Unit 3: Microscopes and Tissues Vocabulary

Vocabulary flashcards defining the major tissues (epithelial, connective, muscle, nervous) and microscopy terminology for Unit 3 (HAP Chapter 4).

Simple squamous epithelium

An epithelial tissue consisting of a single layer of flattened, scale-like cells.

Simple cuboidal epithelium

An epithelial tissue composed of a single layer of cube-shaped cells.

Simple columnar epithelium

An epithelial tissue consisting of a single layer of tall, column-shaped cells.

Pseudostratified columnar epithelium

A single layer of columnar epithelial cells of varying heights whose nuclei appear at different levels, giving the false impression of multiple layers.

Stratified squamous epithelium

A thick epithelial tissue composed of multiple cell layers, with flattened squamous cells at the apical surface.

Transitional epithelium

A specialized stratified epithelium whose cells can change shape and stretch, commonly lining organs of the urinary system.

Simple epithelium

Epithelial tissue composed of only a single layer of cells.

Stratified epithelium

Epithelial tissue composed of two or more layers of cells.

Apical surface

The unattached, free, or exposed upper surface of an epithelial tissue facing an open space or lumen.

Basement membrane

A thin, acellular layer that anchors epithelial cells to underlying connective tissue.

Goblet cells

Individual mucus-producing epithelial cells scattered among columnar epithelial cells.

Endocrine glands

Ductless glands that secrete chemical messengers (hormones) directly into the blood or extracellular fluid.

Exocrine glands

Glands that secrete their products into ducts that lead onto body surfaces or into body cavities.

Areolar tissue

A loose connective tissue containing a soft, gel-like matrix that cushions and wraps body organs.

Adipose tissue

A loose connective tissue primarily composed of adipocytes specialized for fat storage and insulation.

Reticular tissue

A network of reticular fibers and cells that forms the internal supporting framework (stroma) of lymphoid organs.

Dense regular connective tissue

A connective tissue featuring closely packed, parallel collagen fibers that provides strong resistance to pulling forces in one direction, such as in tendons and ligaments.

Dense irregular connective tissue

A connective tissue containing randomly arranged, interwoven bundles of collagen fibers that withstand tension exerted in multiple directions.

Hyaline cartilage

The most common type of cartilage, having a smooth, glassy matrix with hidden collagen fibers, found at the ends of long bones, ribs, and the nose.

Elastic cartilage

A flexible cartilage containing abundant elastic fibers that maintains shape while allowing great flexibility, such as in the external ear.

Fibrocartilage

A highly compressible cartilage containing thick rows of collagen fibers, capable of absorbing shock in intervertebral discs and knee menisci.

Extracellular matrix

The nonliving material secreted by connective tissue cells, consisting of ground substance and protein fibers.

Collagen fibers

Tough, flexible protein fibers in the extracellular matrix that provide high tensile strength.

Elastic fibers

Protein fibers made of elastin that allow tissues to stretch and recoil.

Reticular fibers

Fine, branching collagenous fibers that form delicate supporting networks in tissues.

Fibroblasts

Large, flat connective tissue cells that produce fibers and ground substance of the extracellular matrix.

Chondrocytes

Mature cartilage cells found within small matrix cavities called lacunae.

Osteocytes

Mature bone cells located inside lacunae within calcified bone matrix.

Macrophages

Phagocytic cells derived from monocytes that engulf bacteria, foreign particles, and dead cell debris.

Edema

Abnormal accumulation of excess fluid in interstitial spaces, leading to tissue swelling.

Leukocytes

White blood cells that protect the body against infection and foreign invaders.

Erythrocytes

Red blood cells specialized to transport oxygen throughout the bloodstream.

Skeletal muscle

Voluntary, striated muscle tissue consisting of long, multinucleated, cylindrical fibers attached to the skeleton.

Cardiac muscle

Involuntary, striated muscle tissue found exclusively in the heart wall, possessing branching cells with intercalated disks.

Smooth muscle

Involuntary, non-striated muscle tissue made of spindle-shaped, uninucleated cells found in the walls of hollow organs.

Intercalated disks

Specialized gap-junction-containing cell junctions between cardiac muscle cells that allow rapid electrical communication.

Striations

Visible alternating light and dark transverse bands across skeletal and cardiac muscle fibers.

Neurons

Excitable nerve cells specialized to receive stimuli and transmit electrical impulses.

Neuroglia

Non-conducting supportive cells of nervous tissue that protect, nourish, and insulate neurons.

Axons

Neuronal processes that conduct electrical impulses away from the cell body.

Dendrites

Branching extensions of a neuron that receive signals from other cells and convey them toward the cell body.

Coarse adjustment knob

The microscope control used for rapid, large-scale focusing by noticeably moving the stage or objective lens.

Fine adjustment knob

The microscope control used for precise, small-scale focusing to sharpen specimen details under high power.

Diaphragm (Microscope)

An adjustable shutter or rotating disc beneath the stage that controls the amount of light reaching the specimen.

Oil immersion lens

A high-power microscope objective (typically $100\times$) requiring immersion oil between the lens and slide to improve resolution.