the pupil is the part of the eye, by which the light can break in the inside the eye. The eye steers the beam of light by making (miosis) or increasing (mydriasis) the pupil smaller with the help of the muscular portion of the iris (Adaptation).
during a pupil far-posed is always round, differs the pupil form during a miosis between the individual kinds. With some kinds (z. B. Humans, dogs) run the closing muscle of the pupil (Musculus sphincter pupillae) circular letter, thusthat also the narrowed pupil is round. With many animals this muscle runs shear-lattice-like, so that itself with narrowing crosswise oval (z. B.Horses, cattle) or perpendicular schlitzförmige (z. B. Cats, Geckos or some queues) pupil forms result in.
the different pupil forms(approximately to schlitzförmig) different animal species developed in the course of the evolution, in order to supplement the specific optical characteristics of the respective type of lens optimally. Thus schlitzförmige pupils occur only with animals with multifokalen lenses. These focus light of different wavelengths by different concentric (circular) zones thatLens. In this way a sharper picture, than with eyes with round pupils, develops whose lenses focus incident light on only one point in the center. With a multifokalen lens a round pupil would cover whole circular regions of the lens with its contraction, however forbundling certain wavelengths of the light would be necessary. On the other hand the light can always depress through any section of the concentric ring of the lens with schlitzförmigen pupils, so that an optimal bundling of the different wavelengths is ensured (J. Exp. Biol. 209, 18-25, 2005).
Israeli and US-American scientists
discovered psychological influence of the pupil size independent in the seventies that the size of the pupil is affected also by psychological processes. The reason for it is that the pupil extending Musculus dilatator pupillae over the Sympathikus indirectly also with that Limbi system in the brain is connected. The Limbi system participates also in the feeling emergence, in learning processes and in the storage of learning in the long-term memory. With special activity of the Limbi system the pupil is extended. During excessive demand the muscle and the pupil slacken becomemade smaller. Since a conscious controlling of the pupil movement is not possible, the pupil size is an indicator for the working load of humans. The procedures for the measurement of the pupil diameter are called Pupillometrie or Pupillometrik.
With the help of infrared is taken up - a camera the pupil and by computer thosePupil width determines. In this way the mental load can be measured.
pupil in the diagnostics
the investigation of the pupil belongs to each medical status of a patient. The size (largely, normally and small) is noted, the reaction to light and whether both pupilsequally large are (isokor).
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