Tissues a Group of similar cells with common function 4 Major types: – 1.Epithelial (Epith.) – 2.Connective (CT) – 3.Muscle – 4.Nervous

Epithelial Lining, covering, and glands Protects, absorbs, filters, and secretes Cells are tightly packed together Have a “free space” surface (organ exterior or to inside cavity) Rest on a supporting Basement Membrane Lack blood vessels (avascular) and depend on diffusion for food and oxygen

Classified by shape and arrangement Arranged in single layer of cells = simple (absorption) Arranged in many layers of cells = stratified (protection) Cells that are flat = squamous Cells that are cube shape = cuboidal Cells that are elongated = columnar

Simple Squamous Epith. Single layer of flat cells; nuclei are thin Found in air sacs of lungs, walls of tiny blood vessels Good for absorption

Simple Cuboidal Epith. Single layer of cube shaped cells Good for absorption and secretion Found in kidney tubules and glands

Simple Columnar Epith. Single layer of column shaped cells Nuclei located near the base Good for absorption and protection Contain goblet cells – cells that secrete mucus to lubricate free space Found in digestive tract

Pseudostratified Columnar Epith. False impression of layers All cells touch the basement membrane but not all cells reach the free space Can have cilia near free space & goblet cells Good for absorption and secretion Found in respiratory tract

Stratified Squamous Epith. Cells at the free edge are squamous shape Cells near basement membrane are cuboidal or columnar Good for protection Found lining the mouth, throat, and anal cavity; outer portion of the skin

Transitional Epith. Tissue adapted for stretching Lines urinary organs (bladder) Cells at free surface can change shape – If stretched = squamous – If not stretched = cuboidal