Biology and Behavior

Critical Thinking

Biology and Behavior

The Nervous System

Abstract

The human body has been a mystery to man ever since he has been able to think and feel which goes back quite a ways. With all of our thousands of years of research discovering what works and what doesn’t, what does this part do and how does it do it and what happens if I do this to that. There are still many areas of the human body and mind that we do not fully understand. The body and the brain with all of its own mysteries have a magnificent way of protecting and healing themselves that is in a sense both beautiful and amazing. Nature has provided for humankind since first put on this planet and the human body is a part of that nature like every other living thing on the planet. It interacts with nature and the environment and it reacts to it as well. Our bodies know when something is good for us and when something is wrong by sending signals, it knows when something is physically or mentally a threat to its survival and can take proactive measures before we are even aware and completely without our knowledge. One area where our body does this is in pain management. Perhaps this goes all the way back to when we were living in caves and had to fight off giant creatures to eat and survive, we couldn’t be stopped or distracted by something as trivial as pain. So we dealt with it later. Today we still possess the same ability, the life or death situations may have changed slightly but the mechanisms are all there still functioning as they did back in those cave dwelling days I’m sure. There are many situations where our bodies suppress pain and enabled us to continue on, soldiers in combat situations experience this frequently as do others in similar situations. You do not however need to be in a life or death situation, pain is pain and injury is injury whatever the cause. Athletes are a major recipient of this benefit in similar stressful situations. There have been documented cases where athletes have sustained injury and continued on unaware of their condition. This exercise explores this phenomenon, its causes and the effect it has on us physically and mentally.

Introduction

It was back around 1988 that I first witnessed what is known as “runners high”. I was on my way to work one morning when up ahead I saw a person jogging along side the road. As I approached he suddenly and without warning turned from the sidewalk and ran directly in the path of my car. I brought the car to an abrupt stop and he disappeared in front of me. As I strained to see beyond the hood, he popped up with the look of a deer caught in the headlights. He seemed to be shocked and disoriented, like he had no idea how he ended up in the middle of a two lane street in front of a car. I yelled to him and asked if he was alright but he just stood there and then trotted off. I could only attribute this bizarre episode to what some people refer to as “runners high”. I had heard of it but didn’t know what it was.


I can not imagine what this runner was thinking or feeling but it seemed to me that he was in some sort of dream state or euphoria. It is believed that many runners can experience a state of euphoria while running. Most runners describe it as simply a pleasant feeling after running a certain distance when the body and mind are both highly stimulated and senses seem to be elevated. Others say when the stimuli around you are near perfect and you are feeling good you are actually feeling a type of “high”. Although there is no official definition as to what runners high actually is or if it even exists, there are physical and psychological details that demonstrate something is going on. Most obvious are the biological and psychological aspects associated with it. When put under stress the mind reacts with endorphins which are commonly associated with runners high.

Endorphins

In nineteen seventy-five, John Hughes and Hans W. Kosterlitz of the University of Aberdeen managed to isolate peptides found occurring naturally within the brain. These peptides were called endorphins, meaning morphine from within, and were found to have pain reducing effects.


These neurotransmitters are chemically similar to and act much like the opiate drugs opium and morphine and the brain has receptors that respond to morphine which suggest that the human body produces its own morphine like substances which we now call endorphines and enkephalins. When stress is detected by the brain, it sends out signals, or opiates, which bind at the receptor sites, and the pain is alleviated. Feelings of euphoria follow and soon become apparent.


Studies on athletes have shown that endorphine levels increase with exercise. This could explain the mood changes, euphoria and increased resistance to pain that occur during running for an extended period.

Pain

How do you know to pull your hand away from a flame or withdraw your mouth from a cup of hot coffee? Something called Nociceptive or somaticpain response, this is a natural response to noxious stimuli and something every human being needs to sustain life. Some are born with congenital insensitivity to pain and tragically most die at an early age. If you break an ankle, the pain keeps you from walking around on it, so the bone can heal. Nociceptors are sensory receptors, or nerve endings, that react to mechanical, thermal, and chemical stimuli that may damage tissues. They relay nerve impulses — electrical messages from the site of injury in peripheral tissues such as skin, muscles, and joints — to the dorsal horn, an area in the spinal cord that acts as a switchboard. There, different chemicals determine whether these electrical messages reach your brain, where you actually perceive pain.

