Biochemistry in Anatomy & Physiology

Introduction to Biochemistry

Biochemistry is the study of the chemical composition and reactions of living matter. It is essential for understanding how the body maintains homeostasis, processes nutrients, and generates energy.

• Homeostasis: The maintenance of stable internal conditions, including water and salt balance.

• Metabolism: All chemical reactions in the body, including synthesis (anabolism) and breakdown (catabolism) of molecules.

• Biomolecules: Carbohydrates, lipids, proteins, and nucleic acids are the main classes of organic compounds in living organisms.

Major Chemical Classes in Living Matter

Organic Compounds

Organic compounds contain carbon and are typically large, complex molecules. They are essential for structure and function in living organisms.

• Carbohydrates: Provide energy and structural support.

• Lipids: Store energy, form cell membranes, and act as signaling molecules.

• Proteins: Serve as enzymes, structural components, and signaling molecules.

• Nucleic Acids: Store and transmit genetic information (DNA and RNA).

Inorganic Compounds

Inorganic compounds do not contain carbon-hydrogen bonds. Water, salts, acids, and bases are the most important inorganic compounds in the body.

• Water: The most abundant inorganic compound, making up 60-80% of the volume of living cells.

• Salts: Ionic compounds that dissociate in water to form electrolytes, which are essential for nerve and muscle function.

• Acids and Bases: Substances that release hydrogen ions (H+) or hydroxide ions (OH-) in solution, respectively.

Properties and Functions of Water

Importance of Water in the Body

Water is vital for life due to its unique properties:

• High Heat Capacity: Absorbs and releases large amounts of heat with little temperature change, helping to maintain body temperature.

• High Heat of Vaporization: Evaporation of water requires significant energy, providing a cooling effect (e.g., sweating).

• Reactivity: Water is involved in hydrolysis and dehydration synthesis reactions.

• Cushioning: Protects organs from physical trauma (e.g., cerebrospinal fluid cushions the brain and spinal cord).

Polar Solvent Properties

Water's polarity makes it an excellent solvent, allowing it to dissolve and transport many substances in the body.

• Solvent: Dissolves ionic and polar substances, forming solutions.

• Transport: Facilitates movement of nutrients, gases, and wastes in the body.

Salts, Acids, and Bases

Salts

Salts are ionic compounds that dissociate in water to form ions. These ions (electrolytes) are essential for physiological processes.

• Electrolytes: Conduct electrical currents in solution, crucial for nerve impulse transmission and muscle contraction.

• Examples: Sodium chloride (NaCl), potassium chloride (KCl), calcium phosphate (Ca3(PO4)2).

Acids and Bases

Acids and bases are substances that affect the concentration of hydrogen ions in solution.

• Acids: Proton donors; release H+ ions in solution. Example: Hydrochloric acid (HCl).

• Bases: Proton acceptors; release OH- ions or accept H+ ions. Example: Sodium hydroxide (NaOH).

pH and Acid-Base Balance

The pH scale measures the concentration of hydrogen ions in a solution, indicating its acidity or alkalinity.

• pH Scale: Ranges from 0 (most acidic) to 14 (most basic), with 7 being neutral.

• Formula:

• Buffers: Substances that minimize changes in pH by accepting or donating H+ ions. Important for maintaining homeostasis in body fluids.

Summary Table: Properties of Water

Key Terms and Definitions

• Electrolyte: A substance that conducts electricity when dissolved in water.

• Buffer: A compound that stabilizes pH by neutralizing acids or bases.

• Hydrolysis: A chemical reaction that breaks bonds by adding water.

• Dehydration Synthesis: A reaction that forms bonds by removing water.

Applications in Anatomy & Physiology

• Understanding biochemistry is essential for grasping how the body maintains homeostasis, processes nutrients, and responds to changes in the environment.

• Electrolyte balance is critical for nerve and muscle function.

• Acid-base balance is vital for enzyme activity and metabolic processes.