Histology: Primary Tissues and Epithelial, Connective, Muscle, Nervous Tissues

Vocabulary flashcards covering key terms related to tissues, epithelial and connective tissues, muscle and nervous tissues, and tissue repair.

Cell specialization

The process by which cells develop unique structures and functions to perform specific tasks that maintain homeostasis.

Tissue

A group of cells similar in structure that perform a common or related function.

Histology

The study of tissues.

Epithelial tissue

Tissue that covers surfaces and lines cavities; includes covering/lining epithelia and glandular epithelia.

Connective tissue

Tissue that supports, binds, and protects other tissues; includes bone, cartilage, blood, and connective tissue proper.

Muscle tissue

Tissue that contracts to produce movement; includes skeletal, cardiac, and smooth muscle.

Nervous tissue

Tissue that regulates and controls body activities; composed of neurons and neuroglia.

Simple epithelium

Epithelium with a single cell layer.

Stratified epithelium

Epithelium with two or more cell layers; primarily for protection.

Squamous epithelium

Epithelial cells that are flat and scale-like.

Cuboidal epithelium

Epithelial cells that are boxlike; height roughly equal to width.

Columnar epithelium

Epithelial cells that are tall and column-shaped.

Pseudostratified epithelium

Epithelium that appears stratified but is actually a single layer, often with cilia.

Keratinized epithelium

Stratified squamous epithelium with superficial dead cells due to keratinization.

Nonkeratinized epithelium

Stratified squamous epithelium with living superficial cells.

Apical surface

The upper free surface exposed to exterior or a body cavity; may have microvilli or cilia.

Basal surface

The lower surface attached to the basement membrane.

Polarity (epithelial)

Epithelial cells have distinct apical and basal surfaces with different structures and functions.

Tight junctions

Occluding junctions that seal cells together to prevent leakage.

Gap junctions

Intercellular channels that allow passage of ions and small molecules for communication.

Desmosome

Anchoring junction that binds cells together to resist tearing.

Hemidesmosome

Junction attaching epithelial cells to the basement membrane.

Basement membrane

Noncellular sheet beneath epithelium, reinforced by basal lamina and reticular lamina; supports and defines the epithelial boundary.

Basal lamina

Part of the basement membrane produced by epithelial cells; glycoprotein and collagen; lies adjacent to basal surface.

Reticular lamina

Deep to basal lamina; network of reticular collagen fibers.

Areolar connective tissue

Loose connective tissue; universal packing material that supports tissues and holds interstitial fluid; inflamed tissue may swell (edema).

Adipose tissue

Connective tissue storing fat; white fat stores energy; brown fat generates heat.

Dense regular connective tissue

Dense collagen fibers aligned in parallel; strong in one direction; found in tendons and ligaments.

Dense irregular connective tissue

Dense collagen fibers arranged irregularly; withstands tension from many directions; found in dermis.

Elastic connective tissue

Connective tissue with many elastic fibers; allows stretch and recoil; found in large arteries.

Hyaline cartilage

Most common cartilage with a glassy matrix; provides support and reduces friction; found at bone ends, rib connections, respiratory passages.

Elastic cartilage

Cartilage with abundant elastic fibers; flexible and resilient; locations include external ear and epiglottis.

Fibrocartilage

Tough cartilage with little ground substance and dense collagen; resists compression; found in intervertebral discs and knee.

Bone (osseous tissue)

Osseous tissue that supports and protects; stores fat; produces blood cells in marrow; highly vascularized; contains osteoblasts and osteocytes.

Osteoblasts

Bone-forming cells that secrete the bone matrix.

Osteocytes

Mature bone cells that maintain bone matrix.

Osteons

Structural units of compact bone.

Blood tissue

Fluid connective tissue that transports gases, nutrients, and wastes; contains erythrocytes, leukocytes, and platelets.

Neuron

Nerve cell that generates and conducts nerve impulses.

Neuroglia

Supporting cells that support, insulate, and protect neurons.

Inflammation

Initial tissue repair response involving chemical signals, vasodilation, increased permeability, and clotting.

Ground substance

Unstructured material filling the space between cells; supports diffusion; contains interstitial fluid, adhesion proteins, and proteoglycans.

Collagen fibers

Strongest and most abundant fibers; provide high tensile strength.

Elastic fibers

Fibers that stretch and recoil; provide elasticity.

Reticular fibers

Fine, branching collagenous fibers forming supportive networks.

Mesenchyme

Embryonic connective tissue from which connective tissues arise.

Extracellular matrix

Nonliving material surrounding cells in connective tissue; composed of ground substance and fibers; enables tissue support.

Endocrine glands

Glands that secrete hormones directly into the bloodstream (ductless).

Exocrine glands

Glands that release secretions onto surfaces or into ducts (saliva, mucous, sweat, oil, etc.).

Goblet cells

Unicellular exocrine glands that secrete mucin to form mucus.

Multicellular exocrine glands

Glands with a duct and a secretory unit; can be simple or compound and tubular or alveolar.

Merocrine secretion

Mode of secretion where products are released by exocytosis as they are produced.

Holocrine secretion

Mode of secretion where the secretory cells rupture to release products.

Apocrine secretion

Mode of secretion where apical portions of the cell pinch off; debated in humans.

Skeletal muscle

Voluntary, striated muscle attached to bones.

Cardiac muscle

Involuntary, striated muscle of the heart; contains intercalated discs.

Smooth muscle

Involuntary, nonstriated muscle found in walls of hollow organs.

Nervous tissue (revisited)

Tissue that conducts electrical impulses; comprises neurons and neuroglia.

Tissue repair

Process to restore tissue integrity after injury, involving inflammation, organization, and regeneration or fibrosis.

Regeneration (tissue repair)

Replacement of destroyed tissue with the same kind of tissue, restoring function."