Basic Chemistry Concepts for Anatomy & Physiology

Basic Chemistry Concepts in Anatomy & Physiology

This section introduces foundational chemistry concepts essential for understanding physiological processes in the human body. Mastery of these topics is crucial for success in Anatomy & Physiology courses.

Major Body Elements

The human body is composed primarily of a few key elements that are vital for life and physiological function.

• Oxygen (O): Essential for cellular respiration and energy production.

• Carbon (C): The backbone of all organic molecules, including carbohydrates, lipids, proteins, and nucleic acids.

• Hydrogen (H): Found in water and most organic compounds; involved in acid-base balance.

• Nitrogen (N): A component of amino acids, proteins, and nucleic acids.

• Calcium (Ca), Phosphorus (P), Potassium (K), Sulfur (S), Sodium (Na), Chlorine (Cl), Magnesium (Mg), Iron (Fe): Present in smaller amounts but essential for various physiological processes.

Example: Calcium is critical for muscle contraction and nerve function.

Atomic Structure: Protons, Neutrons, Electrons, Atomic Weight

Atoms are the smallest units of matter, consisting of subatomic particles.

• Protons: Positively charged particles found in the nucleus.

• Neutrons: Neutral particles also located in the nucleus.

• Electrons: Negatively charged particles orbiting the nucleus in electron shells.

• Atomic Number: Number of protons in an atom, determines the element.

• Atomic Weight (Mass Number): Sum of protons and neutrons in the nucleus.

Example: Carbon has 6 protons, 6 neutrons, and 6 electrons; its atomic number is 6, and its atomic weight is approximately 12.

Molecules: Solution, Colloid, Suspension

Molecules can combine to form mixtures with different properties, important for physiological processes.

• Solution: A homogeneous mixture where solutes are completely dissolved in a solvent (e.g., salt water).

• Colloid: A mixture with larger particles that do not settle out (e.g., cytoplasm).

• Suspension: A heterogeneous mixture with large particles that settle over time (e.g., blood cells in plasma).

Example: Blood is a suspension because blood cells can settle if left undisturbed.

Chemical Bonds: Covalent, Ionic, Polar, etc.

Chemical bonds hold atoms together in molecules and compounds, influencing their properties and functions.

• Covalent Bonds: Atoms share electron pairs (e.g., H2O).

• Ionic Bonds: Electrons are transferred from one atom to another, creating charged ions (e.g., NaCl).

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

• Nonpolar Covalent Bonds: Equal sharing of electrons (e.g., O2).

Example: The bond between sodium and chloride in table salt is ionic.

Factors Influencing the Rate of Chemical Reactions

The speed of chemical reactions in the body is affected by several factors, which are crucial for metabolic regulation.

• Temperature: Higher temperatures generally increase reaction rates.

• Concentration of Reactants: Higher concentrations lead to more frequent collisions and faster reactions.

• Particle Size: Smaller particles react faster due to greater surface area.

• Catalysts: Substances (often enzymes) that speed up reactions without being consumed.

Example: Enzymes in the digestive system act as catalysts to speed up the breakdown of food.

Acids, Bases, and pH

Acids and bases are substances that affect the hydrogen ion concentration in solutions, measured by the pH scale.

• Acid: Releases hydrogen ions (H+) in solution; pH less than 7.

• Base: Accepts hydrogen ions or releases hydroxide ions (OH-); pH greater than 7.

• pH Scale: Ranges from 0 (most acidic) to 14 (most basic); 7 is neutral.

Formula:

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

Example: Blood has a normal pH of about 7.4, which is slightly basic.