Tips. 1  If you want to focus on a particular muscle area, you can do so by changing the stride length. 2  For an elliptical with multiple users, use one whose stride length is adjustable to accommodate different heights. 3  Do not rely solely on guidelines.
3. Intercellular chemical signals secreted into the circulatory system; carried to organs they control, where they bind to receptors and produce a response. 4. Intercellular chemical signals, secreted by nerve cells; important in the function of the nervous system.
chemical messengers which are released by nerve cells, endocrine organs and immune cells. The immune system is composed of lymphoid tissues, and the fact that these tissues are innervated with sympathetic nerve fibers adds support to the evidence that the central nervous system directly influences immune function.