The pupil is the black circle found in the middle of the iris.
The pupil is the black circle that, located in the middle of the iris , allows light to enter. This opening, which can contract or dilate according to needs, is responsible for regulating the level of light that accesses the retina .
The usual thing is for the pupil to be between three and nine millimeters in diameter , depending on the person and the situation. When the subject is in a dark environment, the pupil widens in an attempt to absorb more light.
These changes in size are possible thanks to two muscles that, innervated depending on the case by sympathetic or parasympathetic nerves , drive the opening or closing of the pupil.
Pupil contraction and dilation
The contraction of the pupil, which is called miosis , is an organic response to increased luminosity . This reduction in pupil size, however, can be caused by other factors, such as an illness or the consumption of certain drugs. The parasympathetic nervous system is responsible for regulating miosis.
The opposite of miosis is mydriasis , which is the dilation of the pupil. Regulated by the sympathetic nervous system, this response involves a reaction to darkness .
The pupils constrict or dilate depending on the lighting conditions.
anisocoria
Anisocoria is a disorder characterized by inequality in the size of the pupils. In milder cases, the difference is around 0.5 mm, although it can reach a millimeter, and this occurs in 1 in 5 people without other prominent health problems.
It is worth mentioning that anisocoria can be genetic (if a baby is born with this characteristic and it can also be seen in a family member). On the other hand, this phenomenon can take place temporarily; As long as it doesn't last long, it is not a worrying problem. When anisocoria lasts indefinitely and exceeds a millimeter, then it is necessary to perform tests to rule out ocular, vascular, neurological or brain diseases.
The beauty of the pupils
Although the iris is the most characteristic part of the eye, since it gives it its color and texture, it is common to use the term pupil to refer to it, a confusion that can be seen in many areas, except for medicine. In this sense, the pupil is considered one of the determining aspects of physical attraction . In many cultures, it is common for light eyes (blue, light blue or green, among other possible colors and combinations) to be considered a symbol of beauty over dark eyes (brown or black, although, according to opinion and despite the lack of accuracy, honey-colored eyes can fall into this category).
Since the color and texture of the eyes make this part of our body a fundamental feature, poetry and music talk about them very often. Since time immemorial, there has been a large number of verses dedicated to the pupils, exalting their beauty in every possible way, comparing them to windows through which we can see the universe itself, the sea or the sky, or to mirrors that allow us see ourselves, among many other possibilities.
The concept linked to education
Pupila, on the other hand, is the feminine version of pupilo . This term refers to students who receive some food at the educational center or who directly live there and see their families on weekends or every certain amount of time, either due to the institute's rules or for personal reasons, such as difficulty traveling home frequently.
«In my childhood I was a pupil of a nuns' school» y "The students of the San Bautista School have publicly complained about the treatment their teachers receive" son expresiones que reflejan este uso.