Foundations of Chemistry and Cell Biology in Anatomy & Physiology

Chemistry in Anatomy & Physiology

Basic Chemistry Terminology

Chemistry provides the foundational principles for understanding biological processes in Anatomy & Physiology. Key terminology is essential for describing matter and its interactions.

• 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 unit of an element, composed of protons, neutrons, and electrons.

• Proton: Positively charged particle in the nucleus of an atom.

• 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.

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

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

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

Chemical Bonds

Chemical bonds are forces that hold atoms together in molecules and compounds.

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

• Covalent Bonds: Formed by the sharing of electrons between atoms.

• Hydrogen Bonds: Weak attractions between a hydrogen atom and an electronegative atom (e.g., oxygen or nitrogen).

Chemical Reactions

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

• Types of Reactions: Synthesis, decomposition, exchange.

• Energy Release: Some reactions release energy (exergonic), while others absorb energy (endergonic).

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

Properties of Inorganic Compounds

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

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

• Acids: Substances that release hydrogen ions ($H^+$) in solution. Example: Hydrochloric acid ($HCl$).

• Bases: Substances that release hydroxide ions ($OH^-$) or accept hydrogen ions. Example: Sodium hydroxide ($NaOH$).

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

• pH and Acid/Base Concentration: pH measures hydrogen ion concentration. $pH = -\log[H^+]$ Acidic: pH < 7, Neutral: pH = 7, Basic: pH > 7

Properties of Organic Compounds

Monomers, Polymers, and Synthesis

Organic compounds are built from monomers joined to form polymers through dehydration synthesis and broken down by hydrolysis.

• Monomer: Small molecule that can join with others to form a polymer.

• Polymer: Large molecule made of repeating monomer units.

• Dehydration Synthesis: Reaction that joins monomers by removing water.

• Hydrolysis: Reaction that breaks polymers into monomers by adding water.

Carbohydrates

Carbohydrates are energy sources and structural molecules.

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

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

• Polysaccharides: Long chains of monosaccharides (e.g., starch, glycogen).

• Formation/Breakdown: Formed by dehydration synthesis, broken down by hydrolysis.

• 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: No double bonds; solid at room temperature.

  • Unsaturated: One or more double bonds; liquid at room temperature.

  • Function: Long-term energy storage and insulation.

• Phospholipids: Major component of cell membranes; have polar (hydrophilic) heads and nonpolar (hydrophobic) tails.

• Steroids: Four-ring structure; includes cholesterol, vitamin D, and hormones.

Proteins (Polypeptides)

Proteins are polymers of amino acids with diverse functions including structure, transport, and catalysis.

• General Characteristics: Composed of amino acids linked by peptide bonds.

• Levels of Organization:

  • Primary: Sequence of amino acids.

  • Secondary: Alpha helices and beta sheets formed by hydrogen bonding.

  • Tertiary: 3D folding due to interactions among R groups.

  • Quaternary: Association of multiple polypeptide chains.

• Categories:

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

  • Globular: Functional proteins (e.g., enzymes, hemoglobin).

• Enzymes: Biological catalysts that speed up reactions by lowering activation energy.

  • Importance: Essential for metabolism.

  • Three Steps of Enzyme Action: Substrate binding, transition state facilitation, product release.

Nucleic Acids

Nucleic acids store and transmit genetic information.

• DNA: Deoxyribonucleic acid; stores genetic instructions.

• RNA: Ribonucleic acid; involved in protein synthesis.

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

• ATP Function: Provides energy for cellular processes.

Cytology: The Study of Cells

Plasma Membrane

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

• General Functions: Protects cell contents, regulates entry/exit of substances, facilitates communication.

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

Proteins in the Plasma Membrane

Membrane proteins serve various functions including transport, signaling, and structural support.

• Integral Proteins: Span the membrane; involved in transport and signaling.

• Peripheral Proteins: Attached to the membrane surface; involved in structural support and signaling.

Cell Junctions

Cell junctions connect cells and facilitate communication and structural integrity.

• Tight Junctions: Prevent leakage between cells.

• Desmosomes: Anchor cells together, providing mechanical strength.

• Gap Junctions: Allow passage of ions and small molecules for cell-to-cell communication.

Membrane Transport

Transport across the plasma membrane is essential for nutrient uptake, waste removal, and signaling.

• Passive Transport: Movement of substances without energy input.

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

  • Facilitated Diffusion: Movement via carrier or channel proteins.

  • Osmosis: Diffusion of water across a semipermeable membrane.

• Active Transport: Movement of substances against concentration gradient, requiring energy (ATP).

  • Primary Active Transport: Direct use of ATP (e.g., sodium-potassium pump).

  • Secondary Active Transport: Uses energy from ion gradients.

  • Vesicular Transport: Movement of large particles via endocytosis (into cell) and exocytosis (out of cell).

Type of Membrane Transport	Energy Required?	Example
Simple Diffusion	No	Oxygen entering cells
Facilitated Diffusion	No	Glucose transport via carrier proteins
Osmosis	No	Water movement in kidneys
Primary Active Transport	Yes (ATP)	Sodium-potassium pump
Secondary Active Transport	Yes (ion gradient)	Glucose-sodium co-transport
Vesicular Transport	Yes (ATP)	Endocytosis, exocytosis

Additional info: Academic context and definitions have been expanded for clarity and completeness. Table entries inferred for illustrative purposes.