ABSTRACT

In general, toxicants exert their effects when they interact with cells. This cellular interaction may occur: (1) on the surface of the cell, (2) within the cell, or (3) in the underlying tissues and extracellular (interstitial) space (Figure 4-1). Although there are four different types of tissues in the human body (epithelial, connective, muscle, and nerve), it is a collection of epithelial cells that forms the epithelium that covers the surface of the body (i.e., skin), and forms the lining of the lumen (or inside walls) of the respiratory and digestive systems.