Anatomy & Physiology I: Study Guide for Test 1 (Chapters 1–3)

Introduction to Anatomy & Physiology

Definitions and Relationship

Anatomy is the study of the structure of body parts, while physiology is the study of the function of those parts. The two fields are closely related because the structure of a body part often determines its function.

• Anatomy: Focuses on the physical form and organization of body structures.

• Physiology: Explores how those structures work and interact.

• Relationship: "Form follows function"—the way something is built enables what it does.

Scientific Terminology

• Hypothesis: A testable, educated guess or prediction about how things work.

• Fact: An objective, confirmed observation.

• Law: A descriptive generalization about how some aspect of the natural world behaves under stated circumstances.

• Theory: A well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment.

Levels of Human Structure

The human body is organized in a hierarchy from the most complex to the simplest:

• Organism

• Organ System

• Organ

• Tissue

• Cell

• Organelle

• Molecule

• Atom

Characteristics of Living Things

• Composed of cells

• Organized structure

• Responsiveness to environment

• Regulation (homeostasis)

• Growth and development

• Reproduction

• Metabolism (all chemical reactions in the body)

Homeostasis

Homeostasis is the maintenance of a stable internal environment. It is central to physiology because it allows organisms to function optimally despite external changes.

• Failure to maintain homeostasis leads to illness, disease, disorder, or death.

• Maintained by automatic self-regulating feedback loops involving:

  • Receptor: Detects changes

  • Control Center: Processes information and determines response

  • Effector: Carries out the response

Negative Feedback

• Reduces or negates the original stimulus.

• Example: Body temperature regulation—if too cold, mechanisms increase temperature.

• Essential for maintaining homeostasis.

Positive Feedback

• Enhances or amplifies the original stimulus.

• Example (beneficial): Labor contractions during childbirth.

• Example (harmful): Excessive blood clotting or fever spiraling out of control.

Anatomical Position, Directional Terms, and Planes

• Anatomical Position: Standing upright, facing forward, arms at sides, palms forward.

• Directional Terms:

  • Caudal (toward tail/bottom) – Cephalic (toward head)

  • Prone (lying face down) – Supine (lying on back)

  • Anterior (front), Posterior (back), Dorsal (back), Ventral (front), Superior (above), Inferior (below)

  • Proximal (closer to trunk), Distal (farther from trunk), Medial (toward midline), Lateral (away from midline)

• Planes:

  • Frontal (coronal): Divides body into front and back

  • Sagittal: Divides body into left and right

  • Transverse: Divides body into top and bottom

  • Oblique: Divides body at an angle

Chemical Level of Organization

Properties of Water

Water is essential to life due to its unique properties:

• Cohesion: Water molecules stick together.

• Adhesion: Water molecules stick to other substances.

• High heat of vaporization: Requires a lot of energy to change from liquid to gas.

• Hydrogen bonds: Weak attractions between water molecules that give water its unique properties.

Atoms, Elements, and Subatomic Particles

• Atom: Smallest unit of matter.

• Element: Pure substance made of only one kind of atom.

• Proton: Positive charge, found in nucleus.

• Neutron: No charge, found in nucleus.

• Electron: Negative charge, orbits nucleus.

• Atomic Number: Number of protons.

• Mass Number: Number of protons + neutrons.

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

Chemical Bonds

• Ionic Bond: Electrons are transferred from one atom to another, creating ions.

• Covalent Bond: Electrons are shared between atoms.

• Valence Electrons: Electrons in the outermost shell, involved in bond formation.

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

• Non-polar Molecule: Equal sharing of electrons, no charge separation.

Acids, Bases, and pH

• Acid: Releases H+ ions in solution; pH < 7.

• Base: Releases OH- ions in solution; pH > 7.

• pH Scale: Measures hydrogen ion concentration; ranges from 0 (acidic) to 14 (basic).

• Buffer: Stabilizes pH by removing or adding H+ as needed.

Macromolecules

• Carbohydrates: CHO, 1:2:1 ratio, main energy source. Monomer: Monosaccharide (e.g., glucose).

• Lipids: CH (few O), energy storage, insulation. Monomer: Fatty acids, glycerol.

• Proteins: CHON, structure, enzymes, transport. Monomer: Amino acids.

• Nucleic Acids: CHONP, genetic information. Monomer: Nucleotide (DNA, RNA).

Why are they organic? They contain both carbon and hydrogen.

Formation and Breakdown of Macromolecules

• Dehydration Synthesis (Condensation): Joins monomers by removing water.

• Hydrolysis (Decomposition): Breaks polymers into monomers by adding water.

Functional Groups

• Specific groups of atoms within molecules that have characteristic properties.

• Example: Amino group (-NH2) in amino acids.

• R Group: Variable side chain in amino acids, determines properties.

