What is the function of autocrines?

• A. Signal neighboring cells
• B. Signal the same cell that released them
• C. Transport molecules across membranes
• D. Facilitate long-distance communication

Answer: (B)

Autocrines are signaling molecules that are released by a cell and act on the same cell that secreted them. This form of signaling allows for self-regulation and can modulate the cell's own activities, influencing processes such as growth, differentiation, and immune responses. For example, when immune cells secrete autocrine signals, they can stimulate their own proliferation and activation in response to an infection. This local form of communication is crucial for maintaining homeostasis and coordinating responses within tissues.

The other options describe different types of signaling. Signaling neighboring cells refers to paracrine signaling, which allows cells to communicate over short distances. Transporting molecules across membranes typically involves mechanisms like diffusion or active transport, rather than chemical signaling. Long-distance communication is primarily accomplished through hormones in the endocrine system, which travel through the bloodstream to target distant organs or tissues.