A & P 1: exam 2

integumentary system

tissues

a group of cells that work together to perform one or more specialized functions

intracellular

refers to the internal environment of the cells, contained within the cellular membrane

extracellular

the environment outside the cells, or outside the cellular membrane

extracellular membrane

large network of proteins, molecules, and fluid that surrounds and gives structure to cells; cells secrete substances to help regulate their extracellular material and fluids, called an extracellular matrix

histology

microscopic study of the structure of tissues and their surrounding extracellular matrix

epithelial tissue

covers exposed surfaces, lines passageways/cavities, and can produce glandular secretions; serves as a layer of protection; decreases friction and provides lubrication of organs; manage materials in the body by secretion and excretion; cleanses by blocking dust/dirt or particular matter from the openings of the body

connective tissue

supports and underlies other structures and fills the internal space of the body

muscle tissue

contracts to enable movement

nervous tissue

carries electrical impulses and translates information to control activities of the body

5 defining characteristics of epithelial tissue

epithelial cells exhibit polarity; epithelial tissue is avascular; the basal surface of epithelia connects to the basement membrane; epithelium is highly regenerative; epithelial tissue cells are always connected to one another because of specialized cell junctions

epithelial cells exhibit polarity

cells have unique surfaces, each with specialized features: apical, lateral, and basal; apical surface allows the cells to secrete or absorb materials from the lumen

apical surface - epithelial tissue

surface facing the external environment or inside of a lumen (opening); can have specialized modifications allowing for specialized functions; microvilli extend on the apical surface (add extra surface area to cells)

cilia

longer cytoplasmic extensions and have an internal structure that allows for their movement

ciliated epithelial cells

can be found in places such as the trachea and bronchi

epithelial tissue is avascular

meaning these cells do not have a direct blood supply; nutrients must enter, and wastes must leave by diffusion or absorption from underlying tissues because no blood vessels cross the basement membrane; is innervated

the basal surface of epithelia connects to the basement membrane

basement membrane or basal lamina is noncellular and protein rich, allowing for cells to anchor to it for support; the basement membrane separates epithelium from other tissue, it is produced by the basal surface of epithelial cells, as well as connective tissue cells deep to it

Hyaluronan

(hyaluronic acid) is one type of polysaccharide derivative that helps lock epithelial cells together, called intracellular cement

Epithelial tissue cells are always connected to one another because of specialized cell junctions

the lateral surfaces are connected between adjoining cells with specialized intracellular connections with unique proteins

gap junctions

also called communication junctions, are unique cellular structures that permit the free diffusion of ions and small molecules between cells

tight junctions

also called occluding junctions, serve as an impermeable barrier; they do not allow solutes and fluids to diffuse between the cells in these locations; typically located at the most apical point between the adjoining cells; a tight junction is formed when the plasma membrane of 2 outer layers of the cells fuse together; these junctions are what allow epithelial cells to function as a barrier and covering of underlying tissues