Epithelial Tissue and Levels of Organization of Body

Cells

Basic unit of life

Tissue

A group of alike cells

Organ

Multiple tissues working together

Organ System

Group of organs that serve a certain function (ex: Digestive System)

Organism

Individual life form

Carinoma

Cancer Cells

Carcinogen

Something that causes cancer

Benign Tumors

Not cancerous and have abnormal growth also does not move (ex. Mole, cyst)

Malignant

Cancerous, abnormal growth, ad undergoes metastasis (spreads)

Structure of Epithelial Tissue

• Cells are closely Joined Together

• Exposed to air or fluid (ex. Skin)

• Supported by connective tissue

• Nerves in Tissue but do not have blood

Function of Epithelial tissue

• Cover outside of body

• Lines organs and cavities

• Regenerates Quickly

• Barrier against microbes and fluid loss

Shapes of Epithelial

• Squamous (Circle and flat)

• Columnar (Cube shape)

• Cuboidal (Tall and straight, nucleus at the bottom)

Layers of epithelial

• Simple (One layer)

• Stratified (Two or more layers)

• Pseudostratified (One layer w/ the appearance of multiple cell)

Simple Squamos

• Thin Leaky

• Cells exchange materials by diffusion

Stratified Squamous

• Regenerates rapidly at bottom part of tissue

• New cells are pushed up to replace cells exposed at the top (ex. abrasion)

• Bottom cells are tightly packed until they reach top layer

Simple cuboidal

• Specialized for secretions

• Organized in a circular pattern

Stratified Cuboidal

• Rare in the body

• (Ex. gland in breast, glands must be more supported)

Simple Columnar

• Filled with cytoplasm at top

• Absorption

Stratified Columnar

• Rare in body

• Protection

• Secretion(ex. male urethra)

Transitional Epithelium

• Exception

• Several layers

• Bottom cells are cuboidal

• Surface cells are dome shaped

• Strechy ( urinary bladder)

Pseudostratified Columnar

• Exception

• One cell layer but appears to have multiple

• (Ex. Lines nasal passages)