Chemistry Comes Alive: Foundations for Anatomy & Physiology

Chemistry Comes Alive

Matter

Matter is the fundamental substance that makes up all physical objects, including the human body. Understanding matter is essential for grasping the chemical basis of anatomy and physiology.

• Definition: Anything that has mass and occupies space.

• Weight: The pull of gravity on mass.

• States of Matter:

  • Solid: Definite shape and volume.

  • Liquid: Changeable shape; definite volume.

  • Gas: Changeable shape and volume.

Elements

Elements are the simplest forms of matter with unique chemical properties. They are the building blocks of all substances in the body.

• Definition: Substances that cannot be broken down by ordinary chemical methods.

• Properties:

  • Physical properties: Detectable by senses or measurable.

  • Chemical properties: Describe how atoms interact or bond with one another.

Atoms

Atoms are the smallest units of elements that retain their properties. They are the basic units of chemical structure.

• Atomic symbol: One- or two-letter shorthand for each element.

• Unique building blocks: Give each element its physical and chemical properties.

Major, Lesser, and Trace Elements of the Human Body

The human body is composed of a variety of elements, with four making up the majority of body mass.

• Major elements: Make up 96.1% of body mass.

• Lesser elements: Present in smaller amounts.

• Trace elements: Required in minute quantities, often as enzyme activators.

Mixtures and Compounds

Mixtures

Mixtures consist of two or more components physically intermixed, without chemical bonding.

• Types of mixtures:

  • Solutions: Homogeneous mixtures; solute particles are very small.

  • Colloids (Emulsions): Heterogeneous mixtures; solute particles do not settle out (e.g., cytosol).

  • Suspensions: Heterogeneous mixtures; large solute particles settle out (e.g., blood).

• Mixtures vs. Compounds:

  • Mixtures: No chemical bonding; can be separated by physical means.

  • Compounds: Chemical bonding; can only be separated by breaking bonds.

Solutions

Solutions are homogeneous mixtures where one substance (solute) is dissolved in another (solvent).

• Solvent: Substance present in greatest amount, usually a liquid.

• Solute: Substance present in smaller amounts.

• Concentration expressions:

  • Percent of solute in total solution.

  • Milligrams per deciliter (mg/dl).

  • Molarity (M): moles per liter.

Formula for Molarity:

$\text{Molarity (M)} = \frac{\text{moles of solute}}{\text{liters of solution}}$

Biochemistry: Inorganic and Organic Compounds

Inorganic Compounds

Inorganic compounds include water, salts, acids, and bases. They do not contain carbon (with exceptions).

• Water: Most abundant inorganic compound; 65–80% of cell volume.

• Properties of Water:

  • High heat capacity: Absorbs/releases heat with little temperature change.

  • High heat of vaporization: Evaporation requires large amounts of heat.

  • Polar solvent properties: Dissolves and dissociates ionic substances.

  • Reactivity: Necessary for hydrolysis and dehydration synthesis reactions.

  • Cushioning: Protects organs from physical trauma.

• Salts: Ionic compounds that dissociate into ions in water; important for body functions and homeostasis.

• Acids and Bases:

  • Acids: Release H+ ions (e.g., HCl, H2CO3).

  • Bases: Release OH- ions or accept H+ (e.g., NH3).

• pH Scale: Measures relative concentration of H+ ions.

Formula for pH:

$\text{pH} = -\log_{10}[H^+]$

• Acidic solutions: pH < 7

• Neutral solutions: pH = 7

• Alkaline (basic) solutions: pH > 7

Organic Compounds

Organic compounds contain carbon and are unique to living systems. They include carbohydrates, lipids, proteins, and nucleic acids.

• Polymers: Chains of similar units called monomers.

• Synthesized by: Dehydration synthesis.

• Broken down by: Hydrolysis reactions.

Carbohydrates

Structure and Function

Carbohydrates are sugars and starches that serve as major energy sources and structural molecules.

• General formula: (CH2O)n

• Classes:

  • Monosaccharides: One sugar (e.g., glucose, ribose).

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

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

• Functions:

  • Major source of cellular fuel (e.g., glucose).

  • Structural molecules (e.g., ribose in RNA).

Lipids

Structure and Function

Lipids are hydrophobic molecules that include fats, oils, and steroids. They are important for energy storage, insulation, and cell membrane structure.

• Main types:

  • Triglycerides (neutral fats): Energy storage, insulation, protection.

  • Phospholipids: Major component of cell membranes.

  • Steroids: Cholesterol, vitamin D, steroid hormones, bile salts.

  • Eicosanoids: Prostaglandins (involved in blood clotting, inflammation).

• Saturated fatty acids: Single covalent bonds; solid at room temperature.

• Unsaturated fatty acids: One or more double bonds; liquid at room temperature.

Proteins

Structure and Function

Proteins are polymers of amino acids and perform a vast array of functions in the body, including catalysis, transport, and structural support.

• Amino acids: 20 types; joined by peptide bonds.

• Protein denaturation: Loss of functional 3D shape due to pH or temperature changes.

• Functions: Enzymes, transport, structural, regulatory, and more.

Nucleic Acids

DNA and RNA

Nucleic acids store and transmit genetic information. DNA is double-stranded and found in the nucleus; RNA is single-stranded and functions in protein synthesis.

• Monomer: Nucleotide (composed of nitrogen base, pentose sugar, phosphate group).

• DNA bases: Adenine (A), Guanine (G), Cytosine (C), Thymine (T).

• RNA bases: Adenine (A), Guanine (G), Cytosine (C), Uracil (U).

• Base pairing: A with T (DNA), G with C.

• Structure: Double helix (DNA), single strand (RNA).

Adenosine Triphosphate (ATP)

ATP is the energy currency of the cell, providing energy for cellular processes.

• Structure: Adenine-containing RNA nucleotide with two additional phosphate groups.

• Function: Powers chemical reactions in cells via phosphorylation.

ATP Hydrolysis Equation:

$\text{ATP} + \text{H}_2\text{O} \rightarrow \text{ADP} + \text{P}_i + \text{energy}$

Summary Table: Classes of Compounds

Class	Main Elements	Examples	Functions
Inorganic	Usually lack carbon	Water, salts, acids, bases	Solvent, electrolytes, pH balance
Organic	Contain carbon	Carbohydrates, lipids, proteins, nucleic acids	Energy, structure, catalysis, genetic information

Additional info:

• These notes provide foundational chemistry concepts essential for understanding physiological processes in the human body.

• Key terms such as monomer, polymer, denaturation, and phosphorylation are central to biochemistry in anatomy and physiology.