Quick and Simple Nervous System Physiology

Hello. Let’s talk about the nervous system.

The nervous system is fundamentally broken up into two categories:

  • Central Nervous System (CNS)
  • Peripheral Nervous System (PNS)

Under the peripheral nervous system is the sympathetic and parasympathetic nervous system.

So, we’ll be briefly discussing these systems and also focus on the drugs that mainly affects how they function.

The Nervous System

As previously stated, the nervous system is composed of the central nervous system and the peripheral nervous system.

The central nervous system is composed mainly of the spinal cord and the brain. The CNS makes all the automatic responses of the body. On the other hand, the peripheral nervous system has more influence when it comes to the primary drugs that are administered to the body in terms of therapeutic response.

The sympathetic nervous system and parasympathetic nervous system act like a teeter-totter; meaning, if one is on, then the other one is off, and vice versa. So, this is what determines the drugs administered inside the hospital.

The Sympathetic Nervous System (SNS)

The sympathetic nervous system is referred to as the fight or flight response.

To easily remember this system, you can think about a bear chasing you and thinking, “Oh, snap!” That’s your sympathetic nervous system working because your body is immediately responding to the bear’s presence.

Now, whether you choose to run away from the bear or stay to fight the bear, your sympathetic nervous system is mainly working. But what are the main organs that comprise the SNS? The answer is your lungs and your heart. If you chose to run, your heart would pump faster to get more oxygen around the body and to distribute oxygen to the muscles.

The brain is also involved in the sympathetic nervous system because it decides whether to fight or run.

The Parasympathetic Nervous System

On the opposite side of the spectrum, opposite your sympathetic nervous system, is your parasympathetic nervous system. Now, whether you choose to fight or run, there are parts of your body that are least needed – like for digesting or producing urine. Therefore, the parasympathetic nervous system is your rest and digest system.

What are the parts of the body involved in the parasympathetic nervous system?

  • GI tract
  • Kidneys

You can remember this by imagining that you’re chilling out underneath a cabana. While resting, your heart doesn’t need to race, and your lungs do not require increased amounts of oxygen. If you’re just relaxing, there is no need for the brain, heart, and lungs to speed up and work hard. Therefore, when you’re resting and digesting, other organs that sustain life are activated.

For instance, the GI system can actively create feces or poop which would prompt you that your parasympathetic nervous system is doing its job.

The parasympathetic nervous system does all other activities that aren’t necessary when you’re fighting or running – digesting, creating urine and feces, even distribution of blood to the extremities. 

What to look forward to

In the next video, we will be discussing the different kinds of drugs that influence the sympathetic and parasympathetic nervous systems. We will also be tackling drugs such as:

  • Sympathomimetics and Parasympathomimetics
  • Adrenergic and antagonist
  • Anti-adrenergic receptor

We urge you to watch that video as a continuation of this lecture to gain more insight on the different drugs that affect the nervous system.

Neurological Disorder Overview: Parkinson’s, MS, MG, & ALS

Here’s a quick rundown of the four primary neurological disorders mainly Parkinson’s disease (PD), multiple sclerosis (MS), myasthenia gravis (MG), and amyotrophic lateral sclerosis (ALS). We will be touching on the signs and symptoms, pathophysiology, and client goals. After which, we will go into specific details and dissect every disease.

Right now, we will be focusing on the basic overview of MS and Parkinson’s disease.


The nervous system is basically divided into two: the central nervous system (CNS) and the peripheral nervous system (PNS). The central nervous system consists of the brain and the spinal cord while the peripheral nervous system includes the ganglia and the nerves that are mainly outside the brain and spinal cord.

                        Nervous system = CNS and PNS

  • CNS = brain and spinal cord
  • PNS = ganglia and nerves (everything outside the brain and spinal cord)

It is essential to take note that multiple sclerosis and Parkinson’s disease primarily occurs in your central nervous system while myasthenia gravis and amyotrophic lateral sclerosis affect the peripheral nervous system. ALS is just a fancy word for Lou Gehrig’s disease.

  • CNS = MS and PD
  • PNS = MG and ALS

Pathophysiology of CNS Diseases

To easily remember your central nervous system diseases, think of C-M-P. CMP stands for CNS, MS, and PD.

  • C – CNS
  • M – MS
  • P – PD

Multiple Sclerosis

When you think of MS, automatically relate it to myelin sheath because there is myelin sheath degradation in multiple sclerosis.

            MS = myelin sheath = degradation

What are myelin sheaths and how important are they in your client’s CNS?

If you remember your nursing physiology pre-requisites, a particular topic specifically in the brain is knowing what a nerve cell is and identifying its parts. The axon, or what is also known as a nerve fiber, is responsible for conduction of motor impulses. On each neuron, are attached myelin sheaths that look like a small choo-choo train.

A neuron or nerve cell would look like a palm tree if you wanted something substantial to compare it to.

Aside from protecting the nerve fibers, the myelin sheaths are also responsible for electrical impulse conduction. Moving your fingers or twitching your hands happen due to normal myelin sheaths; this is referred to as an action potential.

In MS, the myelin sheaths have degraded causing problems in the transport of impulses. Some of the notable signs and symptoms are:

  • Numbness
  • Cramping
  • Muscle weakness

Parkinson’s Disease

In Parkinson’s disease, there is a significant decrease in the amount of dopamine in your brain. You can think of it this way: There is decreased dope in the park.

            PD = decreased dopamine

What is dopamine and what’s its importance to your CNS?

Again, in your pre-requisites, it was established that dopamine in your brain helps in regulating a few key aspects in your CNS and one of those things is your blood pressure. Which is why, every time a client codes or has a hypotensive episode, dopamine is given because it is a potent vasoconstrictor. Dopamine helps in increasing the amount of blood flow to the brain, into the heart, and dilating your kidneys. But one thing that you have to take note of regarding dopamine is that it helps with your CNS and a person’s ability to move.                                                             

What are the classic signs of clients with PD?

  • Shuffling gait – moving slowly while having a shuffling walk
  • Pill rolling – due to impaired dopamine levels the motor reflexes are affected
  • Tremors in your peripherals

Part two of our lecture we will be tackling about myasthenia gravis and amyotrophic lateral sclerosis or Lou Gehrig’s disease.

See you there!