The nervous system can be considered our bodies control hub. It’s responsible for deciphering sensory input, controlling motor function (movement), and unification and storage of both incoming and outgoing data.
Two Primary Components of the Nervous System
The nervous system can be broken down into two primary components which while serving dedicated roles are tightly integrated and would not be of any use without one another.
These two components are:
- Central nervous system
- Peripheral nervous system
Central Nervous System
The largest part of the nervous system is appropriately named the central nervous system. And it includes both the brain and the spinal cord.
This is where we consider the more complex processing to occur, including:
- Formation of thoughts and ideas
- Control of muscle movements
- Storage and retrieval of information
Quite literally, our central nervous system is what makes us human and what drives our everyday thoughts. In a sense, it is who we are and the main operating unit of our journey through this world.
Whose in control
While we often think our conscious thoughts control the majority of our muscle movements, research has shown that muscle movements can begin before our conscious thoughts are even activated.
Peripheral Nervous System
The peripheral nervous system is responsible for communicating external events and inputs to the central nervous system. It can be thought of as the outward facing unit of the central nervous system; our link to the outside world.
Without input from the peripheral nervous system, we would not be able to interact with the outside world and in cases of extreme sensory deprivation, hallucinations follow.
At the most fundamental level, the nervous system is made up of individual brain cells which work together to synchronize the diverse information exchange that constantly takes place throughout it. But not all brain cells are the same and different sub-types exist.
The two primary sub-types are:
- Glial Cells
The most abundant brain cell is the neuron. This is how the central nervous system communicates and functions. It is estimated that the average adult has roughly 86 billion neurons .
These neurons operate in a fashion similar to a switchboard and electric potential (also referred to as action potential) is passed along neuron from the dendrites (which accept the incoming signals) to the axon terminals (which output the outgoing signals).
As this electric potential passes through a neuron chain, decisions are made at each intersection whether or not the signal should continue. And this process continues to progress until no more active paths remain in the chain.
Glial cells are the second type of brain cell and they play a supporting role to the neuron. They work to support the development of new neurons and help line the axon (connective terminal) of neurons to form enforcing myelin sheaths (which improves the transmission of signals at frequently used pathways).
Improving Transmission Along Neural Pathways
If we think of the axon component of a neuron cell as the center of a cable, the myelin sheaths are the protective insulating outer wrapper of the cable. Its purpose is to improve the efficiency of the signal passed along the axon and reduce external interference.
There are four primary types of glial cells found in the central nervous system:
- Ependymal cells
Two other types of glial cells can be found in the peripheral nervous system:
- Satellite cells
- Schwann cells
They serve similar roles to astrocytes and oligodendrocytes (respectively) but have some minor differences in their composition.
Essentially, all glial cells improve the functioning of the neurons and improve the most active pathways of the nervous system.
This section provided a brief introduction to the nervous system and its basic components. Understanding the basics should allow you to make better sense of the remainder of the sections in this chapter.
Key takeaways include:
- The nervous system is our bodies control hub and is made up of two distinct components; the central and peripheral nervous systems
- The brain and spinal cord make up the central nervous system and these control our thoughts, muscle movements, and information processing
- The peripheral nervous system senses and communicates external events to the central nervous system
- Cells that make up the nervous system are called brain cells and primary two sub-types exists
- Neurons are the most abundant type of brain cells and facilitate the majority of the nervous system’s communication
- Glial cells are the other type of brain cells and play a supporting role to neurons, guiding their development and improving their efficiency