Tissues – Epithelial & Connective (APC 3.2–3.3)

Vocabulary flashcards summarizing essential terms from the lecture on epithelial and connective tissues.

Tissue

A group of similar cells and their products working together to perform a unified function.

Histology

The scientific study and classification of tissues.

Extracellular Matrix (ECM)

Material surrounding cells; composed of ground substance and protein fibers.

Ground Substance

Fluid-to-solid portion of the ECM that houses fibers; ranges from liquid (blood) to solid (bone).

Collagen Fiber

Strong, rope-like protein fiber providing tensile strength to connective tissues.

Elastic Fiber

Protein fiber that can stretch and recoil, giving tissues flexibility.

Epithelial Tissue

Tissue type that covers surfaces, lines cavities, and forms secretory glands.

Connective Tissue

Tissue that fills spaces, provides support, stores energy, and has abundant ECM.

Muscle Tissue

Tissue specialized to contract and produce movement (skeletal, cardiac, smooth).

Neural Tissue

Tissue that conducts electrical impulses and carries information.

Polarity (Epithelia)

Structural difference between the apical (free) and basal (attached) surfaces of epithelium.

Apical Surface

The exposed or free surface of an epithelial sheet.

Basal Surface

The attached surface of epithelium anchored to underlying tissue or basal lamina.

Basal Lamina

Thin layer of ECM linking epithelium to underlying connective tissue.

Tight Junction

Cell junction that seals neighboring epithelial cells, preventing leakage between them.

Desmosome

Button-like junction that fastens cells together, providing mechanical strength.

Hemidesmosome

Junction anchoring epithelial cells to the basal lamina.

Avascular (Epithelia)

Lacking blood vessels; nutrients diffuse from underlying tissues.

Regeneration (Epithelia)

High mitotic rate allowing rapid replacement of damaged epithelial cells.

Exocrine Gland

Gland made of epithelial cells that secretes products onto a surface or into a duct.

Simple Epithelium

Single layer of epithelial cells; specialized for absorption, secretion, or diffusion.

Stratified Epithelium

Two or more layers of epithelial cells; specialized for protection.

Simple Squamous Epithelium

One thin layer of flat cells allowing rapid diffusion (e.g., alveoli, capillaries).

Simple Cuboidal Epithelium

Single layer of cube-shaped cells for secretion and absorption (e.g., kidney tubules).

Simple Columnar Epithelium

Single layer of tall cells providing thicker barrier; may have microvilli or cilia (e.g., small intestine).

Pseudostratified Columnar Epithelium

Single layer of varying-height cells appearing stratified; often ciliated in respiratory tract.

Stratified Squamous Epithelium

Multiple cell layers with flat apical cells; resists abrasion (skin, oral cavity).

Keratinized Epithelium

Stratified squamous epithelium whose surface cells are packed with keratin and dead (epidermis).

Nonkeratinized Epithelium

Stratified squamous epithelium with living surface cells (mouth, vagina).

Transitional Epithelium

Stratified tissue that stretches and changes shape (urinary bladder).

Mesenchyme

Embryonic tissue that gives rise to all connective tissue types.

Connective Tissue Proper

Category containing loose and dense connective tissues with viscous ground substance.

Loose Areolar Connective Tissue

Widely distributed CT with loosely arranged fibers; supports epithelia, cushions organs.

Adipose Tissue

Connective tissue dominated by adipocytes; stores fat, insulates, cushions.

Reticular Tissue

Loose CT with network of reticular fibers supporting lymphoid organs (spleen, nodes).

Dense Regular Connective Tissue

CT with parallel collagen fibers providing uni-directional tensile strength (tendons, ligaments).

Dense Irregular Connective Tissue

CT with random collagen bundles offering strength in multiple directions (dermis, periosteum).

Elastic Connective Tissue

CT rich in elastic fibers allowing stretch and recoil (walls of large arteries).

Cartilage

Supporting CT with semisolid matrix and chondrocytes in lacunae; avascular.

Chondrocyte

Cartilage cell residing in a small cavity called a lacuna.

Lacuna

Small space within cartilage or bone matrix housing a cell (chondrocyte or osteocyte).

Hyaline Cartilage

Most common cartilage with glossy matrix; forms embryonic skeleton, nose, trachea, articular surfaces.

Fibrocartilage

Cartilage with dense collagen bundles; resists compression (intervertebral discs, menisci).

Elastic Cartilage

Cartilage with elastic fibers for flexibility (external ear, epiglottis).

Bone (Osseous Tissue)

Supporting CT with solid, mineralized matrix; provides rigid support and stores minerals.

Blood

Fluid connective tissue whose matrix is plasma; transports gases, nutrients, wastes.

Lymph

Fluid CT composed of lymphatic fluid; returns excess tissue fluid to bloodstream.

Tendon

Dense regular CT structure attaching muscle to bone.

Ligament

Dense regular CT structure connecting bone to bone.

Dermis

Dense irregular CT layer beneath the epidermis of skin.

Periosteum

Dense irregular CT membrane covering bone surfaces.