räpyttäminen

Räpyttäminen, also known as blinking, is a physiological reflex where the eyelids close and then immediately reopen. This involuntary action is crucial for maintaining eye health and visual clarity. The primary function of blinking is to moisten the surface of the eye, the cornea, by spreading a thin layer of tears produced by the lacrimal glands. This tear film lubricates the eye, preventing dryness and irritation, and also washes away small particles of dust and debris that may land on the ocular surface.

The act of blinking also serves to protect the eye from potential harm. A rapid blink, often triggered by a sudden stimulus such as a puff of air or a bright light, acts as a protective mechanism, preventing foreign objects or damaging agents from reaching the delicate eye tissues. Furthermore, blinking clears away dead cells and mucus from the eye's surface.

The frequency of blinking can vary depending on several factors. In humans, the average blinking rate is around 15 to 20 times per minute, though this can decrease during activities requiring intense visual focus, such as reading or using a computer, and increase during conversation or when feeling anxious. Environmental conditions, like dry air or wind, can also affect blinking frequency. Conscious control over blinking is possible, but the reflex is largely involuntary and regulated by the brainstem.