Anatomy & Physiology: Essential Concepts and Terminology

Introduction to Anatomy & Physiology

This study guide covers foundational concepts, terminology, and systems relevant to a college-level Anatomy & Physiology course. It is organized by major topics and subtopics, providing definitions, examples, and key facts to support exam preparation.

Basic Characteristics of Life

Essential Life Functions

• Cell: The smallest unit capable of carrying out the functions of life.

• Metabolism: The sum of all chemical reactions in the body.

• Growth: Increase in size of individual cells or in the number of cells.

• Excretion: Removal of waste products from the body.

• Responsiveness: Sensing and reacting to changes in the environment.

• Movement: Ability of an entire organism or its parts to move.

• Reproduction: Production of new cells within an organism or the production of offspring.

Levels of Structural Organization

• Chemicals → Cells → Tissues → Organs → Organ Systems → Organism

Major Organ Systems

Overview of Organ Systems

• Integumentary System: Skin and accessory organs; protects the body, produces vitamin D, retains water, regulates temperature.

• Skeletal System: Bones and associated cartilages; supports the body, protects organs, produces blood cells, stores calcium.

• Muscular System: Skeletal muscles and connective tissues; produces movement, controls body openings, generates heat.

• Lymphatic System: Lymph nodes, vessels, spleen, tonsils, thymus; returns excess fluid to cardiovascular system, provides immunity.

• Respiratory System: Delivers oxygen to blood, removes carbon dioxide.

• Digestive System: Alimentary canal and accessory organs; digests food, absorbs nutrients, removes waste.

• Nervous System: Brain, spinal cord, nerves; regulates body functions, sensation, movement, higher mental functions.

• Endocrine System: Glands that secrete hormones; regulate functions of other cells and tissues.

• Cardiovascular System: Heart and blood vessels; delivers oxygen and nutrients, removes wastes.

• Urinary System: Kidneys, ureters, bladder, urethra; removes metabolic wastes, regulates fluid, electrolyte, and acid-base balance, stimulates red blood cell production.

• Reproductive System: Sex organs; produces gametes and hormones, allows for offspring production.

Types of Anatomy

• Gross Anatomy: Study of structures visible to the naked eye.

• Microscopic Anatomy: Study of structures only visible with a microscope.

• Histology: Study of tissues.

• Cytology: Study of cells.

Anatomical Terminology

Body Positions and Directions

• Anatomical Position: Body standing upright, feet shoulder-width apart, arms at sides, palms facing forward.

• Anterior (Ventral): Toward the front.

• Posterior (Dorsal): Toward the back.

• Superior (Cranial): Toward the head.

• Inferior (Caudal): Toward the tail.

• Proximal: Closer to the point of origin (usually the trunk).

• Distal: Farther from the point of origin.

• Medial: Toward the midline.

• Lateral: Away from the midline.

• Superficial: Closer to the surface.

• Deep: Farther from the surface or more internal.

Body Planes

• Sagittal Plane: Divides body into right and left portions.

• Midsagittal Plane: Divides body into equal right and left halves.

• Parasagittal Plane: Divides body into unequal right and left portions.

• Frontal (Coronal) Plane: Divides body into anterior and posterior portions.

• Transverse (Horizontal) Plane: Divides body into superior and inferior portions.

Body Cavities

• Cavity: Any fluid-filled space within the body.

• Dorsal Body Cavity: Includes cranial and vertebral (spinal) cavities.

• Cranial Cavity: Houses the brain.

• Spinal Cavity: Houses the spinal cord.

• Ventral Body Cavity: Includes thoracic and abdominopelvic cavities.

• Thoracic Cavity: Includes pleural, mediastinum, and pericardial cavities.

• Pleural Cavities: Surround each lung.

• Mediastinum: Central thoracic cavity between the lungs.

• Pericardial Cavity: Potential space between pericardial membranes, surrounds the heart.

• Abdominopelvic Quadrants: Used to localize problems; include upper right, upper left, lower right, lower left.

Serous Membranes

• Serous Membrane: Thin sheets of tissue that envelope organs and produce serous fluid.

• Visceral Layer: In contact with the underlying organ.

• Parietal Layer: In contact with the body wall.

Homeostasis and Feedback Mechanisms

• Homeostasis: Maintenance of a stable internal environment.

• Homeostatic Imbalance: Disturbances in homeostasis that can lead to disease or death.

• Negative Feedback Loop: Response in which a change in a variable causes actions that return the variable to its original state. Example: Regulation of body temperature.

• Positive Feedback Loop: Response in which the effector's activity increases, amplifying the response. Example: Childbirth contractions.

Basic Chemistry for Anatomy & Physiology

Structure of Matter

• Matter: Anything that has mass and takes up space.

• Chemistry: Study of matter and its interactions.

• Atom: Smallest unit of matter retaining its properties.

• Proton: Positively charged subatomic particle in the nucleus.

