1) during dental procedures, dentists inject local anesthetics into the nerve pathway
supporting the region they are working on. these local anesthetics block nat (sodium)
channels. explain in detail the process of a typical action potential, and how local
anesthetics prevent the transmission of pain impulses to the brain.

In an experiment examining the effects tai chi on arthritis pain, callahan (2010) selected a large sample of individuals with doctor-diagnosed arthritis. half of the participants immediately began a tai chi course and the other half (the control group) waited 8 weeks before beginning. at the end of 8 weeks, the individuals who had experienced tai chi had less arthritis pain that those who had not participated in the course.