a & p chapter 4 - tissues

tissue

a group of similar cells plus extracellular material working together

four primary tissue types

epithelial tissue, connective tissue, muscle tissue, and nervous tissue

ectoderm

forms epidermis and much of the nervous system and epithelial outer layer

mesoderm

forms muscle and connective tissues (blood, bone, cartilage, and many membranes)

endoderm

forms much of the epithelial lining of the digestive and respiratory tracts

epithelial tissue

tissue made of tightly packed cells with little extracellular matrix.

protects (covers surfaces), absorbs (lines cavities), and secretion (forms glands).

replaces damaged cells quickly, especially in high-wear areas.

connective tissue

supports, protects, stores energy, and transports materials

muscle tissue

contracts to produce movement or pressure

nervous tissue

signaling, detects change and rapidly coordinates responses

epithelial membranes

combine epithelium tissue with underlying connective tissue

mucous membranes

line tracts open to the exterior (type of epithelial membrane)

serous membranes

line closed body cavities and reduce friction (type of epithelial membrane)

synovial membranes

joints and lubrication; line joint cavities and produce synovial fluid (connective tissue membrane)

apical surface

free/top surface of epithelial tissue that faces a space, lumen, or outside environment

often specializes in absorption, secretion, or movement

basal surface

bottom surface of epithelial tissue that attaches to the basement membrane and connective tissue, helping anchor the epithelium

epithelial polarity

the apical and basal sides have different functions, allowing materials to move through the epithelial layer in a controlled direction

cell junctions

connections between cells that help seal, anchor, or communicate with neighboring cells

tight junctions

form seals between neighboring cells that limit leakage and help keep substances in separate compartments

anchoring junctions

strong connections that help cells resist pulling, stretching, and tearing

gap junctions

form channels between neighboring cells that allow ions and small molecules to pass directly from cell to cell for rapid communication

simple epithelium (layer)

epithelium with one cell layer, mainly used for absorption, secretion, filtration, and exchange

stratified epithelium (layer)

epithelium with multiple cell layers, mainly used for protection

pseudostratified epithelium (layer)

epithelium that looks multilayered but is actually one layer because every cell contacts the basement membrane

transitional epithelium (layer)

epithelium that stretches and changes shape without tearing especially in the urinary system

squamous cells (shape)

thin, flat cells that allow fast diffusion and filtration

cuboidal cells (shape)

cute-shaped cells specialized mainly for secretion and absorption

columnar cells

tall cells specialized mainly for absorption and secretion

simple squamous epithelium (specific tissue)

one layer of thin, flat cells for fast diffusion and filtration. found in alveoli, capillaries, and serous membranes

simple squamous