Tearing is controlled by both the autonomic nervous system and reflex actions. The parasympathetic nervous system stimulates the lacrimal glands to produce tears in response to emotional stimuli or irritation. Reflex tearing occurs due to physical or chemical irritants, such as foreign particles or fumes, which activate the sensory nerves in the cornea and conjunctiva. This sensory input is transmitted to the brainstem, triggering a reflex arc that results in tear production.
