Tissues

• Tissue


  group of specialized cells and the extracellular substances surrounding them
• Histology


  microscopic study of tissue
• Epithelium


  covers and protects surfaces both outside and inside the body
• Free surface


  Part of epithelial cells which is not in contact with other cells
• Lateral surface


  cells are attached to other epithelial cells
• Basal surface


  surface of an epithelial cell that faces the basement membrane
• Basement membrane


  a specialized type of extracellular material secreted by epithelial and connective tissue cells.
• Simple Epithelium


  single layer of cells
• Stratified Epithelium


  several layers of cells
• Pseudostratified columnar epithelium


  a special type of simple epithelium that consists of a falsely-stratified single layer of epithelial cells resting on a basement membrane.
• Squamous


  cells that are flat or scalelike
• Cuboidal


  cells are as wide as tall, like cubes
• Columnar


  cells are taller than they are wide
• simple squamous epithelium


  single layer of flattened cells
• simple cuboidal epithelium


  single layer of cube shaped cells
• simple columnar epithelium


  single layer of tall cells that fit closely together
• Mucus


  clear, thick fluid that protects the lining of the intestine
• Pseudostratified columnar epithelium


  secretes mucus, which covers its free surface, typically contains cilia
• stratified squamous epithelium


  A thick epithelium, because of the several layers of cells. The deepest cells are actually cuboidal or columnar and are capable of dividing and producing new cells. As the new cells are pushed to the surface, they become flat and thin. The "keratinized" cell of this type covers the skin.
• stratified cuboidal epithelium


  consists of two or three layers of cuboidal cells that typically forms the lining of a lumen of ducts and glands
• stratified columnar epithelium


  consists of several layers of tall epithelial cells and is found in the vas deferens, part of the male urethra, and parts of the pharynx
• Transitional epithelium


  special type of stratified epithelium that can be greatly stretched
• Endothelium


  innermost lining of blood vessels
• Microvilli


  cylindrical extensions of the cell membrane that increase the free surface area
• Cilia


  propel materials along the free surface of the cells
• Desmosomes


  mechanically bind cells together
• Hemidesmosomes


  modified desmosomes and anchor cells to the basement membrane
• Tight junctions


  bind adjacent cells together and form permeability barriers
• Adhesion Belt


  Found just below the tight junction, acts as a weak glue that holds cells together
• Gap Junctions


  small channels that allow small molecules and ions to pass from one epithelial cell to an adjacent one
• Exocrine Glands


  glands with ducts
• Endocrine glands


  glands that are separated from epithelium and have no ducts
• Hormones


  chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues
• Multicellular glands


  glands that consist of many cells mostly are exocrine
• Goblet Cells


  cells that secrete mucus
• Simple Glands


  single unbranched duct
• Compound glands


  multiple branched ducts
• Tubular


  glands with secretory regions shaped as tubules
• Acinar


  glands that shape in saclike structures
• Merocrine Secretion


  product is released from secretory vesicles by exocytosis