of elements with the same number of protons but different neutrons (e.g., Hydrogen has isotopes Hydrogen, Deuterium, Tritium).

Molecules and Compounds

• Molecule: Composed of two or more atoms bonded together.

• Compound: Composed of different elements chemically bonded together.

• Chemical bonds enable molecules to form through interactions between electrons.

Types of Chemical Bonds

1. Ionic Bonds: Formed through the transfer of electrons, creating charged ions that attract each other (e.g., NaCl).

2. Covalent Bonds: Atoms share electrons, can be single, double, or triple bonds. Stronger than ionic bonds.

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

   • Nonpolar Covalent Bonds: Equal sharing of electrons.

3. Hydrogen Bonds: Weak attractions between polar molecules (e.g., water molecules).

Mixtures and Solutions

• Homogeneous Mixtures: Uniform mixtures (e.g., saltwater).

• Solutions: Comprise solvent (liquid) and solute (dissolved substance); concentration expressed in molarity or mg/dL.

• Colloids: Mixtures with particles that do not settle out (e.g., Jell-O with fruit).

• Suspensions: Mixtures where solutes settle out over time (e.g., blood).

Chemical Reactions

• Types of Reactions:

  1. Synthesis (Anabolic) Reactions: Build larger molecules from smaller ones, require energy.

  2. Decomposition (Catabolic) Reactions: Break down larger molecules into smaller ones, release energy.

  3. Exchange Reactions: Combine synthesis and decomposition.

• Reversibility: Most biological reactions are not reversible due to product removal.

• Factors Affecting Reaction Rates: Include temperature, particle size, concentration, and catalysts (e.g., enzymes).

pH and Acid-Base Balance

• Acids and Bases:

  • Acid: Proton donor (H+).

  • Base: Proton acceptor.

• pH Scale: Ranges from 0 (acidic) to 14 (basic); blood pH is tightly regulated between 7.35 and 7.45.

• Buffers: Substances that resist changes in pH, converting strong acids/bases into weaker forms.

Organic Compounds

• Types: Carbohydrates, lipids, proteins, nucleic acids.

• Carbohydrates: Formed from monosaccharides, disaccharides, polysaccharides, serve primarily as energy sources.

• Lipids: Comprised of fatty acids, include saturated (solid at room temp) and unsaturated fats (liquid at room temp), function in energy storage and cell membranes.

• Proteins: Composed of amino acids; structure determines function; various levels of structure (primary, secondary, tertiary, quaternary).

• Nucleic Acids: DNA (genetic material) and RNA, composed of nucleotides; involved in protein synthesis.

Enzymes and Energy Transfer

• Enzymes: Biological catalysts that speed up reactions by lowering activation energy.

• ATP: Primary energy carrier in cells, releases energy for cellular functions.

Summary

• Understanding the role of chemicals in physiology is crucial for grasping complex biological processes.

• Discussions will progress to cellular biology in subsequent lessons.