Tissue Level Organization

Vocabulary flashcards covering epithelial, connective, muscle, and membrane tissues based on the Chapter 1-8 lecture transcript.

Tissue

A collection of specialized cells and cell products that perform specific functions, representing the next level of organization up from individual cells.

Organ

A body structure composed of at least two or more tissues performing specific collective functions.

Epithelial Tissue

A basic tissue type consisting of layers of cells that cover internal and external surfaces, line organs, and form glands.

Connective Tissue

The largest basic tissue type that fills internal spaces, provides structural framework, transports materials, and connects other tissues.

Muscle Tissue

A basic tissue type specialized for contraction to perform work in the body.

Nervous Tissue

A basic tissue type specialized for carrying electrical signals from one part of the body to another for sensation and action.

Apical Surface

The exposed upper surface or apex of an epithelial cell that faces the internal or external environment.

Basal Surface

The bottom region of an epithelial cell attached to the underlying basement membrane and connective tissue.

Reticular Lamina

The deepest part of the basement membrane containing net-like reticular fibers in a ground substance that provides structural strength.

Microvilli

Protrusions on the apical surface of epithelial cells that increase total surface area for absorption and secretion.

Cell Adhesion Molecules (CAMs)

Transmembrane proteins that link adjacent epithelial cells across their cell membranes.

Gap Junctions

Cell junctions where plasma membranes are held together by hollow transmembrane proteins called nexons, creating a channel for small molecules and ions to pass.

Tight Junctions

Junctions formed by interlocking junctional proteins that prevent fluids and solutes from diffusing between adjacent cells.

Desmosomes

Strong cell junctions formed by cell adhesion molecules and proteoglycans linked to the intermediate filaments of the cell cytoskeleton.

Hemidesmosomes

Structures resembling half of a spot desmosome that anchor an epithelial cell to extracellular structures in the basement membrane.

Squamous Epithelium

Epithelium characterized by thin, flat, scale-shaped cells.

Cuboidal Epithelium

Epithelium characterized by cells that are cube-shaped or square in appearance.

Columnar Epithelium

Epithelium characterized by tall, slender, rectangular pillar-like cells.

Simple Epithelium

Epithelium consisting of a single layer of cells covering the basement membrane.

Stratified Epithelium

Epithelium consisting of multiple stacked layers of cells covering the basement membrane.

Mesothelium

The simple squamous epithelium that lines the internal body cavities.

Endothelium

The simple squamous epithelium lining the inside of the heart and blood vessels.

Keratinization

The process of incorporating the protein keratin into stratified squamous cells to add strength and water resistance.

Transitional Epithelium

Specialized epithelium in the urinary system that changes shape, appearing stratified squamous when stretched and cuboidal when relaxed.

Pseudostratified Columnar Epithelium

Epithelium lining respiratory passages that appears stratified due to non-aligned cell nuclei, specialized in secreting mucus.

Endocrine Glands

Ductless glands that release hormones directly into the bloodstream.

Exocrine Glands

Glands that discharge secretions onto epithelial surfaces or into target organs through ducts.

Goblet Cells

Unicellular exocrine glands located in the intestinal epithelium that secrete mucin.

Mucus Cells

Unicellular exocrine glands located in the tracheobronchial airways that secrete mucin to form mucus.

Merocrine Secretion

A mode of exocrine secretion where product-containing vesicles fuse with the plasma membrane to release contents without damaging the cell (also called eccrine secretion).

Apocrine Secretion

A mode of exocrine secretion where a portion of the cell cytoplasm containing secretions buds off, after which the cell repairs itself.

Holocrine Secretion

A mode of exocrine secretion where the superficial gland cell bursts and dies to release its contents, requiring replacement by stem cells.

Ground Substance

The clear, colorless, viscous fluid component of the connective tissue matrix that fills spaces between cells and slows pathogen movement.

Matrix

The extracellular structural material surrounding connective tissue cells, composed of extracellular protein fibers and ground substance.

Fibroblasts

Specialized connective tissue cells responsible for secreting connective tissue fibers and matrix components.

Adipocytes

Fat cells that store energy as single lipid droplets.

Mesenchymal Cells

Stem cells present in connective tissue proper capable of differentiating into various connective tissue cells.

Melanocytes

Specialized connective tissue cells responsible for producing and storing the pigment melanin.

Collagen Fibers

Thick, strong, straight, and flexible protein fibers found in abundance within tendons and ligaments.

Reticular Fibers

Thin, flexible protein fibers arranged in a crosshatched net-like meshwork that forms the supportive framework of organs.

Elastic Fibers

Wavy, branching, stretchy protein fibers composed primarily of the protein elastin.

Areolar Tissue

A loose connective tissue with an unspecialized open structure and viscous ground substance that cushions organs and anchors epithelial tissues.

White Fat

Adipose tissue that stores energy in single lipid droplets and provides insulation under the skin and around organs.

Brown Fat

Vascularized adipose tissue rich in mitochondria found in infants and children that breaks down fat directly to produce heat.

Dense Regular Connective Tissue

Connective tissue filled with parallel, densely packed collagen fibers that resist force along a single axis, found in tendons and ligaments.

Dense Irregular Connective Tissue

Connective tissue consisting of an interwoven network of collagen fibers running in multiple directions, found in the dermis and periosteum.

Dense Elastic Connective Tissue

Dense connective tissue dominated by elastic fibers that allows expansion and contraction in large blood vessels and spinal ligaments.

Tendons

Dense regular connective tissue cords that attach skeletal muscles to bones.

Ligaments

Dense regular connective tissue structures that connect bone to bone or hold organs in place.

Aponeurosis

A broad, sheet-like dense regular connective tissue tendon bundle that anchors muscle groups in the palms and soles.

Periosteum

A layer of dense irregular connective tissue that surrounds and protects the outer surface of bones.

Superficial Fascia

A layer of loose areolar and adipose tissue between the skin and underlying muscle organs.

Deep Fascia

Sheets of dense irregular connective tissue that wrap around individual muscles, joint capsules, and internal organs.

Hyaline Cartilage

The most common type of cartilage, composed of closely packed collagen fibers, providing stiff but flexible support at joints and respiratory passages.

Elastic Cartilage

Highly flexible cartilage dominated by elastic fibers, located in the external ear and epiglottis.

Fibrocartilage

Extremely durable cartilage with interwoven collagen fibers that absorbs mechanical shock between intervertebral discs and pelvic bones.

Lacunae

Small pockets or chambers within bone or cartilage matrices that enclose osteocytes or chondrocytes.

Canaliculi

Microscopic channels through calcified bone matrix that allow blood nutrients and wastes to pass between osteocytes and central canals.

Lamina Propria

The layer of loose areolar tissue that forms the basement membrane support of mucous membranes.

Parietal Layer

The portion of a serous membrane that lines the inner surface of a body cavity wall.

Visceral Layer

The portion of a serous membrane that directly covers the outer surfaces of internal organs.

Synovial Membrane

A membrane composed of areolar tissue and an incomplete nonpolar epithelium that lines joint cavities and secretes lubricating synovial fluid.

Skeletal Muscle Tissue

Striated, voluntary muscle tissue containing long, multinucleated fibers responsible for body movement.

Cardiac Muscle Tissue

Striated, involuntary muscle tissue composed of short, branched single-nucleated cells found in the heart wall.

Smooth Muscle Tissue

Non-striated, involuntary muscle tissue containing single-nucleated cells capable of dividing, lining internal organs and blood vessels.