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Ganglion cells are the cells comprising masses of nerve tissues in the body. These masses are known as ganglia. The cells themselves consist of axon and dendrite structures that send and receive nerve impulses. The two most common types of ganglion cells are found within the adrenal glands and within the eye’s retina, although cells can also be found in other parts of the nervous system. These cells help transmit information throughout the body.
The adrenal gland’s cells are found specifically in the adrenal medulla, a portion of the gland that distributes the hormones norepinephrine and epinephrine into the bloodstream. These hormones direct the body when it is active or under stress, increasing heart rate, raising blood pressure, and so forth. Ganglion cells aid in these hormones’ release, so they play an important role in the body’s system of "fight or flight."
A retinal ganglion cell comprises the other main category of ganglion cells. These cells serve as the mediator between the eye and the brain. Retinal cells collect information from the eye’s rods and cones and transmit this information to different regions of the brain via optical nerves. Various types of retinal cells address differing kinds of information, such as the amount of color and contrast in images. Types include midget cells, parasol cells, bistratified cells, and photosensitive cells.
Ganglion cells are also distributed throughout the parasympathetic and sympathetic nervous systems, areas that control the body in rest and in activity, respectively. Most parasympathetic cells, such as the adrenal cells, are located near organs, while sympathetic cells rest around the spinal cord. The parasympathetic cells function much the same as other ganglion cells in transmitting information throughout the body. In addition, the spinal ganglia relay information gained from the senses to the brain through sensory neurons. Clusters of ganglia called a plexus often work together to perform functions.
Although ganglion cells are usually found in the peripheral nervous system outside the brain and spinal cord, some of these neurons are located inside the brain. Basal cells share connections with the brainstem, the thalamus and the cerebral cortex. As such, the cells play an important part in nearly every brain function from learning to body movement.
Ganglion cells populate the human body by the millions. These tiny neurons have been the source of numerous Nobel Prize studies. In the body, they are the conductors and the cornerstones of the nervous system.
@KoiwiGal - It's interesting because originally they assumed that that part of the eye's anatomy would be the most sensitive, because it's where all the ganglion cells converge as the optic nerve.
It wasn't until they "discovered" the blind spot and realized how it corresponded to the anatomy of the eye that they figured it out.
Squids and things like that don't have that blind spot either, because they evolved eyes separately from invertebrates.
I think that's really interesting, that it was possible not to have this weak spot, but that the flaw just kept getting passed down.
I read once that the retinal ganglion cells are unique because they are basically a part of the brain that is practically exposed.
Ganglion cells of the eye are attached to the optic nerve which is what creates the "blind spot" in your eye.
If you want a demonstration of the blind spot there are lots of ways to see it online, but essentially it's a point where no information comes into your eye, and where the brain compensates by guessing at what is there so you don't notice it.
The ganglion cells are there to help process the visual information you're receiving, so it's kind of ironic that in that one part of the eye they actually block information from being received.
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