Histology Lecture – Key Vocabulary

A comprehensive set of vocabulary flashcards covering major terms, cell types, tissues, junctions, glands, membranes, and processes discussed in Chapter 5: Histology.

Histology

The study of tissues and how they are arranged into organs.

Epithelial tissue

Tissue composed of closely packed cells that covers surfaces, lines cavities, and forms glands.

Connective tissue

Tissue with low cellularity and abundant extracellular matrix that supports, binds, and protects organs.

Nervous tissue

Tissue specialized for rapid communication by electrical and chemical signals.

Muscular tissue

Tissue composed of elongated, contractile cells that produce movement and heat.

Ectoderm

Outer primary germ layer that gives rise to epidermis and nervous system.

Endoderm

Inner primary germ layer that forms mucous membranes of digestive and respiratory tracts and associated glands.

Mesoderm

Middle germ layer that becomes mesenchyme and gives rise to muscle, bone, and blood.

Mesenchyme

Gelatinous embryonic connective tissue derived from mesoderm.

Apical surface

The exposed or free surface of an epithelial cell.

Basal surface

The side of an epithelial cell attached to the basement membrane.

Basement membrane

Layer of collagen and glycoproteins anchoring epithelium to underlying connective tissue.

Simple epithelium

An epithelium with a single layer of cells.

Stratified epithelium

An epithelium with two or more layers of cells.

Simple squamous epithelium

Single layer of thin, flat cells allowing rapid diffusion; lines alveoli, endothelium.

Simple cuboidal epithelium

Single layer of square or round cells for absorption and secretion; found in kidney tubules, glands.

Simple columnar epithelium

Single row of tall cells with oval nuclei; often contains microvilli or cilia and goblet cells.

Pseudostratified columnar epithelium

Appears multilayered but all cells touch basement membrane; ciliated with goblet cells in respiratory tract.

Goblet cell

Wine-glass-shaped mucus-secreting unicellular gland in some epithelia.

Keratinized stratified squamous epithelium

Multiple layers with dead, keratin-filled surface cells; forms epidermis and resists abrasion.

Nonkeratinized stratified squamous epithelium

Stratified squamous epithelium lacking dead surface cells; moist linings such as mouth, vagina.

Stratified cuboidal epithelium

Two or more layers of cube-shaped cells; lines sweat gland ducts, contributes to secretion.

Transitional epithelium

Stratified epithelium whose surface cells change shape when stretched; lines ureter and bladder.

Fibroblast

Connective tissue cell that produces fibers and ground substance.

Macrophage

Large phagocytic cell that engulfs pathogens and debris.

Leukocyte

White blood cell involved in immune defense.

Neutrophil

Type of leukocyte that phagocytizes bacteria.

Lymphocyte

White blood cell involved in adaptive immunity; includes B- and T-cells.

Plasma cell

Activated B-lymphocyte that secretes antibodies.

Adipocyte

Fat cell storing triglycerides.

Collagen fiber

Tough, flexible fiber made of collagen protein; most abundant body protein.

Reticular fiber

Thin collagen fiber coated with glycoprotein forming supportive networks.

Elastic fiber

Thin, stretchable fiber made of elastin providing elasticity.

Glycosaminoglycan (GAG)

Long polysaccharide in ground substance that attracts water; e.g., chondroitin sulfate.

Chondroitin sulfate

Most abundant GAG; contributes to cartilage stiffness.

Hyaluronic acid

Viscous GAG giving ground substance a slippery feel.

Proteoglycan

Large molecule with core protein and GAG bristles; binds tissues together.

Areolar tissue

Loose connective tissue with loosely arranged fibers and abundant ground substance.

Reticular tissue

Loose connective tissue of reticular fibers forming stroma of lymphatic organs.

Dense regular connective tissue

Connective tissue with parallel collagen fibers; forms tendons and ligaments.

Dense irregular connective tissue

Connective tissue with randomly arranged collagen fibers; resists unpredictable stress.

Adipose tissue

Connective tissue dominated by adipocytes; stores energy and insulates.

White fat

Most common adult adipose tissue for energy storage and cushioning.

Brown fat

Heat-generating adipose tissue in infants and hibernating animals.

