Histology

Groups of closely related associated cells that are similar in structure and perform a common function are tissue. Cytology – the study of cells Histology – the study of tissue

Components of Tissues Cells Extracellular matrix may be fluid or protein fibers Matrix Cell

4 Basic Types of Tissue in Humans Epithelial tissue Connective tissue 3. Muscle tissue 4. Nervous tissue

Epithelial Tissue

Found: 1. coverings and linings – body surfaces, lines open cavities (digestive and respiratory), lines blood vessels and heart, walls of organs in ventral cavity 2. Glandular - endocrine and exocrine

Function: Protection Absorption Filtration Secretion Take in substances Filtration Secretion Release substances

Characteristics: cellularity- mostly cells, little matrix fit close together (tight junctions and desmosomes) free surfaces

Characteristics: cellularity- mostly cells, little matrix Avascular - nourishment by diffusion from underlying tissue free surfaces fit close together (tight junctions and desmosomes) rests on a basement membrane - which reinforces - separates epithelial from connective regeneration

How to identify? identified by cell shape and number of cell layers * all are many sided in cross section

3 Common Types Based on Cell Height Squamous - flat Cuboidal - square Columnar – column shaped ***nuclear shape the same

2 Based on Cell Arrangement (layer) Simple - only one cell layer Stratified - layers are stacked

Pseudostratified Ciliated Columnar Epithelial Free Surface Cilia False layers Basement Membrane

How to Properly Label Epithelial Tissue Free Surface This is a cell. Cell Membrane Nucleus Basement Membrane Connective Tissue