tårbildning

Tårbildning, also known as lacrimation, is the physiological process by which tears are produced and secreted by the lacrimal glands in the eyes. This essential function serves multiple purposes, primarily lubrication, protection, and emotional expression.

Tears are composed of three distinct layers: a lipid outer layer, a middle aqueous layer, and an inner mucin layer. The lipid layer, secreted by the meibomian glands, prevents tear evaporation. The aqueous layer, produced by the lacrimal glands, is the largest component and contains water, electrolytes, proteins, and antibodies that nourish and protect the cornea. The mucin layer, secreted by goblet cells in the conjunctiva, helps the aqueous layer adhere to the eye's surface, ensuring even distribution.

There are three main types of tearing. Basal tearing is a continuous, low-level production that keeps the eyes moist and healthy. Reflex tearing is a response to irritation, such as from dust, smoke, or a foreign object, flushing out the irritant. Emotional tearing is a response to strong emotions, such as sadness, joy, or pain, and its exact physiological purpose is still debated but may involve stress reduction or social signaling.

Disruptions in tårbildning can lead to various eye conditions. Insufficient tear production, known as dry eye syndrome, can cause discomfort, blurred vision, and increased risk of infection. Excessive tearing, or epiphora, can result from overproduction or blockages in the tear drainage system.