BIOL 2410 Lecture Notes - Lecture 23: Ciliary Muscle, Parasympathetic Nervous System, Sympathetic Nervous System
2 Dec 2016
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Document Summary
Changes in the size of the pupil determine how much light reaches photoreceptors of the eye. Pupils dilate in response to low light conditions. Controlled by the sympathetic nervous system (superior cervical ganglion) -> radial muscle contracts. Pupils constrict in response to high light conditions. Controlled by the parasympathetic nervous system (cranial nerve iii) -> circular pupillary muscles contract. The shade of the lens is then used to focus the light ** Consensual light re ex: light that reaches the retina results in a single in the optic nerve -> thalamus -> mid-brain -> pupil constriction. The pupil also controls the depth of the eld. A shallow eld depth only allows material at the forefront to be visible. A full depth of eld allows the full depth of the image to be seen. Narrows the light that is entering the eye. Changes the focus of light on the photoreceptors.
