Fundamentals of Chemistry for Anatomy & Physiology

Chemistry in Anatomy & Physiology

Structure of Matter

Chemistry is the science that deals with the structure of matter, which is essential for understanding the biological processes in Anatomy & Physiology. Matter is anything that occupies space and has mass.

• Atom: The smallest stable unit of matter, composed of subatomic particles.

• Subatomic Particles: Protons (p+, positively charged), Neutrons (n0, neutral), Electrons (e-, negatively charged).

• Atomic Number: The number of protons in an atom, unique for each element.

• Mass Number: The sum of protons and neutrons in the nucleus.

• Isotopes: Atoms of the same element with different numbers of neutrons.

• Radioisotopes: Unstable isotopes that emit radiation as they decay.

• Atomic Mass: The average mass of an atom, accounting for isotopes.

• Mole: The amount of a substance containing Avogadro's number ($6.022 \times 10^{23}$) of particles.

Example: Carbon-12 and Carbon-14 are isotopes of carbon, differing in the number of neutrons.

Electron Shells and Chemical Bonds

Electrons occupy energy levels (shells) around the nucleus. The arrangement of electrons determines the chemical properties of an atom.

• Valence Shell: The outermost electron shell; atoms are most stable when this shell is full.

• Ionic Bonds: Formed by the transfer of electrons from one atom to another, resulting in oppositely charged ions (cations and anions) that attract each other.

• Covalent Bonds: Formed by the sharing of electron pairs between atoms.

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

• Hydrogen Bonds: Weak attractions between the partial positive charge of hydrogen in one polar molecule and the partial negative charge of another atom (e.g., oxygen or nitrogen).

Example: Water (H2O) molecules are held together by hydrogen bonds, giving water its unique properties.

Chemical Reactions in the Body

Types of Chemical Reactions

Chemical reactions are essential for life, allowing the body to build, break down, and transform molecules.

• Decomposition Reactions: Break down molecules into smaller components (e.g., hydrolysis: AB → A + B).

• Synthesis Reactions: Combine smaller molecules to form larger ones (e.g., dehydration synthesis: A + B → AB + H2O).

• Exchange Reactions: Involve both synthesis and decomposition (e.g., AB + CD → AD + CB).

• Reversible Reactions: Can proceed in both directions until equilibrium is reached (e.g., A + B ⇌ AB).

Example: The breakdown of glucose during cellular respiration is a decomposition reaction.

Enzymes and Activation Energy

Enzymes are biological catalysts that speed up chemical reactions by lowering the activation energy required.

• Exergonic Reactions: Release energy (e.g., catabolic reactions).

• Endergonic Reactions: Require energy input (e.g., anabolic reactions).

• Enzymes are specific to substrates and function in a series of steps (metabolic pathways).

Example: Digestive enzymes break down food molecules into absorbable units.

Inorganic and Organic Compounds

Inorganic Compounds

Inorganic compounds are essential for physiological processes and include water, acids, bases, and salts.

• Water (H2O): The most abundant compound in the body; excellent solvent, high heat capacity, participates in chemical reactions.

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

• Bases: Accept hydrogen ions or release hydroxide ions (OH-); proton acceptors.

• Salts: Ionic compounds that dissociate into cations and anions in water.

• pH Scale: Measures the concentration of H+ in solution; ranges from 0 (acidic) to 14 (basic), with 7 being neutral.

Example: Blood pH is tightly regulated around 7.4 for proper physiological function.

Properties of Water

• Solvent: Dissolves many substances, facilitating chemical reactions.

• Reactivity: Participates in hydrolysis and dehydration synthesis.

• High Heat Capacity: Absorbs and releases heat slowly, helping regulate body temperature.

• Lubrication: Reduces friction between body surfaces.

Electrolytes

• Electrolytes: Substances that dissociate into ions in solution, conducting electricity (e.g., NaCl, KCl).

• Importance: Essential for nerve impulse transmission, muscle contraction, and fluid balance.

Organic Compounds

Carbohydrates

Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen, serving as a primary energy source.

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

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

• Polysaccharides: Long chains of monosaccharides (e.g., glycogen, starch, cellulose).

Example: Glycogen is the main storage form of glucose in animals.

Lipids

Lipids are hydrophobic molecules important for energy storage, insulation, and cell membrane structure.

• Fatty Acids: Long hydrocarbon chains with a carboxyl group.

• Triglycerides: Glycerol + 3 fatty acids; main form of stored energy.

• Phospholipids: Major component of cell membranes; contain a phosphate group.

• Steroids: Four-ring structure; includes cholesterol, hormones.

Proteins

Proteins are polymers of amino acids, essential for structure, function, and regulation of tissues and organs.

• Amino Acids: Building blocks of proteins; 20 different types.

• Peptide Bonds: Covalent bonds linking amino acids.

• Levels of Structure: Primary (sequence), secondary (folding), tertiary (3D shape), quaternary (multiple polypeptides).

• Functions: Enzymes, structural support, transport, signaling, immune response.

Example: Hemoglobin is a protein that transports oxygen in the blood.

Nucleic Acids

Nucleic acids store and transmit genetic information.

• DNA (Deoxyribonucleic Acid): Double helix; stores genetic instructions.

• RNA (Ribonucleic Acid): Single-stranded; involved in protein synthesis.

• Nucleotides: Building blocks composed of a sugar, phosphate group, and nitrogenous base.

Example: ATP (adenosine triphosphate) is a nucleotide that stores and transfers energy in cells.

Table: Comparison of Major Organic Molecules

Type	Monomer	Main Function	Example
Carbohydrates	Monosaccharides	Energy source	Glucose, Glycogen
Lipids	Fatty acids, Glycerol	Energy storage, Membranes	Triglycerides, Phospholipids
Proteins	Amino acids	Structure, Enzymes	Hemoglobin, Collagen
Nucleic Acids	Nucleotides	Genetic information	DNA, RNA, ATP

Additional info:

• Some context and terminology were inferred based on standard Anatomy & Physiology chemistry content, as the original notes were fragmented and partially illegible.

• Key definitions, examples, and table structure were expanded for clarity and completeness.