Essentials of Human Anatomy & Physiology - Chapter 3: Cells and Tissues Vocabulary

Vocabulary practice flashcards covering cell anatomy, cell transport mechanisms, cell division stages, and primary body tissue classifications from Chapter 3 of Essentials of Human Anatomy & Physiology.

Cell Theory

The foundational biological principles stating that a cell is the basic structural and functional unit of living organisms, that organismal activity depends on collective cellular activities, that cellular function is dictated by structure (principle of complementarity), and that continuity of life has a cellular basis.

Principle of Complementarity

The anatomical principle stating that the biochemical activities of cells are dictated by their specific structure (anatomy), which determines their function (physiology).

Plasma Membrane

A transparent, selectively permeable phospholipid barrier containing scattered cholesterol and proteins that encloses cellular contents and separates them from the surrounding environment.

Fluid Mosaic Model

A model of cell membrane structure consisting of two phospholipid layers arranged tail-to-tail with cholesterol, proteins, and glycoproteins scattered throughout.

Hydrophilic

The 'water-loving' property of charged polar phospholipid heads that orient toward the inner and outer watery surfaces of the plasma membrane.

Hydrophobic

The 'water-fearing' property of nonpolar fatty acid tails that line the interior center of the plasma membrane, rendering it impermeable to most water-soluble molecules.

Glycocalyx

The fuzzy, sticky, sugar-rich area on the cell's exterior surface formed by glycoproteins and glycolipids.

Tight Junctions

Impermeable cell junctions where adjacent plasma membranes fuse zipper-like to create leakproof sheets that prevent substances from passing through intercellular space.

Desmosomes

Anchoring cell junctions consisting of buttonlike thickenings of adjacent plasma membranes that prevent cells subjected to mechanical stress from being pulled apart.

Gap Junctions

Communicating cell junctions composed of hollow protein cylinders called connexons that span adjacent cell membranes, allowing direct chemical transport between cells.

Nucleus

The central control center of the cell that contains genetic material (DNA) required for protein synthesis and cellular reproduction.

Nuclear Envelope

A double-membrane barrier pierced by large nuclear pores that bounds the nucleus and encloses the fluid nucleoplasm.

Nucleolus

A dark-staining, non-membrane-bounded body within the nucleus where ribosome subunits are assembled.

Chromatin

Granular, threadlike material scattered through the nucleus during interphase, composed of DNA coiled around histone proteins.

Cytosol

The semitransparent fluid portion of cytoplasm that suspends organelles, nutrients, and electrolytes.

Inclusions

Non-functioning chemical substances suspended in cytosol, such as stored lipid droplets, glycogen granules, pigment granules, or crystals.

Mitochondria

Double-membrane organelles with folded inner cristae that produce ATP through aerobic cellular respiration ('powerhouses of the cell').

Ribosomes

Tiny particles composed of ribosomal RNA and protein that serve as the sites of protein synthesis in the cell.

Rough Endoplasmic Reticulum

A membrane-bound system of tunnels studded with ribosomes that synthesizes, folds, and exports proteins in transport vesicles.

Smooth Endoplasmic Reticulum

A membranous network lacking ribosomes that functions in lipid and steroid synthesis, lipid metabolism, and drug detoxification.

Golgi Apparatus

A stack of flattened membranous sacs that modifies, packages, and routes proteins received from the rough ER into secretory vesicles, lysosomes, or plasma membrane components.

Lysosomes

Membranous sacs containing powerful digestive enzymes (acid hydrolases) that digest worn-out cellular parts and foreign debris.

Peroxisomes

Membranous sacs containing oxidase and catalase enzymes that detoxify harmful substances like alcohol, neutralize free radicals, and break down hydrogen peroxide into water.

Cytoskeleton

An internal framework of protein structures (microfilaments, intermediate filaments, microtubules) extending throughout cytoplasm to maintain cell shape and enable movement.

Microfilaments

The thinnest cytoskeletal elements ($7\,nm$ in diameter), composed of the protein actin, involved in cell motility, shape changes, and muscle contraction.

Intermediate Filaments

Stable, fibrous cytoskeletal elements ($10\,nm$ in diameter) that anchor cellular structures and resist mechanical forces acting on the cell.

