BIO 111 Lecture Notes - Lecture 6: Nervous Tissue, Histology, Mitosis
Document Summary
Groups of cells similar in structure that perform common or related function. Four basic tissue types: epithelial, connective, muscle, and nervous tissue. Upper free side, is exposed to surface or cavity: most apical surfaces are smooth, but some have specialized fingerlike projections called microvilli. Basal surface, lower attached side, faces inwards toward body: attaches to basal lamina, an adhesive sheet that holds basal surface of epithelial cells to underlying cells. Both surfaces differ in structure and function. No blood vessels are found in epithelial tissue: must be nourished by diffusion from underlying connective tissues. First name indicates number of cell layers: simple epithelia are a single layer thick, stratified epithelia are two or more layers thick and involved in protection (example: skin) Second name indicates shape of cells: squamous: flattened and scale-like, cuboidal: box-like, cube, columnar: tall, column-like. In stratified epithelia, shape can vary in each layer, so cell is named per the shape in apical layercells.
