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.
C) release their secretions directly into body fluids such as blood. 3. 3) ________ are chemical messengers that are released by cells and transported in the bloodstream to alter the activities of specific cells in other tissues. 1  A) Hormones.  B) Neuropeptides.