Final answer:
In indirect signaling, a chemical called a ligand binds to receptors on a target cell, triggering a response through signal transduction. There are various types of signaling, including paracrine, endocrine, autocrine, and signaling via gap junctions.
Step-by-step explanation:
When indirect signaling is used, the target cell responds to the signal when the chemical, known as a ligand, is released by a signaling cell and subsequently binds to a receptor on the target cell. This binding causes a response in the target cell, initiating a process known as signal transduction. Types of signaling include paracrine signaling, which acts on nearby cells, endocrine signaling, which transports ligands through the circulatory system to distant cells, autocrine signaling, which acts on the signaling cell itself, and direct signaling across gap junctions, which involves signaling molecules moving directly between adjacent cells.