List the mechanisms by which intercellular chemical signals produce responses in their target tissues.

Describe three ways in which a gradual increase inan extracellular signal can be sharpened by the target cellto produce an abrupt or nearly all-or-none response.

Why do different cells respond to the same stimulus in different ways? State three potential outcomes of signal transduction events.

The fight-or-flight reaction prepares an animal to Pesponu Lu a threatening situation, by either fighting or running away. One aspect of this response is changes in blood flow such that the skeletal muscles and heart receive higher blood flow (vessels dilate) while digestive organs receive less (vessels constrict). A) Which signal molecule(s) is/are involved in this response, and how do they produce these changes in blood vessels? Briefly explain how this example illustrates how different cells are able to use the same ligands in different ways.