• Neutron: Neutrally charged subatomic particle in the nucleus.

• Electron: Negatively charged subatomic particle in electron shells.

• Electron Shells: Energy levels where electrons reside. First shell holds 2, second holds 8, third holds up to 18 electrons.

• Atomic Number: Number of protons in an atom.

• Mass Number: Number of protons plus neutrons.

• Isotope: Element with the same number of protons but different number of neutrons.

Types of Mixtures

• Suspension: Large, unevenly distributed particles that settle out.

• Colloid: Small, evenly distributed particles that do not settle out.

• Solution: Extremely small, evenly distributed particles that do not settle out.

Chemical Bonds and Reactions

• Molecule: Formed by chemical bonding between two or more atoms.

• Compound: Formed when atoms of different elements bond.

• Inert Element: Unreactive due to a full outer shell of electrons.

• Ionic Bond: Electrons are transferred from a metal to a nonmetal atom.

• Ion: Charged particle (cation = positive, anion = negative).

• Covalent Bond: Sharing of electrons between atoms.

• Nonpolar Covalent Bond: Equal sharing of electrons.

• Polar Covalent Bond: Unequal sharing of electrons.

• Hydrogen Bond: Weak attraction between partial positive and negative ends of dipoles; responsible for water's surface tension.

• Chemical Reaction: Process where chemical bonds are formed, broken, or rearranged.

• Reactant: Substance that enters a reaction.

• Product: Substance produced by a reaction.

Energy in Biological Systems

• Energy: Capacity to do work.

• Potential Energy: Stored energy.

• Kinetic Energy: Energy of motion.

• Endergonic Reaction: Requires input of energy.

• Exergonic Reaction: Releases excess energy.

Types of Chemical Reactions

• Anabolic Reaction: Build up molecules (synthesis).

• Catabolic Reaction: Break down molecules (decomposition).

• Oxidation-Reduction (Redox) Reaction: Transfer of electrons; oxidation = loss, reduction = gain.

• Enzyme: Biological catalyst that lowers activation energy and is not consumed in the reaction.

Inorganic and Organic Compounds

• Inorganic Compounds: Generally do not contain carbon-hydrogen bonds (e.g., water, acids, bases, salts).

• Organic Compounds: Contain carbon bonded to hydrogen (e.g., carbohydrates, lipids, proteins, nucleic acids).

Water and pH

• Water: Makes up 60-80% of body mass; high heat capacity, evaporative cooling, cushioning, solvent.

• Hydrophilic: Water-loving.

• Hydrophobic: Water-fearing.

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

• Base: Accepts H+ or releases hydroxide ions (OH-); pH above 7.

• pH Scale: Measures hydrogen ion concentration; scale 0-14, 7 is neutral. Blood pH: 7.35-7.45.

• Buffer: Resists changes in pH.

Macromolecules

• Monomer: Single subunit that can be combined to form polymers.

• Polymer: Large molecule made of monomers.

• Dehydration Synthesis: Builds polymers by removing water.

• Hydrolysis: Breaks down polymers by adding water.

• Carbohydrates: Organic molecules composed of C, H, O in a 1:2:1 ratio.

• Monosaccharide: Simple sugar monomer.

• Polysaccharide: Carbohydrate polymer of many monosaccharides.

• Lipids: Nonpolar molecules (fats, oils, steroids).

• Saturated Fatty Acid: No double bonds between carbons.

• Monounsaturated Fatty Acid: One double bond.

• Polyunsaturated Fatty Acid: Two or more double bonds.

• Triglyceride: Main fat storage molecule.

• Phospholipid: Two fatty acids and a phosphate group; major component of cell membranes.

• Steroid: Four-ring hydrocarbon structure (e.g., cholesterol).

• Amino Acid: Monomer of proteins.

• Protein Structure: Primary (amino acid sequence), secondary (alpha helix/beta sheet), tertiary (3D folding), quaternary (multiple polypeptides).

• Nucleotide: Monomer of nucleic acids.

• ATP (Adenosine Triphosphate): Main energy currency of the cell.

• DNA: Double helix, deoxyribose sugar, bases A, T, G, C.

• RNA: Single strand, ribose sugar, bases A, U, G, C.

Cell Structure and Function

• Cytosol: Fluid inside the cell containing water and solutes.

• Organelle: Specialized structure within a cell performing specific functions.

• Phospholipid Bilayer: Double layer forming the cell membrane; hydrophilic heads face outward, hydrophobic tails inward.

• Active Transport: Requires energy (ATP) to move substances against their gradient.

• Passive Transport: Does not require energy; includes simple diffusion, facilitated diffusion, osmosis.

• Osmosis: Diffusion of water across a membrane.

• Isotonic Solution: Same solute concentration as the cell; no net water movement.

• Hypertonic Solution: Higher solute concentration than the cell; water leaves the cell.

• Hypotonic Solution: Lower solute concentration than the cell; water enters the cell.

