Photoreceptors
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- Category: Science
- Date Submitted: 08/14/2011 08:20 PM
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Photoreceptors
Abstract
We will discuss in this essay the workings of the Photoreceptors and how they determine vision, the perception of light. Also we will briefly discuss how photoreceptors work in other animals and how they work, if at all, in humans without sight.
Photoreceptors 1
The peripheral nervous system is described as all parts of the nervous system
except the brain and spinal cord, which is considered the part of the central nervous
system. The peripheral nervous system, or the PNS, connects the central nervous
system (CNS) to the remainder of the body, and is the conduit through which neural
signals are transmitted to and from the CNS. (Gale Encyclopedia of Neurological
Disorders, Hoyle and Arthur, 2005).
These neurons are broken down into three categories, sensory, motor and
associated neurons. Motor neurons control the muscles and glands, the sensory neurons
are associated with the eyes, ears and skin, while the associated neurons connect the two.
(The Living World, Johnson and Lobos, 2010) We will concentrate on a particular part of
the PNS, the sensory receptors, and in this case, the photoreceptors. Photoreceptors
respond to light, which is what vision is, the perception of light. Eyes contain sensory
receptors called rods and cones that respond to photons of light. The light energy is
absorbed by the pigments in the rods and cones, which respond by triggering nerve
impulses in sensory neurons, sending it to the CNS, particularly the brain.
After sending these signals from the photoreceptors through the retina (the
eyeballs, the locations of the rods and cones) to the cerebral cortex, the brain interprets
this information and provides the images of what we are seeing....
Abstract
We will discuss in this essay the workings of the Photoreceptors and how they determine vision, the perception of light. Also we will briefly discuss how photoreceptors work in other animals and how they work, if at all, in humans without sight.
Photoreceptors 1
The peripheral nervous system is described as all parts of the nervous system
except the brain and spinal cord, which is considered the part of the central nervous
system. The peripheral nervous system, or the PNS, connects the central nervous
system (CNS) to the remainder of the body, and is the conduit through which neural
signals are transmitted to and from the CNS. (Gale Encyclopedia of Neurological
Disorders, Hoyle and Arthur, 2005).
These neurons are broken down into three categories, sensory, motor and
associated neurons. Motor neurons control the muscles and glands, the sensory neurons
are associated with the eyes, ears and skin, while the associated neurons connect the two.
(The Living World, Johnson and Lobos, 2010) We will concentrate on a particular part of
the PNS, the sensory receptors, and in this case, the photoreceptors. Photoreceptors
respond to light, which is what vision is, the perception of light. Eyes contain sensory
receptors called rods and cones that respond to photons of light. The light energy is
absorbed by the pigments in the rods and cones, which respond by triggering nerve
impulses in sensory neurons, sending it to the CNS, particularly the brain.
After sending these signals from the photoreceptors through the retina (the
eyeballs, the locations of the rods and cones) to the cerebral cortex, the brain interprets
this information and provides the images of what we are seeing....