Histology and Tissue Organization Flashcards

Comprehensive vocabulary flashcards covering Chapter 5: Tissue Organization (Histology), including epithelial, connective, muscle, and nervous tissues, glands, membranes, and tissue repair mechanisms.

Histology

The study of tissues in the body.

Epithelial tissue

A basic tissue type that covers exposed surfaces, lines internal cavities and passageways, and forms glands.

Connective tissue

A basic tissue type that supports and protects other tissues, binds structures together, transports materials, and stores energy.

Muscular tissue

A basic, excitable, and well-vascularized tissue type specialized for contraction, comprising skeletal, heart, and smooth muscle.

Nervous tissue

A basic tissue type specialized for electrical impulse generation and signal transmission.

Primary germ layers

The three embryonic layers (ectoderm, endoderm, and mesoderm) from which all body tissues are derived.

Tight junctions

Intercellular junctions formed by interlocking proteins and an adhesion belt that seal membranes together, preventing passage of water and solutes to control permeability.

Desmosomes

Intercellular junctions formed by protein plaques and filaments that interlock cytoskeletons to provide durable connections capable of resisting mechanical stresses.

Button desmosome

A type of desmosome that acts as a cell-to-cell cross brace.

Hemidesmosome

A type of desmosome that anchors epithelial cells to the underlying basement membrane.

Gap junctions

Intercellular channels formed by rings of connexons that permit direct cytoplasm-filled passage of small ions, solutes, and electrical signals between adjacent cells.

Connexons

Rings of transmembrane proteins that assemble to form gap junction channels between cells.

Simple epithelium

Epithelial tissue composed of a single cell layer; fragile and specialized for absorption, secretion, and filtration.

Stratified epithelium

Epithelial tissue consisting of two or more cell layers; durable and located in areas subject to mechanical or chemical stress.

Simple squamous epithelium

The thinnest and most delicate epithelia, composed of a single layer of flat cells resembling fried eggs, specialized for absorption and secretion.

Endothelium

The specialized simple squamous epithelium lining the inner walls of the heart and blood vessels.

Mesothelium

The specialized simple squamous epithelium (serosa) lining the pericardial and peritoneal cavities.

Simple cuboidal epithelium

A single layer of isodiametric (cube-shaped) cells functioning in secretion and absorption, found in kidney, thyroid, and liver tissues.

Simple columnar epithelium

A single layer of tall, narrow cells specialized for absorption and secretion, common in the gastrointestinal tract and endocervical canal.

Pseudostratified columnar epithelium

A single-layered epithelium appearing to have multiple layers of tall, narrow cells, specialized for secretion and ciliary movement in the respiratory tract and uterine tubes.

Stratified squamous epithelium

The toughest multi-layered epithelia designed to protect underlying tissues against physical and chemical attacks.

Keratinized stratified squamous epithelium

Stratified squamous epithelia containing keratin for added strength and water resistance, located on the surface of the skin.

Non-keratinized stratified squamous epithelium

Stratified squamous epithelia lacking keratin, lining moist surfaces such as the oral cavity, esophagus, anus, and vagina.

Transitional epithelium

A specialized stratified epithelium capable of stretching and recoiling, whose apical cells shift from round to flat when distended; found in ureters, urinary bladder, and parts of the urethra.

Endocrine glands

Ductless glands that release secretions (such as hormones) directly into surrounding interstitial fluid.

Exocrine glands

Glands with ducts that discharge secretions onto an epithelial surface, such as skin or digestive tract linings.

Merocrine glands

Glands that release secretions through exocytosis using vesicles without losing cell cytoplasm, representing the most common mode of secretion.

Apocrine glands

Modified merocrine glands where apical cytoplasm is shed along with the secretional product (e.g., mammary glands, armpit sweat glands).

Holocrine glands

Glands whose secretory products accumulate in the cytoplasm and are released through cell autolysis, killing the cells which are continuously replaced by stem cells.

Fibroblasts

Abundant connective tissue cells that produce matrix fibers and ground substance, eventually differentiating into fibrocytes.

Adipocytes

Fat cells specialized for storing lipids, pushing organelles to the periphery of the cell cytoplasm.

Macrophages

Immune connective tissue cells that phagocytize foreign material and damaged cells, existing as fixed or migrating free cells.

Mast cells

Connective tissue cells that secrete proinflammatory molecules, inhibit clotting, and dilate blood vessels.

