Histology: Epithelial, Connective, Muscle, and Nervous Tissues (HLTH115)

A vocabulary deck covering key histology terms from the notes, focusing on epithelial, connective, muscle, and nervous tissues.

Tissue

Groups of similar cells and extracellular material that perform a common function.

Histology

The study of tissues.

Epithelial tissue

Tissue made of tightly packed cells that covers surfaces, lines cavities, and forms glands; avascular with high regeneration.

Apical surface

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

Basal surface

The side of an epithelium attached to the underlying connective tissue.

Basement membrane

Barrier between epithelium and connective tissue, consisting of lamina lucida, lamina densa, and reticular lamina.

Lamina lucida

Thin, clear layer of the basement membrane adjacent to epithelium.

Lamina densa

Dense layer of the basement membrane rich in collagen.

Reticular lamina

Basement membrane layer containing reticular fibers, underlying the basal lamina.

Avascularity

Lack of blood vessels in epithelial tissue; nutrients diffuse from surfaces or underlying tissue.

Innervation

Nerve supply to a tissue; epithelia are often richly innervated to detect changes.

Regeneration

High rate of cell division to replace lost or damaged cells.

Simple epithelium

One cell layer thick; all cells contact the basement membrane.

Stratified epithelium

Two or more layers; only basal layer contacts the basement membrane; protective in function.

Pseudostratified epithelium

Appears layered due to nuclei at different levels, but all cells contact the basement membrane.

Squamous

Flat, wide epithelial cells.

Cuboidal

Epithelial cells about as tall as they are wide.

Columnar

Epithelial cells taller than they are wide.

Transitional epithelium

Epithelium that changes shape with stretch; lines urinary bladder.

Keratinized

Stratified squamous with superficial dead cells filled with keratin (as in skin).

Nonkeratinized

Stratified squamous with living surface cells (moist); lines mouth, esophagus, vagina, anus.

Gland

Individual cells or multicellular organs that secrete substances.

Endocrine gland

Gland lacking ducts; secretes hormones into the bloodstream.

Exocrine gland

Gland with ducts that secrete onto a surface or lumen.

Unicellular exocrine gland

Single secretory cell, e.g., goblet cell.

Multicellular exocrine gland

Gland with many cells forming secretory units (acini) and ducts.

Acinus

Secretory portion of a multicellular exocrine gland.

Duct

Conducting portion that carries secretions to the epithelial surface.

Merocrine secretion

Secretions released by vesicles through exocytosis.

Apocrine secretion

Apical portion pinches off to release secretion; repair occurs; e.g., mammary glands.

Holocrine secretion

Secretions formed from rupture of entire secretory cells; e.g., sebaceous glands.

Connective tissue

Most diverse tissue; supports, protects, binds organs; composed of cells, fibers, and ground substance.

Ground substance

Noncellular material produced by CT cells; varies from viscous to solid.

Extracellular matrix

Ground substance plus protein fibers surrounding CT cells.

Resident cells

Stationary CT cells that support, maintain, and repair tissue (e.g., fibroblasts, adipocytes, mesenchymal cells, fixed macrophages).

Wandering cells

CT cells that move through tissue to participate in immune defense (e.g., leukocytes, plasma cells, mast cells, macrophages).

Fibroblast

Most abundant resident CT cell; synthesizes fibers and ground substance.

Adipocyte

Fat cell; stores fat; found in adipose tissue.

Mesenchymal cell

Embryonic stem cell in CT; can differentiate into other CT cell types.

Fixed macrophage

Resident CT cell that phagocytizes debris and pathogens.

Mast cell

Wandering CT cell that releases histamine and heparin.

Plasma cell

B-lymphocyte-derived cell that produces antibodies.

Dense connective tissue

CT with mostly protein fibers and less ground substance; includes dense regular, dense irregular, and elastic types.

Dense regular connective tissue

Parallel collagen fibers; resists stress in one direction; found in tendons and ligaments.

Dense irregular connective tissue

Collagen fibers in many directions; durable and protective; found in dermis and organ capsules.

Elastic connective tissue

Dense tissue with many elastic fibers; allows stretch and recoil.

Cartilage

Firm, semisolid CT with chondrocytes in lacunae; avascular; three types: hyaline, fibrocartilage, elastic.

Hyaline cartilage

Most common cartilage; glassy matrix; chondrocytes in lacunae; perichondrium.

Fibrocartilage

Weight-bearing cartilage with dense collagen; no perichondrium; e.g., intervertebral discs.

Elastic cartilage

Cartilage with abundant elastic fibers; resilient; perichondrium; found in external ear and epiglottis.

Bone

Rigid connective tissue with organic and inorganic components; osteocytes in lacunae; compact and spongy types.

Compact bone

Dense bone with osteons, central canals, and lamellae.

Spongy bone

Lattice-like bone with trabeculae and marrow; lighter than compact bone.

Osteocyte

Bone cell housed in a lacuna within the mineralized matrix.

Osteon

Structural unit of compact bone with concentric lamellae around a central canal.

Central canal

Haversian canal in an osteon containing blood vessels and nerves.

Canaliculi

Tiny channels connecting lacunae to each other and to the central canal.

Blood

Fluid CT with formed elements (erythrocytes, leukocytes, platelets) and plasma.

Erythrocyte

Red blood cell; carries oxygen and carbon dioxide.

Leukocyte

White blood cell; immune defense; includes neutrophils, lymphocytes, etc.

Platelet

Cell fragment aiding in blood clotting.

Lymph

Fluid CT derived from plasma; contains no cells; returns to bloodstream.

Muscle tissue

Tissue of contractile cells enabling movement; three types: skeletal, cardiac, smooth.

Skeletal muscle

Striated, voluntary muscle; moves bones; long multinucleated fibers.

Cardiac muscle

Involuntary, striated muscle of the heart; intercalated discs; pumps blood.

Smooth muscle

Involuntary, nonstriated muscle; spindle-shaped cells in walls of hollow organs.

Nervous tissue

Tissue containing neurons and glial cells; transmits and processes nerve impulses.

Neuron

Nerve cell with a cell body, dendrites, and an axon.

Dendrite

Neuron process that receives signals.

Axon

Neuron process that transmits signals away from the cell body.

Glial cells

Supportive cells that nourish, protect, and support neurons.

Intercalated disc

Specialized junctions between cardiac muscle cells that strengthen connections and enable rapid conduction.

Lacuna

Small space that houses a cell (chondrocyte or osteocyte) in cartilage or bone.

Chondrocyte

Cartilage cell residing in a lacuna.

Perichondrium

Dense irregular CT covering cartilage.