Protein Structure

• Primary: Sequence of amino acids.

• Secondary: Alpha helix or beta pleated sheet (hydrogen bonding).

• Tertiary: 3D folding of polypeptide.

• Quaternary: Multiple polypeptides combine.

Enzymes

• Biological catalysts that lower activation energy of reactions.

• Structure (shape) is critical to function; denaturation (loss of shape) leads to loss of function.

Hydrophobic vs Hydrophilic

• Hydrophobic: Repels water (nonpolar molecules).

• Hydrophilic: Attracts water (polar molecules).

• Impacts how molecules interact and organize in cells (e.g., cell membrane structure).

Cellular Level of Organization

Cell Theory

• All living things are composed of cells.

• Cells are the basic unit of structure and function in living things.

• All cells come from pre-existing cells.

Cell Membrane Structure

• Composed of a phospholipid bilayer with embedded proteins, cholesterol, and carbohydrates.

• Functions as a selective barrier, controlling entry and exit of substances.

Cell Surface Structures

• Microvilli: Increase surface area for absorption.

• Cilia: Move fluids, mucus, and particles; sensory functions.

• Flagella: Propel cells (e.g., sperm).

Osmolarity and Tonicity

• Osmolarity: Total concentration of solute particles in a solution.

• Tonicity: Effect of a solution on cell volume (isotonic, hypotonic, hypertonic).

• Isotonic: No net water movement; cell volume unchanged.

• Hypotonic: Water enters cell; cell swells or bursts (hemolysis).

• Hypertonic: Water leaves cell; cell shrinks (crenation).

Membrane Transport

• Passive Transport: No ATP required; moves substances from high to low concentration.

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

  • Facilitated Diffusion: Uses protein channels to move substances across membrane.

  • Osmosis: Diffusion of water across a membrane.

• Active Transport: Requires ATP; moves substances from low to high concentration.

  • Ion Pumps: e.g., Na+/K+ pump, crucial for nerve and muscle function.

  • Secondary Active Transport: Uses energy from one substance moving down its gradient to move another up its gradient (e.g., glucose with Na+).

  • Endocytosis/Exocytosis: Bulk transport into/out of cell.

Cell Organelles

• Cytoplasm: Jelly-like fluid inside the cell, contains organelles.

• Membranous Organelles: Surrounded by membranes (e.g., nucleus, mitochondria, endoplasmic reticulum).

• Non-membranous Organelles: Not surrounded by membranes (e.g., ribosomes, cytoskeleton).

Protein Synthesis

• Transcription: Occurs in nucleus; DNA is copied into mRNA.

• Translation: Occurs in cytoplasm; ribosomes use mRNA to assemble amino acids into proteins. tRNA delivers amino acids to ribosome.

• If ribosome is attached to rough ER, polypeptide enters ER for processing.

Cell Cycle

• Two main phases: Interphase (cell growth, DNA replication) and Mitotic Phase (cell division).

• Mitosis: Division of somatic cells; produces two identical diploid daughter cells.

• Meiosis: Division of sex cells; produces four haploid daughter cells with genetic variation.

Cancer Terminology

• Benign: Non-cancerous, does not spread.

• Malignant: Cancerous, can invade and destroy tissue.

• Metastasized: Cancer has spread to other parts of the body.

Chromatin, Chromatids, and Centromeres

• Chromatin: DNA, RNA, and proteins in the nucleus.

• Sister Chromatids: Identical copies of a chromosome, joined at the centromere.

• Centromere: Region where sister chromatids are joined; attachment site for spindle fibers.

Stages of Mitosis

• Prophase: Chromosomes condense, spindle forms.

• Metaphase: Chromosomes align at cell equator.

• Anaphase: Sister chromatids separate and move to opposite poles.

• Telophase: Nuclear envelope reforms, chromosomes uncoil.

• Followed by cytokinesis (division of cytoplasm).

DNA Replication

• Occurs during S phase of interphase.

• Ensures each daughter cell receives an identical set of chromosomes after mitosis.

Summary Table: Macromolecules

Macromolecule	Elements	Monomer	Main Functions	Example
Carbohydrates	C, H, O (1:2:1)	Monosaccharide	Energy source, structure	Glucose, starch
Lipids	C, H (few O)	Fatty acid, glycerol	Energy storage, insulation	Triglyceride, phospholipid
Proteins	C, H, O, N	Amino acid	Structure, enzymes, transport	Hemoglobin, enzymes
Nucleic Acids	C, H, O, N, P	Nucleotide	Genetic information	DNA, RNA

Key Equations

• Mass Number: $\text{Mass Number} = \text{Number of Protons} + \text{Number of Neutrons}$

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

Additional info: Some explanations and examples have been expanded for clarity and completeness, following standard academic sources for introductory anatomy and physiology.