• Endocytosis: Cell takes in substances via vesicles.

• Exocytosis: Cell expels substances via vesicles.

• Mitochondria: Double-membraned organelle; site of ATP production.

• Ribosome: Site of protein synthesis.

• Rough Endoplasmic Reticulum (RER): Membranes with ribosomes; protein synthesis and modification.

• Smooth Endoplasmic Reticulum (SER): No ribosomes; lipid synthesis, detoxification.

• Golgi Apparatus: Modifies, sorts, and packages proteins and lipids.

• Lysosome: Contains digestive enzymes.

• Centrosome: Contains centrioles; important in cell division.

• Microvilli: Increase surface area for absorption.

• Cilia: Move substances across cell surface.

• Flagella: Used for locomotion (e.g., sperm cell).

• Nucleus: Contains DNA; control center of the cell.

• Chromatin: DNA and associated proteins in a loose form.

• Chromosome: Condensed form of DNA during cell division.

• Nucleolus: Site of ribosome production.

Protein Synthesis

• Transcription: DNA is copied into mRNA.

• Translation: mRNA is decoded to build a protein.

Cell Cycle and Division

• Interphase: G1 (growth), S (DNA replication), G2 (preparation for division).

• Mitosis: Division of the nucleus (prophase, metaphase, anaphase, telophase).

• Cytokinesis: Division of the cytoplasm.

• Apoptosis: Programmed cell death.

• Mutation: Change in DNA sequence.

• Cancer: Uncontrolled cell division.

• Metastasis: Spread of cancer cells to other parts of the body.

Tissues and Membranes

Types of Tissues

• Epithelial Tissue: Covers and lines body surfaces and cavities; tightly packed cells, avascular, regenerative.

• Connective Tissue: Supports, protects, and binds other tissues; includes loose, dense, reticular, adipose, cartilage, bone, blood.

• Muscle Tissue: Contracts to produce movement; includes skeletal (voluntary), cardiac (involuntary, heart), smooth (involuntary, organs).

• Nervous Tissue: Generates and transmits electrical signals; includes neurons and neuroglia.

Extracellular Matrix (ECM)

• Non-cellular material surrounding cells; provides structural and biochemical support.

Epithelial Tissue Classification

• Simple Epithelium: One cell layer thick.

• Stratified Epithelium: Multiple cell layers.

• Squamous: Flattened cells.

• Cuboidal: Cube-shaped cells.

• Columnar: Tall, elongated cells.

• Goblet Cell: Specialized cell that secretes mucus.

• Keratinized Stratified Squamous Epithelium: Found in the outer layer of skin.

• Simple Columnar Epithelium: Lines digestive tract.

• Pseudostratified Ciliated Columnar Epithelium: Lines respiratory tract.

• Transitional Epithelium: Lines urinary organs; cells change shape when stretched.

Glandular Epithelium

• Endocrine Glands: Secrete hormones directly into the bloodstream.

• Exocrine Glands: Secrete products into ducts.

• Merocrine Secretion: Products released by exocytosis.

• Holocrine Secretion: Products released when cell ruptures and dies.

Connective Tissue Types

• Loose Connective Tissue: Widely distributed, supports and binds tissues.

• Dense Connective Tissue: Provides strength and support.

• Reticular Tissue: Forms supportive framework in lymphoid organs.

• Adipose Tissue: Stores fat, insulates, cushions, and protects.

• Cartilage: Three types: hyaline, fibrocartilage, elastic.

• Bone Tissue: Provides protection and support; matrix contains calcium phosphate.

• Blood: Fluid connective tissue; transports substances.

Muscle and Nervous Tissue

• Skeletal Muscle: Voluntary, attached to bones, movement.

• Cardiac Muscle: Involuntary, found only in the heart.

• Smooth Muscle: Involuntary, found in walls of hollow organs.

• Neurons: Transmit electrical signals.

• Neuroglia: Support and protect neurons.

Membranes

• Serous Membrane: Lines body cavities not open to the outside; produces serous fluid.

• Synovial Membrane: Lines joint cavities; produces synovial fluid.

• Mucous Membrane: Lines body passages open to the outside.

• Cutaneous Membrane: The skin.

Cell Junctions

• Gap Junction: Protein channels allowing communication between cells.

• Tight Junction: Hold cells closely together, preventing passage of substances.

Tissue Repair

• Tissue Repair: Process of replacing dead or damaged cells with new cells or tissue.

• Stem Cell: Immature cell capable of replacing worn-out cells.

Summary Table: Body Planes and Directions

Term	Definition
Anterior (Ventral)	Toward the front
Posterior (Dorsal)	Toward the back
Superior (Cranial)	Toward the head
Inferior (Caudal)	Toward the tail
Medial	Toward the midline
Lateral	Away from the midline
Proximal	Closer to the point of origin
Distal	Farther from the point of origin
Superficial	Closer to the surface
Deep	Farther from the surface

Key Equations and Formulas

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

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

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