9781422286999

Words to Understand motivation: Your reason for doing something. endurance: The ability to exercise for a long time. tissue: A certain kind of material inside our bodies that do one kind of job. Tissues are made up of just one kind of cell.

contract: Shrink or get smaller. dilate: When something circular gets wider. For example, your pupils and blood vessels dilate when they get bigger. stroke: When a person has a blood clot or is bleeding inside his brain. capacity: The greatest limit of something’s ability to do something. thermostat: Something that controls the temperature.