Basic Chemistry for Anatomy & Physiology

Matter and Energy

Understanding matter and energy is fundamental to the study of anatomy and physiology, as all biological processes are governed by chemical principles.

• Matter: Anything that occupies space and has mass. Exists in three states:

  • Solid: Definite shape and volume

  • Liquid: Definite volume, takes shape of container

  • Gas: Neither definite shape nor volume

• Physical Changes: Alter state (solid, liquid, gas) without changing chemical composition.

• Chemical Changes: Alter the chemical composition of a substance.

• Energy: The ability to do work; exists as kinetic (active) or potential (stored).

• Forms of Energy:

  • Chemical: Stored in bonds (e.g., ATP)

  • Electrical: Movement of charged particles

  • Mechanical: Directly moves matter

  • Radiant: Travels in waves (electromagnetic spectrum)

Composition of Matter

All living things are composed of elements and atoms, which are the basic units of matter.

• Elements: Fundamental units of matter; 96% of the human body is made from oxygen, carbon, hydrogen, and nitrogen.

• Atoms: Building blocks of elements; each atom is unique to its element.

• Atomic Symbol: Chemical shorthand for each element.

Subatomic Particles

Atoms are composed of three main subatomic particles, which determine their chemical properties.

• Protons: Positively charged

• Neutrons: Neutral

• Electrons: Negatively charged

• Atoms are electrically neutral when protons equal electrons.

• Ions: Atoms that have lost or gained electrons, resulting in a charge.

Atomic Weights and Isotopes

Isotopes are variants of elements with different numbers of neutrons. Some isotopes are radioactive and are used in medical tracing.

• Isotopes: Same number of protons/electrons, different neutrons.

• Radioisotopes: Unstable, undergo spontaneous decay (radioactivity).

Molecules and Compounds

Molecules are formed when atoms combine chemically. Compounds are molecules made from different elements.

• Molecule: Two or more atoms of the same element combined chemically.

• Compound: Two or more atoms of different elements combined chemically.

• Chemical Equation: Represents reactants and products.

Chemical Bonds and Reactions

Chemical bonds are formed by interactions among electrons. Chemical reactions involve the making or breaking of these bonds.

• Electron Shells: Energy levels where electrons reside.

• Valence Shell: Outermost shell; stability achieved with 8 electrons.

• Reactive Elements: Atoms with incomplete valence shells; tend to gain, lose, or share electrons.

Types of Chemical Bonds

• Ionic Bonds: Electrons are transferred; forms ions (cations and anions).

• Covalent Bonds: Electrons are shared; can be single, double, nonpolar (equal sharing), or polar (unequal sharing).

• Hydrogen Bonds: Weak bonds; important in water and protein structure.

Patterns of Chemical Reactions

• Synthesis: Building larger molecules; energy absorbed.

• Decomposition: Breaking down molecules; energy released.

• Exchange: Both synthesis and decomposition.

• Most reactions are reversible.

Biochemistry: Chemical Composition of Living Matter

Biochemistry distinguishes between inorganic and organic compounds, both essential for life.

• Inorganic Compounds: Lack carbon; include water, salts, acids, bases.

• Organic Compounds: Contain carbon; include carbohydrates, lipids, proteins, nucleic acids.

Water

• Most abundant inorganic compound; vital for heat capacity, solvent properties, chemical reactivity, and cushioning.

• Hydrolysis: Water used to break bonds.

• Dehydration Synthesis: Water removed to form bonds.

Salts, Acids, and Bases

• Salts: Ionic compounds; dissociate in water; vital for nerve function.

• Electrolytes: Ions that conduct electricity.

• Acids: Release hydrogen ions; proton donors.

• Bases: Release hydroxyl ions; proton acceptors.

• pH Scale: Measures hydrogen ion concentration; ranges from 0 (acidic) to 14 (basic), 7 is neutral.

• Buffers: Regulate pH changes.

Organic Compounds

Organic compounds are large molecules essential for structure and function in the body.

Carbohydrates

• Contain carbon, hydrogen, oxygen; include sugars and starches.

• Monosaccharides: Simple sugars; single-ring structures (e.g., glucose).

• Disaccharides: Two monosaccharides joined by dehydration synthesis (e.g., sucrose).

• Polysaccharides: Long chains; storage molecules (e.g., starch, glycogen).

Lipids

• Include triglycerides, phospholipids, steroids.

• Insoluble in water; soluble in other lipids.

• Triglycerides: Energy storage; composed of fatty acids and glycerol.

• Saturated Fats: Single bonds; solid at room temperature.

• Unsaturated Fats: Double bonds; liquid at room temperature.

• Trans Fats: Hydrogenated oils; increase heart disease risk.

• Omega-3 Fatty Acids: Heart healthy.

• Phospholipids: Form cell membranes; hydrophilic head, hydrophobic tails.

• Steroids: Include cholesterol, hormones.

Proteins

• Account for over half of body’s organic matter; built from amino acids.

• Structural Levels:

  • Primary: Amino acid sequence

  • Secondary: Twisting/bending (alpha helix, beta sheet)

  • Tertiary: Globular structure

  • Quaternary: Multiple polypeptide chains

• Fibrous Proteins: Structural (e.g., collagen, keratin)

• Globular Proteins: Functional (e.g., enzymes, antibodies)

• Enzymes: Biological catalysts; increase reaction rates; names end in -ase.

Nucleic Acids

• Form genes; composed of nucleotides (nitrogenous base, pentose sugar, phosphate group).

• DNA: Double-stranded helix; contains genetic instructions.

• RNA: Single-stranded; carries out DNA instructions; types include mRNA, tRNA, rRNA.

Adenosine Triphosphate (ATP)

• Cellular energy molecule; composed of ribose, adenine, and three phosphate groups.

• Energy released by breaking phosphate bonds.

• ATP is replenished by oxidation of food fuels.

Summary Table: Common Elements in the Human Body

Additional info: This summary table is inferred from textbook context and typical content for Anatomy & Physiology.