Unit 2 Cells and Tissues Levels of Organization

Unit 2 - Cells and Tissues

Levels of Organization • Cells – Building blocks of the body • Tissues – A group of similar cells that combine to perform a certain function (4 - muscle, • nervous, connective, epithelial) • Organs – Two or more different types of tissue – combined to perform a certain • function – (kidney, liver, lung) • System – organization of > 2 or more organs perform a more general function

Histology-study of tissues • • • 4 types of tissue in the body epithelial connective muscular nervous

Epithelial Tissue Arrangements: • Simple- Cells are found in a single layer attached to the basement membrane • Stratified- Cells are found in 2 or more layers stacked atop each other • Pseudostratified- a single layer of cells that appears to be multiple layers due to variance in height and location of the nuclei in the cells.

Pseudo stratified

Epithelial Tissue Shapes: • Squamous- (Latin, squama- scale)- flat, thin, scale-like cells • Cuboidal- cells that have a basic cube shape. Typically the cell's height and width are about equal. • Columnar- tall, rectangular or column-shaped cells. Typically taller than they are wide.

Epithelial characteristics: • • major tissue of glands inner lining of body cavities inner lining of hollow organs anchored to connective tissue by a basement membrane • lacks blood vessels

Connective Tissue functions: • • • Binds structures Provides support Protection Stores fat Produces blood cells

Connective Tissue characteristics: • Cells farther apart • Intercellular material/matrix between them • FIBROBLAST- major cell creates fibers

Muscular Tissue * MOVEMENT of structures or materials 3 Types: • SKELETAL/STRIATED • SMOOTH • CARDIAC

NERVOUS TISSUE • Transmit electrical impulses throughout the body • Includes- brain, spinal cord, nerves • Neurons- basic unit of nervous system, TRANSMIT impulses • Neuro. GLIA- supporting cells, no impulses