The Tissue Level of Organization

Key Terms

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
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
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