Chapter 4 - The Tissue Level of Organization - Key Terms

Adipocytes

Lipid storage cells found in adipose tissue.

Adipose Tissue

Specialized areolar tissue rich in stored fat.

Apical

The part of a cell or tissue that faces an open space.

Apocrine Secretion

Release of a substance along with the apical portion of the cell.

Apoptosis

Programmed cell death.

Astrocyte

Star-shaped cell in the central nervous system that regulates ions and contributes to the blood-brain barrier.

Atrophy

Loss of mass and function of tissue.

Basal Lamina

Thin extracellular layer that lies underneath epithelial cells.

Cardiac Muscle

Heart muscle under involuntary control.

Cell Junction

Point of cell-to-cell contact that connects one cell to another in a tissue.

Chondrocytes

Cells of the cartilage.

Clotting

Complex process by which blood components form a plug to stop bleeding; also called coagulation.

Collagen Fiber

Flexible fibrous proteins that give connective tissue tensile strength.

Connective Tissue

Tissue that serves to hold in place, connect, and integrate the body’s organs and systems.

Connective Tissue Membrane

Connective tissue that encapsulates organs and lines movable joints.

Cutaneous Membrane

Skin; epithelial tissue made up of stratified squamous epithelial cells that cover the outside of the body.

Ectoderm

Outermost embryonic germ layer from which the epidermis and nervous tissue derive.

Elastic Cartilage

Type of cartilage with elastin as the major protein; characterized by rigid support and elasticity.

Endocrine Gland

Groups of cells that release chemical signals into the intercellular fluid to be transported to their target organs by blood.

Endoderm

Innermost embryonic germ layer from which most of the digestive and lower respiratory systems derive.

Endothelium

Tissue that lines vessels of the lymphatic and cardiovascular system, made up of simple squamous epithelium.

Epithelial Membrane

Epithelium attached to a layer of connective tissue.

Epithelial Tissue

Tissue that serves primarily as a covering or lining of body parts; functions in protection, absorption, transport, and secretion.

Exocrine Gland

Group of epithelial cells that secrete substances through ducts that open to the skin or internal body surfaces.

Fibroblast

Most abundant cell type in connective tissue; secretes protein fibers and matrix into the extracellular space.

Fibrocartilage

Tough form of cartilage, made of thick bundles of collagen fibers embedded in chondroitin sulfate ground substance.

Fibrocyte

Less active form of fibroblast.

Fluid Connective Tissue

Specialized cells that circulate in a watery fluid containing salts, nutrients, and dissolved proteins.

Goblet Cell

Unicellular gland found in columnar epithelium that secretes mucous.

Ground Substance

Fluid or semi-fluid portion of the matrix.

Histamine

Chemical compound released by mast cells in response to injury; causes vasodilation and endothelium permeability.

Histology

Microscopic study of tissue architecture, organization, and function.

Holocrine Secretion

Release of a substance caused by the rupture of a gland cell, which becomes part of the secretion.

Hyaline Cartilage

Most common type of cartilage; smooth and made of short collagen fibers embedded in a chondroitin sulfate ground substance.

Lacunae

Small spaces in bone or cartilage tissue that cells occupy.

Lamina Propria

Areolar connective tissue underlying a mucous membrane.

Matrix

Extracellular material which is produced by the cells embedded in it, containing ground substance and fibers.

Merocrine Secretion

Release of a substance from a gland via exocytosis.

Mesenchymal Cell

Adult stem cell from which most connective tissue cells are derived.

Mesenchyme

Embryonic tissue from which connective tissue cells derive.

Mesoderm

Middle embryonic germ layer from which connective tissue, muscle tissue, and some epithelial tissue derive.

Mesothelium

Simple squamous epithelial tissue which covers the major body cavities and is the epithelial portion of serous membranes.

Mucous Connective Tissue

Specialized loose connective tissue present in the umbilical cord.

Mucous Gland

Group of cells that secrete mucous, a thick, slippery substance that keeps tissues moist and acts as a lubricant.

Mucous Membrane

Tissue membrane that is covered by protective mucous and lines tissue exposed to the outside environment.

Muscle Tissue

Tissue capable of contracting and generating tension in response to stimulation; produces movement.

Myelin

Layer of lipid inside some neuroglial cells that wraps around the axons of some neurons.

Myocyte

Muscle cells.

Necrosis

Accidental death of cells and tissues.

Nervous Tissue

Tissue capable of sending and receiving impulses through electrochemical signals.

Neuroglia

Supportive neural cells.

Neuron

Excitable neural cell that transfer nerve impulses.

Oligodendrocyte

Neuroglial cell that produces myelin in the brain.

Parenchyma

Functional cells of a gland or organ.

Primary Union

Condition of a wound where the wound edges are close enough to be brought together, allowing quicker and more thorough healing.

Pseudostratified Columnar Epithelium

Tissue that consists of a single layer of irregularly shaped and sized cells that give the appearance of multiple layers; found in ducts and the upper respiratory tract.

Reticular Fiber

Fine fibrous protein, made of collagen subunits, which cross-link to form supporting “nets” within connective tissue.

Reticular Lamina

Matrix containing collagen and elastin secreted by connective tissue; a component of the basement membrane.

Reticular Tissue

Type of loose connective tissue that provides a supportive framework to soft organs.

Schwann Cell

Neuroglial cell that produces myelin in the peripheral nervous system.

Secondary Union

Wound healing facilitated by wound contraction.

Serous Gland

Group of cells within the serous membrane that secrete a lubricating substance onto the surface.

Serous Membrane

Tissue membrane that lines body cavities and lubricates them with serous fluid.

Simple Columnar Epithelium

Tissue that consists of a single layer of column-like cells; promotes secretion and absorption in tissues and organs.

Simple Cuboidal Epithelium

Tissue that consists of a single layer of cube-shaped cells; promotes secretion and absorption in ducts and tubules.

Simple Squamous Epithelium

Tissue that consists of a single layer of flat scale-like cells; promotes diffusion and filtration across the surface.

Skeletal Muscle

Usually attached to bone, under voluntary control, each cell is a fiber that is multinucleated and striated.

Smooth Muscle

Under involuntary control, moves internal organs, cells contain a single nucleus, are spindle-shaped, and do not appear striated.

Stratified Columnar Epithelium

Tissue that consists of two or more layers of column-like cells, contains glands and is found in some ducts.

Stratified Cuboidal Epithelium

Tissue that consists of two or more layers of cube-shaped cells, found in some ducts.

Stratified Squamous Epithelium

Tissue that consists of multiple layers of cells with the most apical being flat scale-like cells; protects surfaces from abrasion.

Striation

Alignment of parallel actin and myosin filaments which form a banded pattern.

Supportive Connective Tissue

Type of connective tissue that provides strength to the body and protects soft tissue.

Synovial Membrane

Connective tissue membrane that lines the cavities of freely movable joints, producing synovial fluid for lubrication.

Tight Junction

Forms an impermeable barrier between cells.

Tissue

Group of cells that are similar in form and perform related functions.

Tissue Membrane

Thin layer or sheet of cells that covers the outside of the body, organs, and internal cavities.

Totipotent

Embryonic cells that have the ability to differentiate into any type of cell and organ in the body.

Transitional Epithelium

Form of stratified epithelium found in the urinary tract, characterized by an apical layer of cells that change shape in response to the presence of urine.

Vasodilation

Widening of blood vessels.

Wound Contraction

Process whereby the borders of a wound are physically drawn together.