Microtubules

Cylindrical cytoskeletal structures ($25\,nm$ in diameter) composed of tubulin proteins that determine overall cell shape, direct organelle movement, and form centrioles, cilia, and flagella.

Centrioles

Rod-shaped organelles made of nine triplets of microtubules that generate spindle fibers during mitosis and form the base of cilia and flagella.

Cilia

Hairlike cellular extensions that move substances along the cell surface, such as propelling mucus out of the respiratory tract.

Flagella

Long, whip-like cellular extensions that propel an entire cell forward, found in humans exclusively on sperm cells.

Microvilli

Tiny, fingerlike projections of the plasma membrane that increase surface area for cellular absorption.

Fibroblast

An elongated connective tissue cell that secretes strong collagen fibers to connect body tissues.

Erythrocyte

A red blood cell lacking organelles that assumes a biconcave disc shape to transport oxygen throughout the cardiovascular system.

Macrophage

A phagocytic white blood cell equipped with pseudopods and lysosomes that engulfs and digests foreign pathogens and cellular debris.

Neuron

A specialized cell with long processes that receives, conducts, and transmits electrochemical signals throughout the nervous system.

Passive Transport

Cellular transport processes (such as simple diffusion, osmosis, facilitated diffusion, and filtration) that move substances across membranes without requiring cellular ATP.

Diffusion

The passive movement of molecules or ions down a concentration gradient from an area of high concentration to an area of lower concentration.

Osmosis

The simple diffusion of water molecules through aquaporin channel proteins across a selectively permeable membrane.

Isotonic Solution

A solution with equal solute concentration to that inside a cell, resulting in no net water gain or loss by the cell.

Hypertonic Solution

A solution containing a higher concentration of nonpenetrating solutes than the cell, causing water to leave the cell and the cell to shrink (crenate).

Hypotonic Solution

A solution containing a lower concentration of nonpenetrating solutes than the cell, causing water to flow into the cell and the cell to swell and potentially burst (lyse).

Facilitated Diffusion

Passive transport of large, lipid-insoluble, or charged solutes across a membrane down their concentration gradient using specific protein carriers or channels.

Filtration

A passive transport process in which fluid and solutes are forced across a membrane by hydrostatic (fluid) pressure along a pressure gradient.

Active Transport

The movement of substances across a plasma membrane against concentration or electrical gradients using solute pump carrier proteins and cellular ATP energy.

Sodium-Potassium Pump

An active transport carrier protein that hydrolyzes ATP to move three sodium ions ($Na^+$) out of the cell and two potassium ions ($K^+$) into the cell.

Exocytosis

An active vesicular transport process that secretes hormones, mucus, and cellular products by fusing intracellular vesicles with the plasma membrane.

Endocytosis

An active process in which extracellular substances are enclosed by plasma membrane pits and engulfed into intracellular membranous vesicles.

Phagocytosis

A type of endocytosis ('cell eating') where cytoplasmic pseudopods extend around large solid particles like bacteria or dead cells to enclose them in a vesicle.

Pinocytosis

A form of endocytosis ('cell drinking') where plasma membranes invaginate to take in small droplets of extracellular fluid containing dissolved nutrients.

Receptor-Mediated Endocytosis

A highly selective endocytosis mechanism where target molecules bind to specific plasma membrane receptors before being internalized in vesicles.

Interphase

The metabolic phase of the cell cycle during which the cell grows, performs normal functions, and replicates its DNA prior to division.

Mitosis

The division of the cell nucleus into two identical daughter nuclei containing complete sets of chromosomes.

Cytokinesis

The division of cytoplasm into two distinct daughter cells via a contractile ring cleavage furrow.

Prophase

The first phase of mitosis where chromatin condenses into sister chromatids joined at centromeres, nucleoli break down, nuclear envelope fragments, and spindle fibers form.

Metaphase

The stage of mitosis where chromosomes align along the metaphase plate across the center of the mitotic spindle.

Anaphase

The mitotic phase in which centromeres split and daughter chromosomes are pulled toward opposite cell poles by spindle fibers.

Telophase

The final stage of mitosis where chromosomes uncoil into chromatin, nuclear envelopes re-form, nucleoli reappear, and spindle structures break down.

