Foundations of Chemistry and Cell Biology in Anatomy & Physiology

Chemistry

Basic Chemistry Terminology

Chemistry is fundamental to understanding Anatomy & Physiology, as it explains the molecular basis of life. Mastery of basic chemical terms and concepts is essential for further study.

• Key Terms: Atom, element, atom, proton, neutron, electron, ion, isotope, etc.

• Types of Chemical Bonds:

  • Covalent bonds: Atoms share electrons.

  • Ionic bonds: Atoms transfer electrons, forming charged ions.

  • Hydrogen bonds: Weak attractions between polar molecules.

• Chemical Reactions:

  • Involve making or breaking chemical bonds.

  • May release or require energy.

  • Activation energy: The minimum energy required to start a reaction.

  • Increasing reaction rate: Can be achieved by increasing temperature, concentration, or using catalysts (enzymes).

Properties of Inorganic Compounds

Inorganic compounds, such as water, acids, bases, and salts, play vital roles in physiological processes.

• Water:

  • Excellent solvent, high heat capacity, high heat of vaporization, cushioning properties.

• Acids:

  • Release hydrogen ions (H+) in solution.

  • Form negative ions called anions.

• Bases:

  • Accept hydrogen ions or release hydroxide ions (OH-).

  • Form positive ions called cations.

• Salts:

  • Ionic compounds that dissociate in water but do not release H+ or OH-.

• pH Scale:

  • Measures acidity or alkalinity of a solution.

  • pH < 7: Acidic; pH = 7: Neutral; pH > 7: Basic (alkaline).

  • Decreasing pH = increasing acidity; increasing pH = increasing alkalinity.

Properties of Organic Compounds

Organic compounds are carbon-based molecules essential for life. They include carbohydrates, lipids, proteins, and nucleic acids.

• Monomers and Polymers: Monomers are building blocks; polymers are long chains of monomers.

• Dehydration Synthesis: Joins monomers by removing water.

• Hydrolysis: Breaks polymers into monomers by adding water.

• Carbohydrates:

  • Include monosaccharides, disaccharides, and polysaccharides.

  • Polysaccharides (e.g., starch, glycogen) are storage forms of energy in plants and animals.

• Lipids:

  • Triglycerides: Neutral fats; can be saturated (solid at room temperature) or unsaturated (liquid at room temperature). Used for long-term energy storage and insulation.

  • Phospholipids: Major components of cell membranes.

  • Steroids: Include cholesterol, vitamin D, and hormones.

• Proteins (Polypeptides):

  • Composed of amino acids linked by peptide bonds.

  • Levels of Organization: Primary, secondary, tertiary, and quaternary structures.

  • Categories: Fibrous (structural) and globular (functional) proteins.

  • Enzymes: Biological catalysts that speed up reactions by lowering activation energy. Three steps: substrate binding, transition state, and product release.

• Nucleic Acids:

  • DNA and RNA store and transmit genetic information.

  • ATP (adenosine triphosphate) is the primary energy carrier in cells.

Cytology

Plasma Membrane

The plasma membrane is a selectively permeable barrier that surrounds the cell, maintaining homeostasis and mediating communication with the environment.

• General Functions: Protects the cell, controls entry and exit of substances, facilitates communication.

• Structure:

  • Phospholipid bilayer with hydrophilic (water-attracting) heads facing outward and hydrophobic (water-repelling) tails facing inward.

• Types of Proteins in the Plasma Membrane:

  • Integral proteins: Span the membrane and are involved in transport.

  • Peripheral proteins: Attached to the membrane surface, involved in signaling and structure.

• Types of Cell Junctions:

  • Tight junctions: Prevent leakage between cells.

  • Desmosomes: Provide mechanical strength by anchoring cells together.

  • Gap junctions: Allow communication between cells via small channels.

• Membrane Transport Mechanisms:

  • Passive Transport: Does not require energy.

    • Simple diffusion: Movement of molecules from high to low concentration.

    • Facilitated diffusion: Movement via carrier or channel proteins.

  • Active Transport: Requires energy (usually ATP).

    • Primary active transport: Direct use of ATP to move substances.

    • Secondary active transport: Uses energy from gradients created by primary transport.

    • Vesicular transport: Endocytosis (into cell) and exocytosis (out of cell).

Table: Comparison of Membrane Transport Mechanisms

Type	Energy Required?	Direction	Examples
Simple Diffusion	No	High to Low	O2, CO2
Facilitated Diffusion	No	High to Low	Glucose, ions
Primary Active Transport	Yes (ATP)	Low to High	Na+/K+ pump
Vesicular Transport	Yes (ATP)	Varies	Endocytosis, exocytosis

Example: The sodium-potassium pump ($Na^+/K^+$ ATPase) is a classic example of primary active transport, moving sodium ions out of and potassium ions into the cell against their concentration gradients using ATP.

Additional info: Some explanations and examples have been expanded for clarity and completeness based on standard Anatomy & Physiology curricula.