When looking at the nervous system it helps to think about it like as an information highway and to view it like the electrical wiring in your house
In previous lessons we have looked at the brain and the hormone system. This lesson we are going to look at the nervous system, aka the wires of your bodies' house, and how it sends signals from your body (arms, legs, hands, feet etc...) and connects them to the spine and the brain.
- Humans have a group of neurons, called mirror neurons, that are responsible for some behaviors being contagious, such as yawning.
- You have involuntary reflexes that are not controlled by your brain.
- The fastest signal transmission in the body is transmited at a signal at 268 miles per hour. The slowest signal transmission is within the skin at 1 mile per hour.
- We lose neurons as we age, starting at around 20 years old in humans. 1/10 of our neurons are gone by the time we turn 75.
- The optic nerve crosses over in the brain. This means that the right optic nerve crosses to the left side of the brain and vice versa. This allows an image to be produced by the brain.
- The longest nerve in the body is the sciatic nerve. It runs from the spinal cord to the toes on each side of the body.
- The bowel is controlled by a separate part of the autonomic nervous system known as the enteric nervous system. It regulates digestion and bowel movements.
- The spinal cord has roughly 13.5 million neurons throughout its length.
- The body has billions of nerve cells.
- Your nervous system is hackable as scientists are now developing ways to “hack” into the immune system, gaining the ability to control brain cells with the flash of a light. You can aslo control it with things like breathing
For example, we have the sciatic nerve that originates at the base of the spine and runs along the back of each leg into the foot. The scaitic nerve is motor (helps you cordinate muscular movement that helps you walk) and sensory (provides feeling to the foot and the majority of the lower leg).
To understand how your sciatic nerve signals to your brain we have to look at what is called the somatic nervous system (the part of the nervous system that is under your control like moving your foot or feeling the ground under your feet). The move the foot signal travels from the foot through the sciatic nerve where it reaches the spine (the spine has 3 main highways that carry information up the brain).
There is so much we could unpack here (what determines if the signal gets sent, what determines if the signal gets relayed from the spine to the brain, what paths does the signal follow up, how the brain decides to cordinate the movement with cerebellum, the path back down and finally the foot moves), but let's leave it at 10,000 thousand ft.
Nerve fiber types
- A- Thickest and fastest conducting, motor and skin signals use this wire. They can be further subdivided into alpha (α) Aα; beta (β) Aβ; , gamma (γ) Aγ, and delta (δ) Aδ. These subdivisions can actually be subdivided as well, but let's not go too far down the rabbit hole lol
- B- Medium sized, these play a role in your autnomic nervous system (the system that is happening outside of your control)
- C The smallest and slowest type, these also play a role in your autnomic nervous system (the system that is happening outside of your control)
What does this have to do with you and your pain?
The old ideas is that if you are walking in the street and you twist your ankle, and the tissue damage uses the A-delta/C fibers to send an immediate pain signal to your brain so the brain can tell you to stop using the ankle, walk with a limp to not damage it more by using other not damaged tissue, seek medical help and cancell weekend hiking plans so you do not cause more damage.
Why the old idea is flawed... What happens when you add context that you twisted your ankle in the street with a bus coming, if these wires always sent pain it would be dangerous becuase you would not be able to block out the pain long enough to cross the strees to get to safety. We have seen this in our life or heard of stories like this where once the person feels safe then the brain decides that it can now take care of the twisted ankle. This is also how people can be shot in battle and still perform heroic acts and not need treatment till the people they are protecting are safe.
Remember we have nociceptive fibers, but not pain fibers. Have you ever wondered why someone with an old injury gets pain during temeprature changes?
- Tissue Inflammation
- Nerve Inflammation
- Immune system
This process can be a lot, so do not hesitate to slow down to your own pace. You are not alone. If you are stuck and need more help do not even hesitate to reach out to us.
Your life is waiting for you again on the other side of this course, till next time guys 🙂