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.