Tissue Types: Structure and Function

Flashcards covering the structure, functions, and key features of epithelial, connective, muscle, and nervous tissues, as well as specialized cells and extracellular components.

Epithelial tissues

Wrappers and liners of the body's organs; they are avascular.

Avascular

Lacking blood vessels, relying on diffusion from nearby connective tissue for oxygen and nutrients.

Lumen

The clear empty space in a hollow organ or a free space at the edge of a tissue section, typically faced by the apical surface of epithelial tissue.

Apical surface

The side of an epithelial sheet facing the lumen or external space.

Basal surface

The side of an epithelial sheet attached to the connective tissue, deep to the epithelium.

Basement membrane

A thin layer of extracellular proteins beneath the basal surface that helps the epithelium attach to connective tissue.

Keratin

A thick apical layer of protein produced by some epithelia, providing a tough, protective outer surface.

Goblet cells

Specialized cells within some epithelial subtypes that produce mucus to protect and lubricate luminal surfaces.

Connective tissues

Tissues designed to connect, support, and cushion other tissues; always located deep to epithelial tissues and contain blood vessels.

Ground substance

A somewhat clear, thick material that fills the extracellular space in connective tissues and contains fibers, providing a medium for diffusion.

Collagen fibers

Thick, long, unbranched, unstretchy fibers resembling stiff ropes found in connective tissue, providing strength.

Elastic fibers

Thinner, branching, stretchy fibers that rejoin to form a network, giving connective tissue elasticity.

Reticular fibers

The thinnest, angular/branched (net-like) fibers in connective tissue, strong but flexible, forming supportive nets.

Connective tissues proper

A category of connective tissues characterized by fibers within ground substance; includes areolar, adipose, and reticular connective tissue.

Dense connective tissues

A category of connective tissues with more fibers and less ground substance; includes dense regular, dense irregular, and elastic connective tissue.

Supporting connective tissues

Dense and strong connective tissues, including cartilage and bone.

Fluid connective tissues

Connective tissues composed of fluids, such as blood and lymph.

Adipocytes

Specialized cells found in adipose tissue that store triglycerides.

Chondrocytes

Cells in cartilage that synthesize the extracellular matrix and become trapped in spaces called lacunae.

Osteocytes

Cells in bone that synthesize the extracellular matrix and become trapped in spaces called lacunae.

Lacunae

Small spaces within the extracellular matrix of cartilage and bone that house chondrocytes and osteocytes.

Erythrocytes (RBCs)

Red blood cells, located in blood, responsible for carrying oxygen.

Leukocytes (WBCs)

White blood cells, located in blood, performing immune functions.

Muscle tissue

Contractile tissue that shortens when stimulated to move the skeleton or soft tissue of organs.

Skeletal muscle

Muscle tissue under voluntary control, with very large cells, multiple nuclei, and visible striations.

Cardiac muscle

Muscle tissue found in the walls of the heart, responsible for pumping blood; cells are short, branched, have striations, and contain intercalated disks.

Smooth muscle

Muscle tissue under involuntary control, with long, tapered (fusiform) cells, a central nucleus, and no visible striations.

Intercalated disks

Specialized cell junctions found in cardiac muscle that tightly connect cardiac cells to prevent separation during contraction.

Striations

Visible banded patterns in muscle tissue caused by the organized arrangement of contractile proteins, present in skeletal and cardiac muscle.

Fusiform

A shape describing smooth muscle cells, which are long and tapered at both ends.

Nervous tissue

Tissue specialized to send messages, consisting of cells with long processes that extend to connect with neighbors.