Anatomy and Physiology: Fundamentals, Chemistry, Energy, Histology, and Cell Biology

Comprehensive practice flashcards defining foundational vocabulary in human anatomy, body cavity architecture, chemical principles, cellular respiration, histology, and cellular transport mechanisms.

Anatomy

The study of internal and external body structures and the physical relationships among body parts.

Physiology

The study of how living organisms perform their vital functions, based on the principle that form follows function.

Cytology

The microscopic study of individual cells and their internal structures.

Histology

The microscopic study of tissues and their architectural arrangements.

Anatomical Position

The standard reference posture for the human body: standing upright, upper limbs at the sides, palms facing forward (anteriorly), and feet parallel and flat on the floor.

Visceral Serosa

The inner layer of a serous membrane that directly adheres to and covers the external surface of organs within ventral body cavities.

Parietal Serosa

The outer layer of a serous membrane that lines the inner surface of the body wall or chamber walls.

Mediastinum

The median tissue mass of the thoracic cavity situated between the pleural cavities that encloses the heart, thymus, esophagus, trachea, major blood vessels, and pericardium.

Negative Feedback

The primary homeostatic regulatory mechanism that counteracts or opposes an initial stimulus to restore physiological variables back to within their optimal set-point range.

Positive Feedback

A homeostatic control mechanism in which an initial stimulus triggers a response that amplifies and accelerates the change in the same direction until a climactic event is reached.

Mass Number

The total number of protons plus neutrons located in the nucleus of an atom, used to designate specific isotopes.

Isotopes

Atoms of the same chemical element possessing identical numbers of protons but differing numbers of neutrons, sharing identical chemical properties while differing in mass.

Biological Half-Life

The duration of time required for the body to eliminate half of an introduced radioactive material through normal physiological processes.

Ionic Bond

A chemical bond formed by the electrostatic attraction between a positively charged cation and a negatively charged anion following electron transfer.

Covalent Bond

A chemical bond produced when two atoms fill their outermost electron valence shells by sharing single, double, or triple pairs of electrons.

Amphipathic Molecule

A large chemical molecule possessing distinct polar (hydrophilic) and nonpolar (hydrophobic) regions, such as a membrane phospholipid.

Specific Heat

The amount of thermal energy required to increase the temperature of $1\,\text{gram}$ of a substance by $1\,^\circ\text{C}$; exceptionally high in water due to the energy needed to break hydrogen bonds.

Heat of Vaporization

The quantity of heat required for $1\,\text{gram}$ of a substance to transition from liquid phase to gas phase, enabling thermoregulatory cooling via sweat evaporation.

Electrolyte

An inorganic substance, such as a salt, acid, or base, that dissociates or ionizes in water to release ions capable of conducting an electrical current.

Buffer

A chemical substance or solution, typically consisting of a weak acid and its conjugate base, that stabilizes pH by binding or releasing hydrogen ions ($\text{H}^+$) upon the addition of acids or bases.

Saturated Fatty Acid

A hydrocarbon chain where each carbon atom in the tail is bonded to the maximum possible number of hydrogen atoms through single covalent bonds.

Triglyceride

The most common lipid in the body, composed of a glycerol molecule esterified to three fatty acid chains, functioning in energy storage, thermal insulation, and physical cushioning.

Chemical Energy

A form of potential energy stored in the chemical bonds between atoms that is released when those bonds are broken during chemical reactions.

First Law of Thermodynamics

The physical law stating that energy can neither be created nor destroyed, but can only be converted from one form to another.

Second Law of Thermodynamics

The physical law stating that with each conversion of energy from one form to another, an amount of energy is converted into heat.

Catabolism

The collective decomposition reactions within an organism that break down complex molecules into smaller fragments, typically releasing kinetic and thermal energy.

Anabolism

The collective synthesis reactions within an organism that form chemical bonds to join smaller molecules into complex structures, requiring an energy input.

Activation Energy

The minimum quantity of energy required to initiate a chemical reaction, which biological catalysts (enzymes) lower to accelerate reaction rates.

Denaturation

A permanent structural alteration and conformational unfolding of an enzyme or protein caused by hostile pH or elevated temperature, resulting in total loss of catalytic function.

Cofactor

A nonprotein helper ion or organic molecule (coenzyme) that must bind to an enzyme before substrates can be catalyzed.

Glycolysis

An anaerobic metabolic pathway occurring in the cytosol that splits one molecule of glucose into two molecules of pyruvate, yielding a net $2\,\text{ATP}$ and $2\,\text{NADH}$.

Citric Acid Cycle

An aerobic enzymatic pathway occurring in the mitochondrial matrix that catabolizes pyruvic acid derivatives to produce $2\,\text{ATP}$, $6\,\text{NADH}$, and $2\,\text{FADH}_2$ per glucose molecule.

Glycogenesis

The slow enzymatic formation of glycogen from glucose monomers, requiring the high-energy nucleoside uridine triphosphate ($\text{UTP}$).

Glycogenolysis

The rapid breakdown of stored glycogen into glucose subunits occurring through a single enzymatic step.

Apical Surface

The superior, exposed surface of epithelial cells oriented toward an internal lumen or the external environment, often bearing microvilli or motile cilia.

