Chapter 4: The Tissue Level of Organization Flashcards

Vocabulary practice flashcards covering key definitions, cell types, structures, and concepts from Chapter 4 (The Tissue Level of Organization).

Histology

The study of the structure of tissues.

Epithelial tissue

Tissue type that covers exposed surfaces, lines internal passageways, and forms glands.

Connective tissue

Tissue type that fills internal spaces, supports other tissues, transports material, and stores energy.

Muscle tissue

Tissue type specialized for contraction to produce movement.

Nervous tissue

Tissue type that carries electrical signals from one part of the body to another.

Apical surface

The exposed surface of an epithelium facing an internal or external environment.

Basal surface

The attached surface of an epithelium bound to a noncellular basement membrane.

Cell adhesion molecules (CAMs)

Transmembrane proteins that attach opposing plasma membranes to each other and to the extracellular matrix.

Gap junctions

Intercellular connections held together by connexons that permit the free diffusion of ions and small molecules between cells.

Connexons

Interlocking transmembrane proteins that form gap junctions between adjacent cells.

Tight junctions

Intercellular connections formed by the fusion of outer membrane layers that prevent the diffusion of fluids and solutes between cells.

Adhesion belt

A continuous band deep to a tight junction that attaches cells to the microfilaments of the terminal web.

Desmosomes

Intercellular connections where CAMs and proteoglycans link opposing plasma membranes.

Spot desmosomes

Small disc-shaped junctional structures that tie adjacent cells together and stabilize cell shape.

Hemidesmosomes

Junctions that attach a cell to extracellular structures, such as protein fibers in the basement membrane.

Basal lamina

The amorphous layer of the basement membrane closest to the epithelium that acts as a selective filter.

Reticular lamina

The deeper portion of the basement membrane consisting of reticular fibers and ground substance that provides strength.

Mesothelium

Simple squamous epithelium lining the pericardial, pleural, and peritoneal cavities.

Endothelium

Simple squamous epithelium lining the inner surface of the heart and blood vessels.

Transitional epithelium

Epithelium that tolerates repeated cycles of stretching without damage, lining the urinary bladder, renal pelvis, and ureters.

Pseudostratified columnar epithelium

Ciliated epithelium that appears layered but is composed of a single layer of cells, lining the nasal cavity, trachea, and bronchi.

Endocrine glands

Ductless glands that release hormones directly into the bloodstream.

Exocrine glands

Glands that discharge secretions onto epithelial surfaces through ducts.

Goblet cells

Unicellular exocrine glands in epithelia of the intestines that secrete mucin.

Merocrine secretion

Secretion mode where product is released from secretory vesicles at the apical surface by exocytosis.

Apocrine secretion

Secretion mode involving the loss of apical cytoplasm containing secretory vesicles and inclusions.

Holocrine secretion

Secretion mode in which product is released as superficial gland cells burst and die.

Matrix

The extracellular component of connective tissue consisting of protein fibers and ground substance.

Fibroblasts

The most abundant fixed cells in connective tissue proper that secrete ground substance components and protein fibers.

Fibrocytes

The second most abundant cell type in connective tissue proper that maintains connective tissue fibers.

Adipocytes

Fat cells in connective tissue that each store a single, large fat droplet.

Mesenchymal cells

Stem cells in connective tissue that respond to injury or infection by differentiating into fibroblasts, macrophages, or other cell types.

Melanocytes

Connective tissue cells that synthesize and store the brown pigment melanin.

Macrophages

Large phagocytic immune system cells in connective tissue that engulf pathogens and damaged cells.

Mast cells

Connective tissue immune cells that release histamine and heparin to stimulate inflammation after injury or infection.

Histamine

Chemical released by mast cells that stimulates inflammation after injury or infection.

Heparin

An anticoagulant chemical released by mast cells to prevent blood clotting.

Collagen fibers

Long, straight, unbranched fibers in connective tissue proper that are strong and flexible, providing strength to tendons and ligaments.

Reticular fibers

Branching networks of interwoven fibers (stroma) that resist forces in multiple directions and stabilize cell positions.

Elastic fibers

Branched and wavy fibers containing the protein elastin that return to their original length after stretching.

Ground substance

A clear, colorless, and viscous fluid that fills spaces between cells and slows pathogen movement in connective tissue.

Mesenchyme

The first embryonic connective tissue to appear in an embryo, giving rise to all other connective tissues.

Areolar tissue

Least specialized adult loose connective tissue containing loosely organized cells and fibers in an open framework.

