CLINICAL MEDICINE

Detailed explanation-1: -Hormones are chemical messengers secreted into blood or extracellular fluid by one cell that affect the functioning of other cells.

Detailed explanation-2: -The correct answer: A paracrine signal is a chemical that acts on cells in the immediate vicinity of the cell that secreted the signal. Paracrine signaling is based on the action of specific hormones that are present in close vicinity.

Detailed explanation-3: -An autocrine signal is one that binds to receptors on the surface of the cell that produces it. Juxtacrine signaling involves contact between cells, in which a ligand on one cell surface binds to a receptor on the other.

Detailed explanation-4: -In biology, juxtacrine signalling (or contact-dependent signalling) is a type of cell–cell or cell–extracellular matrix signalling in multicellular organisms that requires close contact.