Tissues

Tissue Basics What is a tissue? Groups of cells working together to perform a function Four Basic Types of Tissues Epithelial Covers surfaces, lines cavities, forms glands Connective Protect/support, stores energy, provides immunity Muscle Causes movement Nervous Detects changes, sends/receives impulses

Epithelial Tissue Characteristics Arranged in closely packed sheets Singular or multiple layers Layered Apical surface (most superficial) Exposed to outer most layer of body cavities Lines organs or exterior of body Lateral surface (cells facing cells) Basal Layer (deepest layer of cells) Basement membrane fibers that bind and support Avascular: Lacking blood vessels Materials are exchanged by diffusion from connective tissue Contain a nerve supply High capacity for renewal

Epithelial Tissue Called: Epithelium = singular, Epithelia = plural Two Types: Covering and Lining Outer covering of the skin and internal organs Lines body cavities and interiors of some systems, blood vessels Glandular Makes up the secreting portions of glands Ex: Sweat glands

Basic Epithelia Shapes Categorized as either: Simple cells organized in a SINGLE layer Found where diffusion, osmosis, filtration, secretion, and absorption occur Stratified cells organized in 2 or more layers Found where protection is needed and there is often wear and tear