Introduction to the central and peripheral nervous systems

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The smell of a morning coffee, the memory of last christmas, and the pain of touching a hot surface. That’s your nervous system at work!

The nervous system allows each body system to communicate with each other, and monitors internal and external changes to build a proper response that keeps us alive and kicking!

Now, to make things a bit easier, the nervous system is structurally subdivided into two anatomical components, called the central nervous system, or CNS or short, which consists of the brain and the spinal cord and the peripheral nervous system, or PNS, which consists of the remainder of the nervous system outside of the CNS.

Both the CNS and the PNS are made up of the functional units of the nervous system, called neurons or nerve cells.

These cells have many parts, with the main part being the cell body, which houses the nucleus of the cell.

From the cell body arise two types of extensions: dendrites, which are short projections and may be numerous, and an axon, or nerve fiber, which is a single long extension that looks like a thread.

Now, neurons are special because they’re able to receive and send electrical impulses that allow for communication with other neurons, as well with effector cells, like muscle cells.

This process starts at the dendrites, which receive electrical signals from other neurons and convey it towards the cell body. Then, the cell body produces an electrical impulse and sends it through its own single axon.

Many axons are covered with a layer of lipids and proteins that speed up the conduction of these impulses, called the myelin sheath.

Now, the electrical impulse eventually reaches the distal parts of an axon, called the axon terminals.

Here, an axon terminal can meet up with a dendrite of another neuron, and this contact site is called a synapse which facilitates the communication between neurons.

Now, there are a few types of neurons that are structurally different from one another. Neurons that have two or more dendrites and a single axon, like the one we just described, are called multipolar neurons.


The central nervous system (CNS) is the part of the nervous system that consists of the brain and spinal cord. The CNS controls all voluntary muscle movement and sensations in the body. The peripheral nervous system (PNS) is the part of the nervous system that transmits signals from the central nervous system to the rest of the body, and vice versa.

The PNS consists of two parts: the somatic nervous system and the autonomic nervous system. The somatic nervous system controls voluntary movements, such as walking or talking. The autonomic nervous system controls involuntary movements, such as breathing and bowel movements.


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