Inorganic Compounds Essential to Human Functioning

Learning Objectives

  • By the end of this section, you will be able to:

    • Understand the chemistry of human life, focusing on compounds important for the body’s structure and function.

    • Differentiate between inorganic and organic compounds.

    • Examine the roles and importance of various inorganic compounds such as water, salts, acids, and bases.

Inorganic vs. Organic Compounds

Inorganic Compounds

  • Defined as substances that do not contain both carbon and hydrogen.

    • Examples:

      • Water (H2O)

      • Hydrochloric acid (HCl)

      • Carbon dioxide (CO2) is one of the few inorganic compounds containing carbon.

Organic Compounds

  • Substances that contain both carbon and hydrogen, formed via covalent bonds within living organisms.

    • Key elements: Carbon (C) and Hydrogen (H), which are abundant in the body, play critical roles in food and body structure.

Water

  • Constitutes up to 70% of an adult’s body weight, found in cells and between them in tissues.

Water as a Lubricant and Cushion

  • Lubrication:

    • Synovial fluid lubricates joints; pleural fluid assists lung expansion and recoil.

    • Ensures smooth movement of digestive organs.

  • Cushioning:

    • Protects cells and organs from physical trauma (e.g., cushions the brain).

    • Provides cushioning for a developing fetus.

Water as a Heat Sink

  • Absorbs heat generated by chemical reactions without significantly increasing temperature.

    • Maintains body temperature by facilitating sweating and heat transfer from core to skin.

Water as a Component of Liquid Mixtures

  • Mixtures contain substances maintaining their chemical identity, including:

    • Solutions: Homogeneous mixtures where solute is evenly distributed in solvent (e.g., sugar in water).

    • Colloids: Mixtures with larger particles that scatter light, making them opaque (e.g., milk, cream).

    • Suspensions: Heavier substances suspended temporarily, which settle over time (e.g., blood sedimentation).

Water's Role in Chemical Reactions

Dehydration Synthesis

  • Reactants release hydrogen and hydroxyl to form a product, producing a molecule of water.

Hydrolysis

  • A compound is disrupted by water, with water splitting into hydrogen and hydroxyl to break bonds.

  • Both reactions play an important role in organic chemistry.

Salts

  • Formed when ions bond ionically; dissociates in water into ions other than H+ or OH–.

    • Ions that dissociate are called electrolytes, crucial for nerve impulses and muscle contractions.

  • Example: Sodium chloride (NaCl) dissociates into Na+ and Cl- in water.

Acids and Bases

Acids

  • Substances releasing hydrogen ions (H+) in solutions.

    • Strong Acids: Completely dissociate (e.g., hydrochloric acid in the stomach).

    • Weak Acids: Partially dissociate (e.g., acetic acid in vinegar).

Bases

  • Substances releasing hydroxyl ions (OH–) or accepting H+.

    • Remove free H+ ions, reducing acidity.

pH Concept

  • Measures the acidity or alkalinity of a solution on a scale of 0 to 14.

    • Neutral: pH of 7 (pure water).

    • Acidic Solutions: pH < 7.

    • Basic Solutions: pH > 7.

Buffers

  • Solutions of weak acids and conjugate bases regulating pH levels in body fluids.

    • Keep blood pH between 7.35 to 7.45, vital for homeostasis and cellular functioning.

Homeostatic Imbalances

Acidosis

  • Excessive acidity due to poor breathing or metabolic issues, leading to excess CO2.

Alkalosis

  • Excessive alkalinity caused by respiratory issues or severe vomiting.

  • Homeostasis involves buffers, breathing regulation, and chemical excretion to maintain pH.