Chondroblast

Cartilage-forming cell that secretes matrix before becoming chondrocyte.

Chondrocyte

Mature cartilage cell residing in a lacuna.

Lacuna

Small cavity housing a chondrocyte or osteocyte.

Perichondrium

Dense irregular connective tissue sheath surrounding most cartilage.

Hyaline cartilage

Most common cartilage; clear matrix, found in articular surfaces, trachea.

Elastic cartilage

Cartilage with elastic fibers; provides flexible support in ear, epiglottis.

Fibrocartilage

Cartilage with thick collagen bundles; resists compression in intervertebral discs.

Spongy bone

Porous osseous tissue with trabeculae; interior of bones.

Compact bone

Dense osseous tissue forming outer shell of bones.

Osteon

Structural unit of compact bone consisting of a central canal and concentric lamellae.

Osteocyte

Mature bone cell occupying a lacuna.

Canaliculi

Tiny channels connecting lacunae for nutrient exchange between osteocytes.

Periosteum

Tough fibrous connective tissue covering a bone.

Blood plasma

Liquid ground substance of blood.

Erythrocyte

Red blood cell that transports oxygen and carbon dioxide.

Platelet

Cell fragment involved in blood clotting.

Excitability

Ability of a cell to respond to stimuli with electrical changes.

Neuron

Nerve cell specialized for rapid communication.

Neurosoma

Cell body of a neuron containing the nucleus.

Dendrite

Branched neuronal process that receives signals.

Axon

Single long neuronal process that transmits signals away from the cell body.

Neuroglia

Supporting cells of nervous tissue that protect and assist neurons.

Skeletal muscle

Striated, multinucleate, voluntary muscle attached to bones.

Cardiac muscle

Striated, branched, involuntary muscle of the heart with intercalated discs.

Smooth muscle

Non-striated, involuntary muscle in viscera and blood vessels.

Intercalated disc

Gap junction and desmosome-rich connection between cardiac muscle cells.

Tight junction

Intercellular junction that seals neighboring cells to prevent leakage.

Desmosome

Spotlike junction that mechanically links cells together.

Hemidesmosome

Anchor connecting epithelial cells to the basement membrane.

Gap junction

Communicating junction formed by connexons allowing ions to pass.

Gland

Organ or cell that secretes substances for use or excretion.

Exocrine gland

Gland that releases secretion through a duct to a surface.

Endocrine gland

Ductless gland that releases hormones into the bloodstream.

Merocrine secretion

Release of product by exocytosis without loss of cytoplasm.

Apocrine gland

Gland whose secretions are released with portions of apical cytoplasm; axillary sweat glands.

Holocrine secretion

Mode in which entire cells disintegrate to release product; sebaceous glands.

Serous gland

Gland producing thin, watery secretions like sweat or tears.

Mucous gland

Gland producing mucus-rich, viscous secretions.

Cutaneous membrane

The skin; stratified squamous epithelium over connective tissue.

Mucous membrane

Epithelium over lamina propria lining passages opening to exterior.

Serous membrane

Simple squamous epithelium on areolar tissue that secretes serous fluid.

Synovial membrane

Connective tissue lining joint cavities, secreting synovial fluid.

Hyperplasia

Tissue growth through increase in cell number.

Hypertrophy

Growth due to enlargement of existing cells.

Neoplasia

Abnormal tissue growth resulting in a tumor.

Differentiation

Process by which immature cells become specialized.

Metaplasia

Transformation of one mature tissue type into another.

Stem cell

Undifferentiated cell capable of giving rise to specialized cells.

Totipotent

Stem cell able to form any cell type, including embryonic tissues.

Pluripotent

Stem cell able to form any cell of the embryo proper.

Multipotent

Adult stem cell able to produce multiple related cell types.

Unipotent

Stem cell producing only one cell type.

Regeneration

Replacement of damaged tissue with the same type restoring function.

Fibrosis

Replacement of damaged tissue with scar tissue losing normal function.

Granulation tissue

Vascular, fibroblast-rich tissue formed during wound healing.

Atrophy

Shrinkage of tissue due to cell loss or size reduction.