4.6: Terms and Definitions

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Adipocytes

lipid storage cells

Adipose tissue

specialized areolar tissue rich in stored fat

Anchoring junction

mechanically attaches adjacent cells to each other or to the basement membrane

Apical

that part of a cell or tissue which, in general, faces an open space

Apocrine secretion

release of a substance along with the apical portion of the cell

Apoptosis

programmed cell death

Areolar tissue

(also, loose connective tissue) a type of connective tissue proper that shows little specialization with cells dispersed in the matrix

Astrocyte

star-shaped cell in the central nervous system that regulates ions and uptake and/or breakdown of some neurotransmitters and contributes to the formation of the blood-brain barrier

Atrophy

loss of mass and function

Basal lamina

thin extracellular layer that lies underneath epithelial cells and separates them from other tissues

Basement membrane

in epithelial tissue, a thin layer of fibrous material that anchors the epithelial tissue to the underlying connective tissue; made up of the basal lamina and reticular lamina

Cardiac muscle

heart muscle, under involuntary control, composed of striated cells that attach to form fibers, each cell contains a single nucleus, contracts autonomously

Cell junction

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

Chondrocytes

cells of the cartilage

Clotting

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

Collagen fiber

flexible fibrous proteins that give connective tissue tensile strength

Connective tissue

type of 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

Connective tissue proper

connective tissue containing a viscous matrix, fibers, and cells.

Cutaneous membrane

skin; epithelial tissue made up of a stratified squamous epithelial cells that cover the outside of the body

Dense connective tissue

connective tissue proper that contains many fibers that provide both elasticity and protection

Ectoderm

outermost embryonic germ layer from which the epidermis and the nervous tissue derive

Elastic cartilage

type of cartilage, with elastin as the major protein, characterized by rigid support as well as elasticity

Elastic fiber

fibrous protein within connective tissue that contains a high percentage of the protein elastin that allows the fibers to stretch and return to original size

Endocrine gland

groups of cells that release chemical signals into the intercellular fluid to be picked up and transported to their target organs by blood

Endoderm

innermost embryonic germ layer from which most of the digestive system and lower respiratory system derive

Endothelium

tissue that lines vessels of the lymphatic and cardiovascular system, made up of a simple squamous epithelium

Epithelial membrane

epithelium attached to a layer of connective tissue

Epithelial tissue

type of tissue that serves primarily as a covering or lining of body parts, protecting the body; it also functions in absorption, transport, and secretion

Exocrine gland

group of epithelial cells that secrete substances through ducts that open to the skin or to internal body surfaces that lead to the exterior of the body

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

Gap junction

allows cytoplasmic communications to occur between cells

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 that 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

Inflammation

response of tissue to injury

Lacunae

(singular = lacuna) small spaces in bone or cartilage tissue that cells occupy

Lamina propria

areolar connective tissue underlying a mucous membrane

Loose connective tissue

(also, areolar tissue) type of connective tissue proper that shows little specialization with cells dispersed in the matrix

Mmatrix

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

type of tissue that is 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

type of tissue that is 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, in contrast with the supportive or connective tissue of a gland or organ

Primary union

condition of a wound where the wound edges are close enough to be brought together and fastened if necessary, 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 of certain glands 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, such as lymphatic tissue, spleen, and the liver

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

type of 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 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; each cell is a fiber

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