Chemistry Fundamentals for Anatomy & Physiology: Mixtures, Chemical Reactions, and Macromolecules

Chemistry in Anatomy & Physiology

This chapter introduces foundational chemistry concepts essential for understanding biological processes in Anatomy & Physiology. It covers mixtures, chemical reactions, the role of water and electrolytes in homeostasis, and the structure and function of major biological macromolecules.

Mixtures

Definition and Types of Mixtures

• Mixture: Any substance containing two or more components physically intermixed.

• Mixtures are classified based on the uniformity and particle size of their components.

Types of Mixtures

• Solutions: Homogeneous mixtures with very small particles that do not settle out.

  • Solvent: The dissolving medium (e.g., water is the body's primary solvent).

  • Solute: The substance dissolved in the solvent (e.g., NaCl in saline solution).

• Colloids: Heterogeneous mixtures with larger particles that do not settle out.

  • Can undergo sol-gel transformation (e.g., cytosol of cells changes consistency during cell division).

• Suspensions: Heterogeneous mixtures with large particles that do settle out (e.g., blood, where cells are suspended in plasma).

Concentration of Solutions

• Percent Solution: Amount of solute dissolved, expressed as a percentage of the total solution volume.

• Molarity (mol/L): Number of moles of a substance per liter of solution.

  • Mole: The amount of any element or compound equal to its atomic or molecular weight in grams.

Formula for Molarity:

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

Chemical Reactions

Types of Chemical Reactions

• Synthesis Reaction: Formation of bonds between atoms or molecules to create larger, more complex structures.

  • Example: Anabolic reactions in the body (e.g., protein synthesis).

  • General equation: $A + B \rightarrow AB$

• Decomposition Reaction: Bonds are broken to create smaller molecules or individual atoms.

  • Example: Catabolic reactions in the body (e.g., digestion of food).

  • General equation: $AB \rightarrow A + B$

Inorganic Compounds & Their Role in Homeostasis

Water

• Universal Solvent: Water dissolves and transports nutrients, gases, and wastes. It surrounds charged structures, facilitating interactions.

• High Heat Capacity: Water absorbs and releases large amounts of heat with minimal temperature change, helping maintain body temperature.

• Cushioning: Water-based fluids protect internal organs from physical trauma.

• High Heat of Vaporization: Large amounts of heat are required to convert water from liquid to gas, aiding in cooling (e.g., sweating).

• Reactivity: Water participates in chemical reactions such as hydrolysis (breaking bonds with water) and dehydration synthesis (forming bonds by removing water).

Salts, Acids, and Bases

• Salts: Ionic compounds that dissociate in water to form electrolytes (e.g., Na+, K+, Fe2+), essential for muscle contraction, nerve impulse transmission, and oxygen transport.

• Acids: Substances that release H+ ions in solution, lowering pH.

• Bases: Substances that release OH- ions in solution, raising pH.

• Normal blood pH: 7.35–7.45 (slightly basic).

Buffers

• Problem: High or low pH disrupts cellular activity and damages proteins.

• Buffers: Systems that resist abrupt changes in pH by releasing or binding H+ ions.

  • Weak acids: Release some (but not all) H+ ions when pH rises.

  • Weak bases: Bind excess H+ ions when pH falls.

  • Result: Buffers prevent large pH changes that could cause cellular damage.

Organic Compounds & Homeostasis

Carbon and Macromolecules

• Most molecules in the body contain carbon, which is electroneutral (neither gains nor loses electrons).

• Carbon forms molecules of various shapes (chains, rings) that serve diverse biological functions.

• Macromolecules: Large polymers made of repeating subunits called monomers.

Types of Macromolecules

Carbohydrates

• Definition: Sugars and starches that serve as a primary energy source.

• Monomer: Monosaccharide (e.g., glucose, fructose, galactose).

• Monosaccharides can combine to form disaccharides and polysaccharides.

• Functions:

  • Provide an easy-to-use energy source for cells.

  • Participate in cell interactions and communication (e.g., carbohydrates on cell surfaces).

Lipids

• Definition: Diverse group of hydrophobic molecules including fats, oils, and steroids.

• Monomers: Fatty acids and glycerol.

• Types of Triglycerides:

  • Saturated: Only single covalent bonds; solid at room temperature (e.g., animal fats).

  • Unsaturated: One or more double bonds; liquid at room temperature (e.g., plant oils).

  • Trans fats: Unsaturated fats chemically altered to add hydrogen (e.g., processed foods).

  • Omega-3 fatty acids: Found in cold-water fish; beneficial for heart health.

• Functions: Protection, insulation, and energy storage.

• Phospholipids: Major component of cell membranes; have hydrophilic heads and hydrophobic tails.

• Steroids: Include cholesterol, a structural component of membranes and precursor to steroid hormones.

Proteins

• Monomer: Amino acids.

• Structure: Sequence of amino acids determines protein shape and function.

• Types:

  • Fibrous proteins: Long, strand-like; provide support and strength (e.g., collagen, muscle fibers).

  • Globular proteins: Compact, spherical; chemically active (e.g., enzymes, antibodies, hormones).

• Enzymes: Biological catalysts that lower activation energy and speed up chemical reactions. Highly specific for their substrates.

Nucleic Acids and ATP

• ATP (Adenosine Triphosphate): The primary energy-transferring molecule in cells.

• ATP stores energy in its phosphate bonds; when a phosphate is transferred to another molecule, energy is released for cellular work.

• Without ATP, essential cellular processes cease, leading to cell death.

ATP Hydrolysis Equation:

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

Summary Table: Types of Mixtures

Type	Particle Size	Settling	Example
Solution	Very small	No	Saline (NaCl in water)
Colloid	Intermediate	No	Cytosol
Suspension	Large	Yes	Blood (cells in plasma)

Additional info: This guide expands on the original notes by providing definitions, examples, and context for each concept, ensuring a comprehensive understanding for Anatomy & Physiology students.