We leak when we cry because our eyes produce more tears than our tear drainage system can handle, leading to overflow.
When you cry, your lacrimal glands (tear glands) go into overdrive, producing tears for various reasons, whether it's emotional distress, physical irritation, or simply to keep the eye lubricated. Here's a breakdown of why those tears sometimes escape:
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Tear Production Exceeds Drainage: Under normal circumstances, tears are produced constantly to keep the eye moist and wash away debris. When you blink, the eyelid spreads these tears evenly across the eye's surface. Excess tears then drain through small openings called puncta, located in the inner corners of your eyelids, into the lacrimal sac and then down the nasolacrimal duct, which connects to the nasal cavity. However, when you're crying intensely, the tear glands produce tears faster than this drainage system can process, leading to overflow and tears streaming down your face.
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The Role of Tears: Tears aren't just water. They consist of three layers:
- Oily Layer: This outer layer prevents the tears from evaporating too quickly, ensuring the eye stays lubricated. Without this oily layer, our eyes would quickly become dry and irritated.
- Watery Layer: This middle layer is the thickest and contains water, salt, and proteins, providing moisture and washing away irritants.
- Mucus Layer: This inner layer helps the tears spread evenly across the surface of the eye and adhere properly.
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The Nasolacrimal Duct's Capacity: The nasolacrimal duct, while efficient, has a limited capacity. Think of it like a drainpipe; it can only handle so much liquid at once. When the flow of tears is too rapid, the duct becomes overwhelmed, and the excess spills out onto your cheeks.
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Why Crying Makes Your Nose Run: Because the nasolacrimal duct connects to your nasal cavity, some of the tears drain into your nose. This is why you often experience a runny nose when you cry; those excess tears are essentially draining into your nasal passages.
In summary, we "leak" when we cry because the tear production during crying overwhelms the tear drainage system of our eyes.
