What are ligands used for in indirect intercellular communication?

• A. As physical connectors between cells
• B. As chemical messengers
• C. As electrical signals
• D. As structural components of cells

Answer: (B)

Ligands serve a crucial role in indirect intercellular communication by acting as chemical messengers. These molecules bind to specific receptors on the surface of target cells, triggering a response that facilitates the communication of information between the cells. This process is fundamental for coordinating various physiological functions, including hormonal signaling, immune responses, and neuronal communication.

The function of ligands as chemical messengers can involve different types of signaling pathways, such as autocrine, paracrine, and endocrine signaling. In autocrine signaling, a cell secretes a ligand that binds to receptors on its own surface, whereas in paracrine signaling, the ligand affects nearby cells. In endocrine signaling, ligands (often hormones) are released into the bloodstream and have effects on distant target cells.

In comparison, the other options each represent different aspects of cellular function or communication that are not linked to the specific role of ligands in signaling processes. For example, physical connectors refer to structures like gap junctions or desmosomes, while electrical signals pertain to the propagation of action potentials in neurons. Similarly, structural components play a role in maintaining cell shape and organization but do not involve the intercellular communication conveyed by ligands.