1. Composed of sheets of closely packed cells cells are often strongly connected via tight junctions and desmosomes Tight junctions are common in lining of the stomach & intestines. Why? Desmosomes are common in the epidermis. Why?
Look at the cartoon below (it represents the epithelium that lines much of your respiratory tract). Do you see much space between these cells? Now look at the actual slide and notice the same thing.
2. Has polar sides Apical Surface Apical Surface – side open to exterior or body cavity Basal surface Basal surface – rests on a basement membrane of connective tissue
3. Avascular 3. Avascular – no blood vessels Depends on diffusion of nutrients from underlying tissues 4. Has the capacity to regenerate
1. number 1. number of cell layers Simple Simple – 1 layer Stratified Stratified – more than 1 layer 2. shape 2. shape of cells in the apical layer Squamous Squamous – flat, scale-like Cuboidal Cuboidal – cube-like Columnar Columnar – column-like
Locations Alveoli – air sacs of lungs Kidney Endothelium – lining of heart and blood vesselsFunctions Rapid diffusion Filtration In peneumonia, a build-up of mucous can increase the distance that the gases move. Why does this make it “harder to breathe?”
Locations Sweat gland ducts Ovarian follicle – cells surrounding egg Functions Secretion Sweat Ovarian hormones To the left, we have an oocyte (egg cell) surrounded by stratified cuboidal epithelium. The oocyte is circled in blue
Locations Rare Large ducts of sweat and salivary glands Functions Structure
Locations Respiratory tract from nasal cavity to bronchi Ciliated Goblet cellsFunctions Mucous traps dust & bacteria Cilia sweep debris away from lungs