Cns and pns relationship

The difference between centre and periphery

cns and pns relationship

from end to end connection between neurons, supported by the glial cells. The nerves the PNS into the CNS, and after processing in the CNS, instructions are . The CNS and PNS. The nervous system has two different major parts. The two parts are the central nervous system and the peripheral nervous. The central. CNS vs PNS. CNS is the Central Nervous System that functions in order to coordinate each and every activity taking place in all the parts of the.

The devil is in the details Together the spinal cord and the brain form the central nervous system CNS. It is connected to the peripheral nervous system PNS which includes the nerves in our extremities.

cns and pns relationship

But, there are big differences between the two. And, there are more cell types in the nervous system than just neurons. Without glia, growing neuronal processes rarely find their target.

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And, if they do, they will fail to form a functioning contact synapse. The glue is the true The differences in healing abilities of CNS and PNS injuries become clearer when we focus on the regional differences, which, to a large extent, depend on glial cells. In the CNS there are three main types of glial cells: But in the PNS, there are neither astrocytes nor microglia and so-called Schwann cells do the isolation.

What does that mean for an injured neuron? The basic problem An injury to nervous tissue always leads to the same basic problem. A given signal originating from the cell body can't reach its destination any more: If the process of a neuron is severed, the part without the cell body will degrade. If the process of a neuron is not severed but loses its insolation because oligodendrocytes in the CNS or Schwann cells in the PNS are damaged and die then the signal will stop and attempts to regenerate the isolation sheet will start.

The situation in the PNS Sending out new processes and re-establishing the right contacts works relatively well in the PNS, for example after a deep cut into or through a finger.

This is because regenerating neurons receive considerable support. Scavenger cells from the immune system hurry to remove the debris of the old isolation material, while they excrete molecules, which encourage Schwann cells to participate.

The latter rejuvenate to a state without isolation abilities, but are capable of secreting so-called growth factors.

Difference Between CNS and PNS | Difference Between | CNS vs PNS

These have the same effect on a newly built neuronal processes as fertilizer to a plant. Now the regenerating neuron is building new processes, extending along the old path towards their old contact sites and able to re-establish these contacts. After that, the scavenger cells change back into the resting state, stopping further growth.

The Schwann cells will build a new isolation sheet on the processes that were not cut, but that lost their isolation sheet, but will also do so on the newly formed processes.

The difference between centre and periphery

This mechanism, called remyelination is, in the PNS, efficient and quick. And in the end sensitivity as well as motor functions will be re-established. In the CNS immune and glial cells will react, but their signals are not supportive. These nerve roots are named according to the spinal vertebrata which they are adjacent to. In the cervical region, the spinal nerve roots come out above the corresponding vertebrae i.

cns and pns relationship

From the thoracic region to the coccygeal region, the spinal nerve roots come out below the corresponding vertebrae. It is important to note that this method creates a problem when naming the spinal nerve root between C7 and T1 so it is called spinal nerve root C8.


In the lumbar and sacral region, the spinal nerve roots travel within the dural sac and they travel below the level of L2 as the cauda equina. Cervical spinal nerves C1—C4 [ edit ] Further information: Cervical plexus The first 4 cervical spinal nerves, C1 through C4, split and recombine to produce a variety of nerves that serve the neck and back of head. Spinal nerve C1 is called the suboccipital nervewhich provides motor innervation to muscles at the base of the skull.

cns and pns relationship

C2 and C3 form many of the nerves of the neck, providing both sensory and motor control. These include the greater occipital nervewhich provides sensation to the back of the head, the lesser occipital nervewhich provides sensation to the area behind the earsthe greater auricular nerve and the lesser auricular nerve.

The phrenic nerve is a nerve essential for our survival which arises from nerve roots C3, C4 and C5. It supplies the thoracic diaphragmenabling breathing. If the spinal cord is transected above C3, then spontaneous breathing is not possible.

cns and pns relationship

Brachial plexus C5—T1 [ edit ] Further information: Brachial plexus The last four cervical spinal nerves, C5 through C8, and the first thoracic spinal nerve, T1, combine to form the brachial plexusor plexus brachialisa tangled array of nerves, splitting, combining and recombining, to form the nerves that subserve the upper-limb and upper back.

Although the brachial plexus may appear tangled, it is highly organized and predictable, with little variation between people. See brachial plexus injuries.