The iris is not innervated directly, however the iris sphincter muscle is affected by the sympathetic and parasympathetic nervous systems. Sympathetic stimulation causes pupil dilation while parasympathetic nervous system causes pupil constriction. The parasympathetic response is quicker because of the proximity of a parasympathetic ganglion (ciliary ganglion) to the eye. The sympathetic response is slower because all sympathetic ganglia are confined to the spinal cord. This is the reason why people adjust faster to a bright shining light than darkness.
The iris controls how much light enters the pupil by adjusting its size. In bright conditions, the iris contracts to make the pupil smaller, reducing the amount of light that enters the eye. In dim conditions, the iris relaxes to dilate the pupil and allow more light in for better visibility.
The colored portion that regulates the amount of light in eye is called as iris. The hole through which light passes inside the posterior chamber is called as is called as pupil. The color of the iris changes as per color of the skin pigment. It has got circular muscles and radial muscles in it. In fight or flight responce, it is dilated through sympathetic nerve stimulation. In relaxed and stress free envirinment pupil is constricted via parasympathetic nerve stimulation.
The Iris contains the muscles that control Pupil size.
The iris, which is the colored part of the eye, regulates the amount of light that goes into the eye by controlling the size of the pupil. The muscles in the iris can expand or contract the pupil in response to changes in light intensity.
The colored part of the human eye that controls how much light that passes through the pupil is called the iris.
The color portion of the eye is the iris. This part of the eye gives it its color and controls the size of the pupil to regulate the amount of light that enters. The iris contains muscles that adjust the pupil size in response to lighting conditions.
The colored part of the eye is called the iris. The black dot in the middle is the pupil which is covered by the lens.
The visible colored part of the eye that controls pupil dilation is the iris. The iris regulates the size of the pupil in response to light conditions and helps to control the amount of light that enters the eye.
The amount of light is actually controlled by the iris sphincter muscle, or the iris. It is controlled by parasympathetic fibers that originate from the Edinger-Westphal nucleus, travel along the oculomotor nerve (CN III), synapse in the ciliary ganglion, and then enter the eye via the short ciliary nerves.
The opening in the center of the iris is called the pupil. It is responsible for controlling the amount of light that enters the eye by dilating or constricting in response to different lighting conditions. This helps to regulate the amount of light that reaches the retina at the back of the eye for optimal vision.
The colored part of the eye is called the iris. The colored part of the eye is called the iris.