Basement Membrane

A thin, acellular anchoring layer located between the basal surface of an epithelium and underlying connective tissue, composed of a basal lamina and a reticular lamina.

Gap Junction

An intercellular junction constructed from transmembrane protein complexes called connexons, forming narrow aqueous channels that allow direct passage of ions and small signaling molecules between adjacent cells.

Desmosome

A mechanical anchoring junction consisting of a protein plaque and cell adhesion molecules (CAMs) interlocked with cytoplasmic intermediate filaments, resisting mechanical shearing forces.

Keratinized Stratified Squamous Epithelium

A multilayered protective epithelium whose basal cells divide while apical cells become flattened, lose their nuclei and organelles, fill with tough keratin protein, and die (found in the epidermis of skin).

Transitional Epithelium

A specialized stratified epithelium lining the urinary tract that features dome-shaped or binucleated apical cells capable of stretching and flattening reversibly as fluid volume expands.

Goblet Cell

A solitary, unicellular exocrine gland embedded within columnar or pseudostratified epithelia that synthesizes and secretes the mucin glycoprotein.

Merocrine Gland

An exocrine gland whose secretions are packaged into intracellular vesicles and released at the apical cell surface via exocytosis without injury to the secretory cell (e.g., salivary glands).

Apocrine Gland

An exocrine gland that releases its secretory product by pinching off the apical portion of the cytoplasm, followed by cell regrowth and repair (e.g., mammary glands).

Holocrine Gland

An exocrine gland whose cells accumulate lipid-rich secretions, burst, and completely disintegrate to form the glandular product, replaced continuously by basal stem cell division (e.g., sebaceous glands).

Mesenchyme

The primordial embryonic connective tissue consisting of star-shaped mesenchymal cells immersed in a fluid ground substance that gives rise to all other mature connective tissues.

Dense Regular Connective Tissue

A dense connective tissue containing parallel, densely packed collagen fiber bundles with few blood vessels and flattened fibroblasts, providing high tensile strength along a single plane (e.g., tendons and ligaments).

Chondrocyte

A mature cartilage cell that resides within a small enclosed space in the extracellular matrix termed a lacuna.

Intercalated Disc

A specialized junctional complex linking adjacent branching cardiac muscle fibers that mechanically locks cells together and facilitates electrical impulse transmission across the myocardium.

Neuroglia

The non-conducting support cells of nervous tissue that physically stabilize, repair, protect, phagocytize debris, and nourish neurons.

Metaplasia

A reversible phenotypic transformation of one mature epithelial tissue type into another in response to chronic environmental irritation or injury (e.g., ciliated columnar transforming into stratified squamous in smokers).

Hypertrophy

An increase in the total mass and volume of a tissue caused by an enlargement in the size of individual existing cells rather than an increase in cell number.

Hyperplasia

An increase in the overall size of a tissue or organ resulting from an increase in the total number of cells through accelerated mitotic cell division.

Gangrene

The clinical necrosis and decay of soft body tissues resulting from severe arterial ischemia and compromised blood supply, frequently affecting extremities or internal organs.

Centrosome

A nonmembranous organelle located near the nucleus containing a pair of perpendicular centrioles (each organized in a $9+0$ microtubule triplet array) that orchestrates spindle fiber assembly during cell division.

Peroxisome

A small membranous vesicle filled with degradative oxidase enzymes that catabolizes fatty acids and neutralizes toxic metabolic byproducts such as free radicals.

Lysosome

A spherical, membrane-bound organelle containing digestive enzymes that catabolizes damaged organelles, internalized foreign debris, or whole bacterial pathogens.

Carrier-Mediated Diffusion

A passive facilitated transport process in which specific polar solutes (such as glucose) bind to integral membrane carrier proteins, triggering conformational shifts that move the molecule down its concentration gradient without energy consumption.

Osmotic Pressure

The physical force generated by the net movement of water across a semipermeable membrane driven by differences in solute concentrations.

Crenation

The cellular shriveling and scalloping that occurs when an animal cell is immersed in a hypertonic solution as water exits down its concentration gradient via osmosis.

Sodium-Potassium Exchange Pump

A primary active transport carrier mechanism that hydrolyzes $1\,\text{ATP}$ to pump $3\,\text{Na}^+$ ions out of the cell while transporting $2\,\text{K}^+$ ions in, maintaining the resting membrane potential.

Phagocytosis

A form of bulk endocytosis ('cell eating') wherein a cell extends cytoplasmic pseudopodia around large extracellular particulate matter or microorganisms to enclose them within an internal phagosome.

Pinocytosis

A non-specific vesicular endocytic process ('cell drinking') where small invaginations of the plasma membrane engulf droplets of extracellular fluid containing dissolved nutrients.

Transcription

The nuclear stage of protein synthesis in which RNA polymerase reads a specific gene sequence on DNA to transcribe a complementary strand of messenger RNA ($\text{mRNA}$).

Translation

The ribosomal stage of protein synthesis occurring in the cytosol where codon triplets on an $\text{mRNA}$ strand are decoded into a linear sequence of amino acids.

Cleavage Furrow

A shallow contractile indentation that encircles the equator of a dividing animal cell during telophase and cytokinesis, eventually pinching the cytoplasm into two daughter cells.