Foundations of Chemistry and Cell Biology for Anatomy & Physiology

Chemistry Fundamentals in Anatomy & Physiology

Basic Chemistry Terminology

Chemistry provides the foundation for understanding biological processes in Anatomy & Physiology. Key terms and concepts are essential for describing matter and its interactions in living systems.

• Matter: Anything that has mass and occupies space. Examples include solids, liquids, and gases.

• Elements: Pure substances consisting of only one type of atom (e.g., Oxygen, Carbon).

• Atoms: The smallest units of elements, composed of protons, neutrons, and electrons.

• Proton: Positively charged particle in the nucleus.

• Neutron: Neutral particle in the nucleus.

• Electron: Negatively charged particle orbiting the nucleus.

• Ion: Atom or molecule with a net electric charge due to loss or gain of electrons.

• Isotope: Atoms of the same element with different numbers of neutrons.

Mixtures and Their Properties

Mixtures are combinations of two or more substances that retain their individual properties. There are three main types:

• Solutions: Homogeneous mixtures where solutes are dissolved in solvents (e.g., salt water).

• Colloids: Heterogeneous mixtures with larger particles that do not settle (e.g., cytoplasm).

• Suspensions: Heterogeneous mixtures with particles that settle out over time (e.g., blood cells in plasma).

Chemical Bonds

Chemical bonds hold atoms together in molecules and compounds. The main types are:

• Ionic Bonds: Formed by the transfer of electrons from one atom to another, resulting in oppositely charged ions (e.g., NaCl).

• Covalent Bonds: Formed by the sharing of electrons between atoms (e.g., H2O).

• Hydrogen Bonds: Weak attractions between polar molecules, important in water and DNA structure.

Chemical Reactions

Chemical reactions involve the making and breaking of bonds, resulting in new substances.

• Types of Reactions: Synthesis, decomposition, exchange, and reversible reactions.

• Energy Release: Exergonic reactions release energy; endergonic reactions absorb energy.

• Rate of Reaction: Influenced by temperature, concentration, particle size, and catalysts.

Properties of Inorganic Compounds

Inorganic compounds are essential for physiological processes. Key examples include water, acids, bases, and salts.

• Water: Universal solvent, high heat capacity, high heat of vaporization, provides cushioning.

• Acids: Release H+ ions in solution; pH < 7.

• Bases: Release OH- ions or accept H+; pH > 7.

• Salts: Ionic compounds that dissociate into ions other than H+ or OH-.

pH Scale: Measures hydrogen ion concentration. Acidic solutions have more H+, basic solutions have more OH-, and neutral solutions have equal amounts.

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

Organic Compounds in Physiology

Monomers, Polymers, and Reactions

Organic compounds are built from monomers joined to form polymers through dehydration synthesis; hydrolysis breaks them down.

• Monomer: Single subunit (e.g., glucose).

• Polymer: Chain of monomers (e.g., starch).

• Dehydration Synthesis: Removal of water to join monomers.

• Hydrolysis: Addition of water to break polymers into monomers.

Carbohydrates

Carbohydrates are energy sources and structural components.

• Monosaccharides: Simple sugars (e.g., glucose).

• Disaccharides: Two monosaccharides joined (e.g., sucrose).

• Polysaccharides: Long chains (e.g., glycogen in animals, starch in plants).

• Storage: Animals store carbohydrates as glycogen; plants as starch.

Lipids

Lipids are hydrophobic molecules important for energy storage, insulation, and cell membranes.

• Triglycerides: Neutral fats; composed of glycerol and three fatty acids.

• Saturated vs. Unsaturated: Saturated fats have no double bonds; unsaturated have one or more, affecting fluidity.

• Phospholipids: Form cell membranes; have polar heads and nonpolar tails.

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

Proteins (Polypeptides)

Proteins perform structural, enzymatic, and regulatory functions.

• Levels of Organization:

  • Primary: Sequence of amino acids

  • Secondary: Alpha helices and beta sheets

  • Tertiary: 3D folding

  • Quaternary: Multiple polypeptide chains

• Fibrous Proteins: Structural (e.g., collagen).

• Globular Proteins: Functional (e.g., enzymes).

• Enzymes: Biological catalysts; lower activation energy. Three steps: substrate binding, transition state, product release.

Nucleic Acids

Nucleic acids store and transmit genetic information.

• DNA: Deoxyribonucleic acid; genetic blueprint.

• RNA: Ribonucleic acid; involved in protein synthesis.

• ATP: Adenosine triphosphate; energy currency of the cell.

ATP Function: Provides energy for cellular processes by hydrolysis.

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

Cell Biology (Cytology)

Plasma Membrane

The plasma membrane is a selectively permeable barrier that regulates the movement of substances into and out of the cell.

• General Functions: Protection, communication, transport, and cell recognition.

• Structure: Phospholipid bilayer with hydrophilic heads facing outward and hydrophobic tails inward.

• Membrane Proteins: Integral and peripheral proteins serve as channels, carriers, receptors, and enzymes.

Cell Junctions

Cell junctions connect cells and facilitate communication.

• Tight Junctions: Prevent leakage between cells.

• Desmosomes: Provide mechanical strength.

• Gap Junctions: Allow passage of ions and small molecules.

Membrane Transport

Transport across the plasma membrane is essential for maintaining homeostasis.

• Passive Transport: No energy required.

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

  • Facilitated Diffusion: Uses carrier or channel proteins.

  • Osmosis: Diffusion of water across a membrane.

• Active Transport: Requires energy (ATP).

  • Primary: Direct use of ATP (e.g., Na+/K+ pump).

  • Secondary: Uses energy from ion gradients.

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

Summary Table: Types of Membrane Transport

Type	Energy Required?	Mechanism	Examples
Simple Diffusion	No	Movement down concentration gradient	O2, CO2
Facilitated Diffusion	No	Carrier/channel proteins	Glucose, ions
Osmosis	No	Water movement	Water
Primary Active Transport	Yes	Pumps using ATP	Na+/K+ pump
Secondary Active Transport	Yes	Uses ion gradients	Glucose transport
Vesicular Transport	Yes	Endocytosis/exocytosis	Hormone secretion

Example: The Na+/K+ pump maintains cellular ion balance by actively transporting sodium out and potassium into the cell, crucial for nerve impulse transmission.

Additional info: Some details, such as the specific examples of membrane transport and the ATP hydrolysis equation, were inferred to provide academic completeness.