In biology, an automatic and inborn response to a stimulus that involves a nerve impulse passing from a sensory nerve cell to a muscle or gland without reaching the level of consciousness.
Simple reflexes include sucking, swallowing, blinking, scratching, and the knee jerk. Most reflexes consist of complex patterns of many unconsciously coordinated muscular actions that form the basis of much instinctive behavior in animals. Examples include walking, standing, the cat's righting reflex, and basic sexual acts.