Epithelial Tissue

An avascular primary tissue type that covers surfaces, lines body cavities and organs, forms glands, and functions in protection, absorption, filtration, and secretion.

Simple Epithelium

Epithelial tissue composed of a single cell layer anchored to a basement membrane, specialized for absorption, secretion, and diffusion.

Stratified Epithelium

Epithelial tissue consisting of two or more cell layers, designed primarily to protect underlying tissues from abrasion and mechanical stress.

Simple Squamous Epithelium

A single layer of flattened, scale-like epithelial cells forming membranes suited for rapid filtration and diffusion, such as in lung air sacs and capillaries.

Simple Cuboidal Epithelium

A single layer of cube-like cells with central nuclei that functions in secretion and absorption, found in kidney tubules and gland ducts.

Simple Columnar Epithelium

A single layer of tall cells lining the digestive tract from stomach to anus, often interspersed with mucus-secreting goblet cells.

Pseudostratified Columnar Epithelium

A single layer of columnar cells of varying heights giving a false appearance of multiple layers; ciliated forms line the human trachea to sweep mucus.

Stratified Squamous Epithelium

Multi-layered epithelium with flat surface cells, acting as a protective barrier in areas subject to friction like the skin, mouth, and esophagus.

Transitional Epithelium

A modified stratified squamous epithelium lining urinary system organs that stretches and flattens as organs fill with urine.

Endocrine Glands

Ductless glands that secrete chemical signals (hormones) directly into surrounding blood vessels.

Exocrine Glands

Glands that release their secretions through ducts onto epithelial surfaces, such as sweat, oil, and salivary glands.

Connective Tissue

The most widely distributed body tissue type that protects, supports, binds together, and cushions body structures, characterized by varying vascularity and an extracellular matrix.

Extracellular Matrix

Nonliving substance produced and secreted by connective tissue cells consisting of ground substance and collagen, elastic, or reticular fibers.

Osseous Tissue

Bone tissue composed of osteocytes residing in lacunae within a hard extracellular matrix of calcium salts and collagen fibers.

Hyaline Cartilage

The most widespread cartilage type, composed of chondrocytes in lacunae with hidden collagen fibers in a glassy rubbery matrix; found in trachea, rib attachments, and long bone ends.

Fibrocartilage

Highly compressible cartilage containing abundant collagen fibers, forming cushionlike discs between spinal vertebrae.

Dense Regular Connective Tissue

Connective tissue packed with parallel collagen fibers synthesized by fibroblasts, forming strong tendons (muscle-to-bone) and ligaments (bone-to-bone).

Areolar Connective Tissue

A soft, pliable packaging tissue containing all fiber types that cushions body organs and forms the lamina propria layer beneath mucous membranes.

Adipose Connective Tissue

Fat tissue dominated by adipocytes with stored lipid droplets that insulates, cushions organs, and stores metabolic fuel.

Reticular Connective Tissue

A network of interwoven reticular fibers that forms the internal supporting framework (stroma) for free blood cells in lymph nodes, spleen, and bone marrow.

Vascular Tissue

Blood tissue consisting of blood cells surrounded by a nonliving fluid matrix called plasma, transporting nutrients, wastes, and respiratory gases.

Skeletal Muscle Tissue

Voluntarily controlled muscle tissue attached to bones characterized by long, cylindrical, striated cells with multiple nuclei.

Cardiac Muscle Tissue

Involuntary striated muscle tissue found exclusively in the heart wall, composed of branching uninucleate cells connected by intercalated discs containing gap junctions.

Smooth Muscle Tissue

Involuntary, non-striated muscle tissue with spindle-shaped uninucleate cells found in walls of hollow organs like the stomach and intestine.

Neuroglia

Specialized supporting cells in nervous tissue that insulate, support, and protect fragile neurons.

Regeneration

The replacement of destroyed or damaged body tissue with the exact same functional cell type.

Fibrosis

The repair of tissue damage by dense fibrous connective tissue forming non-functional scar tissue.

Hyperplasia

An increase in the size of a tissue or organ caused by accelerated rates of cell division in response to local stimulation or irritation.

Atrophy

A reduction in the size of a tissue or organ resulting from loss of normal stimulation, usage, or nourishment.