Pain Gates

Pain is the body’s way of telling you something is wrong and needs attention.


There are different types of pain signals (slow or fast), which travel along different pathways in the brain. These signals can be affected by endorphins in the brain and the brain can send signals down the spinal cord to open and close the nerve gates.


In times of anxiety or stress, descending messages from the brain may actually amplify the pain signal at the nerve gate as it moves up the spinal cord. Alternatively, impulses from the brain can “close” the nerve gate, preventing the pain signal from reaching the brain and being experienced as pain. These can be roughly divided into sensory (physical being and activities), cognitive (thoughts), or emotional (feelings) areas, although of course there is substantial overlap between these areas in practice.

The Nervous System

Your nervous system is like a built-in computer, it keeps all of your systems working together and working smoothly. In fact, all of the thinking that you do is done by your nervous system. It also handles memory chores and keeps your thoughts organized. Your nervous system provides you with dreams, too, and it regulates your muscles. It tells them when to run, and when to speed up or slow down. Your nervous system regulates things you don't usually even think about, like breathing and blinking your eyes. Neurons carry information through the nervous system in the form of brief electrical impulses called action potentials. When an impulse reaches the end of an axon, neurotransmitters are released at junctions called synapses. The neurotransmitters are chemicals that bind to receptors on the receiving neurons, triggering the continuation of the impulse.


All living organisms interact with their environments; organisms receive multiple signals from the environment via their sensory systems and respond by way of their somatomotor system. Both sensory processing and motor actions are entirely under the control of the central nervous system.


The brain, along with the spinal cord and network of nerves, controls information flow throughout the body. The brain stem connects the brain with the spinal cord. Every message transmitted between the brain and spinal cord passes through the medulla oblongata—a part of the brain stem—via nerve fibers. The medulla regulates the heartbeat, breathing rate, and blood-vessel diameters as well as other functions such as hiccups.


Another brain stem component, the pons (meaning "bridge"), conducts messages between the spinal cord and the rest of the brain, and between the different parts of the brain. The midbrain conveys impulses between the cerebral cortex, pons, and spinal cord, and also contains visual and audio reflex centers involving the movement of the eyeballs and head.


Jeffrey Lackner, director of the Behavioral Medicine Clinic, meets with Sherry Julian to discuss ways she can cope with the stress that's causing her pain.

Dealing with Pain

The checks and balances system of endorphins physically consists of chains of amino acids, which make up the chemical messengers known as neuropeptides. The transmission of pain and feelings of pleasure exist within the brain due to nerve impulses. These impulses are relayed via neurotransmitter chemicals thus causing the release of neuromodulator chemicals, such as endorphins. These messengers differ from neurotransmitters in the fact that they modulate feelings of pain and pleasure, rather than convey the actual feelings. In order to change the feelings of pleasure and blockage of pain, the endorphins must reduce activity in the thalamus and cerebral cortex. This occurs by the neuromodulator affecting the dopamine pathway by binding to a specific opiate receptor site. Endorphins “shut off” the nerves in the frontal lobe, inhibiting feelings of pain, and allow this area to flood with dopamine, hence the feelings of euphoria.

Conclusion

There are many athletes who can attest to the healthy and healing powers of exercise and the feeling they sometimes get during a long run or a very physical activity such as a football game or rugby match. Endorphins physically and mentally aid athletes and help them push past mental barriers which they may thought were unobtainable. The competitive nature of athletes drives them to continually push themselves further either individually or as a team. In a team sport the psychological effect may even be stronger due to the fact that the athlete knows that others are dependent on him or her to perform. This is especially true in a sport such as rowing or a relay race where one athlete must work in concert with others as a cohesive unit. There is something about the fact that every player is depending on the other to keep going which aids the endorphins in each system to push past the body's point of termination. The rush of endorphins will keep circulating to create more and induce a heightened activity which the athlete can sustain for longer periods. There are incidents which have been documented where athletes such as marathon runners and football players have sustained injury that should have ended their activity but never realizing the injury until the competition had ended and they returned to a relaxed state. Our bodies are smarter than we think and there are also enzymes whose sole purpose is to degrade the modulating neuropeptides once the endorphin has served its purpose. It is so far impossible to adequately produce a synthetic version of the body's natural pain fighter. Many have tried but so far with no satisfactory results.

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