Epithelial Tissue

Functions:

2 Types

Covering and lining: Outer layer of skin and organs, lines blood vessels, and lines body cavities
Glandular: sweat and thryoid glands

General Features

Closely packed cells with little extracellular material
single or multiple layers of cells
has an apical (free) surface and a basal surface which adheres it to the basement membrane
Avascular (without blood vessels): wastes and nutrients are exchanged with connective tissues through diffusion
Adheres to connective tissue: holds epithelium in place
Has nerves supply
High mitotic hates: repairs wear and tear

Covering and Lining Epithelium

Single layer: Simple epithelium
Several layers: Stratified epithelium
1 layer of cells, some don’t reach apical surface, but all cells touch basement membrane: pseudostratified

Cell Shapes

Glandular Epithelium

Gland: 1 cell or a group of cells that produce and discharge substances

2 Main Types:

Exocrine: secretes into ducts that open into internal/external surfaces, secrete mucus, perspiration, oil, wax, digestive enzymes

Endocrine: ductless, products enter extracellular fluid and diffuse them into the blood; secretes hormones

3 Types of exocrine glands