Collagen fibers

Long, straight, cable-like white fibers made of collagen; strong, flexible, and stretch-resistant fibers that resist force in one direction.

Reticular fibers

Thin, branching collagenous fibers that form flexible interwoven networks to resist force in many directions.

Elastic fibers

Thin, branching, wavy yellow fibers containing elastin protein that easily stretch and recoil.

Areolar tissue

A highly vascular, least-specialized loose connective tissue with an open arrangement of collagen and elastic fibers in abundant ground substance, underlying all epithelia.

Adipose tissue

Vascularized loose connective tissue composed of adipocytes, functioning in energy storage, insulation, cushioning (white fat), or heat production (brown fat).

Reticular tissue

Loose connective tissue consisting of a mesh network of reticular fibers housing leukocytes, forming the stroma of lymphatic organs.

Dense regular connective tissue

Connective tissue made of tightly packed parallel collagen fibers with little ground substance, providing attachment and resisting stress in one direction.

Dense irregular connective tissue

Connective tissue with densely packed, randomly arranged collagen fiber bundles that withstand stress in multiple directions and resist tearing.

Chondrocytes

Cartilage cells housed within small matrix spaces called lacunae.

Chondroblasts

Cells that actively produce cartilage extracellular matrix, becoming chondrocytes once enclosed by matrix.

Hyaline cartilage

Cartilage containing dispersed collagen fibers that provides stiff, semi-flexible support at synovial joints, rib tips, sternum, and trachea.

Fibrocartilage

Durable cartilage with dense collagen fibers that resists compression and bears weight in the pubic symphysis, meniscus, and intervertebral discs.

Elastic cartilage

Flexible cartilage containing dense elastic fibers that provides springy support in the external ear and epiglottis.

Osteocytes

Mature bone cells located in lacunae within calcified bone matrix.

Canaliculi

Small passageways branching through hard bone matrix that connect osteocytes to central blood and nerve supplies.

Mucous membranes

Internal membranes lining body passageways open to the exterior, composed of an epithelium and an underlying areolar lamina propria layer.

Lamina propria

The layer of areolar connective tissue that supports the epithelial tissue in mucous membranes.

Serous membranes

Internal double membranes (visceral and parietal layers) lining closed body cavities, secreting serous fluid to eliminate internal friction.

Cutaneous membrane

The skin; a thick, dry, water-resistant membrane composed of an epidermal layer of keratinized stratified squamous epithelium and a connective tissue dermis.

Synovial membranes

Acellular connective tissue membranes lining articulating joint cavities that produce lubricating synovial fluid.

Skeletal muscle

Voluntary muscle tissue consisting of long, cylindrical, striated cells with multiple peripheral nuclei that do not divide.

Cardiac muscle

Involuntary striated muscle tissue found exclusively in the heart, consisting of short, branching cells with single nuclei, pacemaker cells, and intercalated discs.

Intercalated discs

Specialized cell junctions connecting adjacent cardiac muscle cells.

Smooth muscle

Involuntary, non-striated muscle tissue made of short, spindle-shaped cells with single nuclei that can divide and easily repair.

Neuron

An excitable nervous system cell specialized for transmitting electrical signals, consisting of a soma, dendrites, and an axon.

Soma

The cell body of a neuron containing its nucleus and nucleolus.

Dendrites

Short branching extensions of the neuron soma that receive incoming electrical signals.

Axon

A long, thin extension of the neuron soma that conducts outgoing nerve impulses.

Neuroglia

Glial cells that protect, support, nourish, and repair the tissue framework around neurons.

Hypertrophy

Tissue expansion caused by an increase in individual cell size.

Hyperplasia

Tissue growth caused by an increase in total cell number via multiplication.

Metaplasia

An adaptive tissue transformation in which one cell type transforms into another.

Dysplasia

Abnormal tissue growth that may revert to normal or progress abnormally.

Neoplasia

Uncontrolled, abnormal, non-functional tissue proliferation forming benign or malignant growths.

Atrophy

The shrinkage of tissue caused by a loss of cell size or cell number.

Necrosis

Pathological tissue death resulting from an insufficient blood supply.

Apoptosis

Genetically programmed cellular suicide.

Regeneration

The process of tissue repair wherein damaged tissue is replaced with original cell types, restoring functional homeostatic capacity.

Fibrosis

The tissue repair process where damaged cells are replaced with collagenous scar tissue, failing to restore functional capability.