When local anesthetics are applied to nervous tissues, they interact with proteins on the surface of the cell that are involved in the flow of electrical ions across the cell membrane. This effect interrupts the conduction of electrical impulses along the nerve fiber so that signals are not transmitted from the body to the brain. Most major nerves in the body contain several different types of nerve fibers, and some of these are more sensitive than others to the effects of local anesthetics. Thus as more and more local anesthetic drug is applied to the nerve, more and more types of sensations are blocked. Temperature and pain are more easily blocked, whereas motor function (the ability to move) is one of the last to go. In addition, nerves vary in their sensitivity to these medications as a result of age and certain diseases such as Diabetes.