Basic Chemistry for Anatomy & Physiology: Mini-Textbook Study Notes

Basic Chemistry for Anatomy & Physiology

Introduction

Chemistry forms the foundation for understanding biological processes in Anatomy & Physiology. This section covers essential chemical concepts, including matter, energy, atomic structure, chemical bonds, reactions, and the major classes of biological molecules.

Matter and Energy

Definitions and Key Concepts

• Matter: Anything that has mass and occupies space.

• Energy: The capacity to do work or put matter into motion.

• Kinetic Energy: Energy in action, such as movement.

• Potential Energy: Stored (inactive) energy, such as energy stored in chemical bonds.

States of Matter

• Solid: Definite shape and volume.

• Liquid: Changeable shape, definite volume.

• Gas: Changeable shape and volume.

Forms of Energy in the Body

• Chemical energy: Stored in chemical bonds (e.g., food molecules).

• Electrical energy: Results from movement of charged particles (e.g., ions moving across cell membranes).

• Mechanical energy: Directly involved in moving matter (e.g., muscle contraction, pedaling a bicycle).

• Radiant (electromagnetic) energy: Energy that travels in waves (e.g., light, X-rays).

Elements and Atoms

Major and Trace Elements

• Four elements make up about 96% of the human body: carbon (C), hydrogen (H), oxygen (O), and nitrogen (N).

• Trace elements are required in small amounts for specific functions (e.g., iron for oxygen transport, iodine for thyroid hormones).

Atomic Structure

• Atoms: Smallest units of matter, composed of subatomic particles:

  • Protons: Positive charge (+), mass = 1 amu.

  • Neutrons: No charge, mass = 1 amu.

  • Electrons: Negative charge (–), negligible mass.

• Atomic number: Number of protons in the nucleus.

• Mass number: Sum of protons and neutrons.

• Isotopes: Atoms with the same number of protons but different numbers of neutrons.

• Atomic weight: Average mass of all isotopes of an element.

Radioisotopes

• Unstable isotopes that emit radiation; used in medical imaging and research.

• Can be harmful by damaging DNA.

Compounds, Mixtures, and Chemical Bonds

Compounds and Mixtures

• Compound: Two or more different atoms chemically bonded (e.g., H2O, CO2).

• Mixture: Two or more substances physically intermixed (not chemically bonded).

• Types of mixtures:

  • Solutions: Homogeneous mixtures (e.g., salt water).

  • Colloids: Heterogeneous mixtures with larger particles (e.g., cytoplasm).

  • Suspensions: Large particles that settle out (e.g., blood cells in plasma).

Chemical Bonds

• Ionic bonds: Transfer of electrons from one atom to another, forming ions (e.g., NaCl).

• Covalent bonds: Sharing of electrons between atoms.

  • Nonpolar covalent: Equal sharing (e.g., O2).

  • Polar covalent: Unequal sharing, creating partial charges (e.g., H2O).

• Hydrogen bonds: Weak attractions between a hydrogen atom and an electronegative atom (e.g., between water molecules).

Chemical Reactions

Types of Chemical Reactions

• Synthesis (Combination): Atoms or molecules combine to form a larger, more complex molecule.

• Decomposition: Molecule is broken down into smaller molecules or atoms.

• Exchange (Displacement): Involves both synthesis and decomposition; bonds are made and broken.

Energy in Chemical Reactions

• Exergonic reactions: Release energy (catabolic).

• Endergonic reactions: Absorb energy (anabolic).

Reaction Rates

• Factors affecting rate:

  • Temperature (higher = faster)

  • Concentration of reactants (higher = faster)

  • Particle size (smaller = faster)

  • Catalysts (e.g., enzymes) speed up reactions

Inorganic and Organic Compounds

Inorganic Compounds

• Water: Most abundant inorganic compound, about 60-80% of cell volume.

• Salts: Ionic compounds that dissociate into ions in water (e.g., NaCl, Ca2+).

• Acids: Release H+ ions in solution (proton donors).

• Bases: Release OH– ions in solution (proton acceptors).

• pH scale: Measures H+ concentration; 0-6.99 = acidic, 7 = neutral, 7.01-14 = basic.

Organic Compounds

• Contain carbon; include carbohydrates, lipids, proteins, and nucleic acids.

• Polymers: Large molecules made of repeating subunits (monomers).

Class of Organic Molecule	Monomers (Building Blocks)	Polymer
Carbohydrates	Monosaccharides (e.g., glucose)	Polysaccharides (e.g., starch, glycogen)
Proteins	Amino acids	Polypeptides or proteins
Nucleic acids	Nucleotides	DNA, RNA

Carbohydrates

• Major energy source for the body.

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

• Disaccharides: Two sugars joined (e.g., sucrose, lactose).

• Polysaccharides: Chains of sugars (e.g., starch, glycogen).

Lipids

• Insoluble in water; important for energy storage, insulation, and cell membranes.

• Triglycerides: Glycerol + 3 fatty acids; main energy storage lipid.

• Phospholipids: Glycerol + 2 fatty acids + phosphate group; major component of cell membranes.

• Steroids: Four interlocking rings; cholesterol is the most important steroid, precursor for hormones.

Proteins

• Polymers of amino acids; perform structural, enzymatic, transport, contractile, and defensive functions.

• Four structural levels:

  • Primary: Linear sequence of amino acids.

  • Secondary: How amino acids interact (e.g., alpha helix, beta sheet).

  • Tertiary: 3D shape of polypeptide.

  • Quaternary: How two or more polypeptides interact.

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

Nucleic Acids

• Polymers of nucleotides; store and transmit genetic information.

• DNA (Deoxyribonucleic Acid): Double helix; stores genetic information; bases: adenine (A), thymine (T), cytosine (C), guanine (G).

• RNA (Ribonucleic Acid): Single-stranded; involved in protein synthesis; bases: adenine (A), uracil (U), cytosine (C), guanine (G).

• Complementary base pairing: In DNA, A pairs with T, C pairs with G. In RNA, A pairs with U.

• Types of RNA:

  • mRNA: Messenger RNA; carries genetic code from DNA to ribosome.

  • tRNA: Transfer RNA; brings amino acids to ribosome during protein synthesis.

  • rRNA: Ribosomal RNA; forms part of ribosome structure.

ATP: The Energy Currency

• Adenosine Triphosphate (ATP): Main energy carrier in cells.

• Energy is released when ATP is hydrolyzed to ADP (adenosine diphosphate) and inorganic phosphate:

$\text{ATP} \rightarrow \text{ADP} + \text{P}_i + \text{energy}$

• ATP powers cellular work such as muscle contraction, active transport, and synthesis of macromolecules.

Summary Table: Key Terms and Definitions

Term	Definition
Matter	Anything that has mass and occupies space
Element	Substance that cannot be broken down by ordinary chemical means
Atom	Smallest unit of an element
Isotope	Atoms of the same element with different numbers of neutrons
Ion	Atom or molecule with a net electric charge
Compound	Two or more different atoms chemically bonded
Solution	Homogeneous mixture of two or more substances
Enzyme	Protein that acts as a biological catalyst

Additional info: Some explanations and examples have been expanded for clarity and completeness, based on standard Anatomy & Physiology curriculum.