Epithelial Tissue Characteristics

Vocabulary flashcards covering the key characteristics, structures, and classifications of epithelial tissue.

Cellularity

A characteristic of epithelial tissue describing how it is composed almost entirely of close-packed cells with only a tiny amount of extracellular material lying in the narrow spaces between them.

Specialized contacts

Lateral contacts, including tight junctions and desmosomes, that bind adjacent epithelial cells close together to form continuous sheets.

Polarity

A property of epithelia meaning that cell regions near the upper apical surface differ in structure and function from those near the lower basal surface.

Apical surface

An upper, free surface of an epithelium that is exposed to the body exterior or to the cavity of an internal organ.

Basal surface

The lower attached surface of an epithelium.

Microvilli

Fingerlike extensions of the plasma membrane on apical surfaces that tremendously increase exposed surface area for absorption or secretion.

Brush border

A fuzzy appearance of cell apices created by dense microvilli on epithelial cells that absorb or secrete substances.

Cilia

Motile extensions on the free surface of certain epithelia, such as those lining the trachea, that propel substances along the surface.

Basal lamina

A thin, noncellular supporting sheet lying adjacent to the basal surface that consists largely of glycoproteins secreted by epithelial cells and acts as a selective filter.

Avascular but innervated

A characteristic of epithelial tissue indicating that it contains no blood vessels but is supplied by nerve fibers.

Regeneration

The high capacity of epithelial tissue to replace lost or damaged cells rapidly by cell division when supplied with adequate nutrition.

Simple epithelia

Epithelia composed of a single cell layer, typically found where absorption, secretion, and filtration occur.

Stratified epithelia

Epithelia consisting of two or more cell layers stacked on top of one another, common in high-abrasion areas where protection is important.

supported by connective tissue

Reticular limina contains network of collagen protein fibers that belongs to connective tissue. 2 laminar form the basement membrane

Basement membrane

Reinforces epithelial sheet and helps resist tearing

What is the 2 layers that the basement membrane is made up of?

Basal lamia and reticular lamina

Avascular but innervated

Epithelium is avascular. Epithelium cells nourish from substances diffusing from blood vessels

What does avascular mean

No blood vessels

What does innervated mean

Has nerves

Regeneration

Epithelium has high regenerative capacity. When surface cells get hurt quickly as long as they have good nutrition they replace quickly by cell diffusion. (Mitosis)

Where do the cells get nutrients from to regenerate?

The nutrients diffuses from the blood vessel to the connective tissue

How does cell division happen

Mitosis

Study of tissues is

Histology

4 main types of tissues

Nervous tissue, muscle tissue, epithelial tissue, connective tissue