AP BIOLOGY

Detailed explanation-1: -Here, a soluble signaling molecule secreted by one cell diffuses to another cell in the local neighborhood. For instance, neurotransmitters secreted by neurons diffuse a few nanometers before binding to receptors on target neurons or muscle cells.

Detailed explanation-2: -One unique example of paracrine signaling is synaptic signaling, in which nerve cells transmit signals. This process is named for the synapse, the junction between two nerve cells where signal transmission occurs.

Detailed explanation-3: -The simple gas nitric oxide (NO) is a major paracrine signaling molecule in the nervous, immune, and circulatory systems. Like the steroid hormones, NO is able to diffuse directly across the plasma membrane of its target cells.

Detailed explanation-4: -Examples. Growth factor and clotting factors are paracrine signaling agents. The local action of growth factor signaling plays an especially important role in the development of tissues.

Detailed explanation-5: -Specificity of signaling can be controlled if only some cells can respond to a particular hormone. Endocrine signaling involves the release of hormones by internal glands of an organism directly into the circulatory system, regulating distant target organs.