Adipose tissue

Loose connective tissue dominated by adipocytes that provides padding, shock absorption, insulation, and energy storage.

Reticular tissue

Loose connective tissue rich in reticular fibers that provides a supporting framework (stroma) for organs such as the liver, kidney, and spleen.

Dense regular connective tissue

Connective tissue made of parallel, tightly packed collagen fibers providing firm attachment in tendons, ligaments, and aponeuroses.

Tendons

Dense regular connective tissues that attach skeletal muscles to bones.

Ligaments

Dense regular connective tissues that connect one bone to another or stabilize internal organs.

Aponeuroses

Tendinous sheets that attach a broad, flat muscle to another structure.

Dense irregular connective tissue

Connective tissue with an interwoven network of collagen fibers that provides strength to resist forces from many directions.

Superficial fascia

Layer of areolar and adipose tissue (subcutaneous layer) that separates skin from underlying tissues.

Deep fascia

Sheets of dense regular connective tissue forming capsules around organs, muscles, cartilage, and bones.

Subserous fascia

Layer of areolar tissue lying between deep fascia and serous membranes.

Red blood cells (erythrocytes)

Anucleate formed elements in blood that transport oxygen and carbon dioxide.

White blood cells (leukocytes)

Nucleated formed elements in blood that defend the body against infection and disease.

Platelets

Membrane-enclosed packets of cytoplasm involved in blood clotting.

Lymph

Fluid connective tissue formed as interstitial fluid enters lymphatic vessels.

Chondrocytes

Cartilage cells residing in small matrix chambers called lacunae.

Lacunae

Small chambers in the matrix of cartilage or bone that house cells such as chondrocytes or osteocytes.

Perichondrium

Membrane surrounding cartilage with an outer fibrous layer for support and an inner cellular layer for growth and maintenance.

Hyaline cartilage

Most common cartilage type, containing closely packed collagen fibers that provide stiff but flexible support.

Elastic cartilage

Extremely flexible cartilage containing elastic fibers in its matrix, found in the external ear and larynx.

Fibrocartilage

Durable cartilage dominated by densely interwoven collagen fibers that resists compression between vertebrae, pubic bones, and knee joints.

Interstitial growth

Cartilage growth mechanism where chondrocytes divide within lacunae and secrete matrix, expanding cartilage from within.

Appositional growth

Cartilage growth mechanism where stem cells in the perichondrium differentiate into chondroblasts, adding new matrix to the outer surface.

Osteocytes

Mature bone cells located in lacunae within calcified matrix.

Canaliculi

Small channels through bone matrix that allow exchange of materials between osteocytes and central canals.

Periosteum

Membrane covering bone containing an outer fibrous layer and inner cellular layer.

Mucous membranes (mucosae)

Tissue membranes lining passageways that open to the exterior, lubricated by mucus and supported by lamina propria.

Lamina propria

The layer of areolar connective tissue supporting the epithelium in a mucous membrane.

Serous membranes

Membranes consisting of mesothelium supported by areolar tissue that line internal trunk cavities and secrete serous fluid.

Cutaneous membrane

Skin covering the body surface, consisting of keratinized stratified squamous epithelium and underlying connective tissues.

Synovial membranes

Tissue membranes lining joint cavities that produce synovial fluid to lubricate moving joints.

Skeletal muscle tissue

Striated, voluntary muscle tissue consisting of long, cylindrical multinucleate cells called muscle fibers.

Myosatellite cells

Muscle stem cells that divide to produce new skeletal muscle fibers.

Cardiac muscle tissue

Striated, involuntary muscle tissue found in the heart, consisting of short, branched cells connected by intercalated discs.

Intercalated discs

Specialized cell connections linking cardiac muscle cells that contain proteoglycans, desmosomes, and gap junctions.

Smooth muscle tissue

Nonstriated, involuntary muscle tissue composed of short, spindle-shaped cells with a central nucleus.

Neurons

Nerve cells specialized for conducting electrical impulses from one part of the body to another.

Neuroglia

Supporting cells in nervous tissue that maintain structure, repair tissues, perform phagocytosis, and provide nutrients to neurons.

Dendrites

Short branching processes extending from a neuron cell body that receive incoming signals.

Axon

Long process of a neuron that conducts outgoing electrical impulses to other cells.

Necrosis

Tissue death caused by physical trauma, injury, or lysosomal enzyme release.

Abscess

An accumulation of pus, fluids, debris, and dying cells in injured tissue.

Fibrosis

The process of replacing damaged functional tissue with non-functional fibrous scar tissue.