Chapter 16, Problem 1Q

Summary Introduction

To suggest: The ways in which the action of paracrine signal molecules maintains a local stimulus and thus prevents it from straying too far from their point of origin.

Introduction: In paracrine signaling, the effector molecules do not enter the blood stream unlike the endocrine signaling, rather these molecules disseminate through the extracellular matrix and remain locally in the neighborhood of cells which secreted them and hence they are also known as local mediators. Paracrine signaling is involved in the regulation of inflammation at the site of infection, controlling rapid, progressive cell division in wound healing and in several cell signaling mechanisms involved in embryonic development.

Explanation of Solution

The various ways in which the paracrine effector molecules can be maintained as a local stimulus are given below:

• The effector molecules can have a short half-life period, so they do not have any effect for prolonged time.
• The effector molecules can be degraded using enzymes in the extracellular matrix if they drift away from the point of origin cell.
• The effector molecules can also be made to attach to the extracellular matrix proteins until they bind to their receptor.
• The effector molecules can be taken up rapidly by the neighboring cells in order to initiate the cascade mechanisms.