Most hormones in the human body are peptides, which act as signaling molecules by binding to specific cell-surface receptors to regulate physiological processes.

Peptides are short chains of amino acids that serve as hormones in the body, such as insulin and oxytocin. Unlike larger proteins, they act quickly by attaching to receptors on cell surfaces, triggering specific responses that control metabolism, growth, mood, and energy balance. This targeted signaling differs from steroid hormones, which enter cells and directly affect gene activity.